Construction Glossary for Los Angeles Residential Projects

224 terms covering project delivery, contracts, cost structure, foundations, structural systems, grading, waterproofing, seismic retrofit, fire rebuild, insurance, permitting, and the construction processes that shape complex residential projects across Los Angeles.

Construction has its own language. The terms below cover project delivery methods, contract structures, cost and budget mechanics, foundation engineering, structural systems, earthwork and grading, waterproofing, roofing, mechanical and electrical systems, seismic design, fire rebuild requirements, insurance, permitting, environmental compliance, and the building processes that shape complex residential projects across Los Angeles. Each definition draws from the same project experience that informs our 35+ technical guides, and where a topic is covered in greater depth on a dedicated page, we link to it directly.

Last updated: April 2026  |  224 terms

About This Page
This glossary is written by Jeff Benson, Principal of Benson Construction Group, based on 24 years of construction experience including over $300 million in completed residential projects throughout Beverly Hills, Bel Air, Pacific Palisades, Malibu, and the greater Los Angeles Westside. Definitions reflect how these terms apply in practice on complex residential projects, not textbook abstractions.
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Project Delivery & Contract Terms

Construction Manager at Risk (CMAR)
A project delivery method where the construction manager joins during the design phase, provides pre-construction services including cost estimating, constructability review, and scheduling, and then commits to delivering the project within a Guaranteed Maximum Price. The "at risk" designation means the CM carries contractual financial responsibility: if actual costs exceed the GMP for work within the defined scope, the CM absorbs the overage from their fee, margin, and contingency. CMAR is standard in commercial construction but rare in residential, where most projects still use lump-sum or cost-plus contracts. It is increasingly relevant for complex residential projects in Los Angeles, including hillside construction, fire rebuilds, and projects with significant geotechnical or regulatory complexity.
Full guide: What Is CMAR? →
Guaranteed Maximum Price (GMP)
A contractual price ceiling representing the most the owner will pay for the defined scope of work. The GMP includes trade costs, general conditions, the CM's fee, and contingency allowances. It is developed through months of progressive budget refinement: parametric modeling at feasibility, assembly-based estimating at schematic design, quantity takeoffs with preliminary subcontractor pricing at design development, and competitive subcontractor bidding at construction documents. If actual costs come in below the GMP, savings are shared between owner and CM, typically at a 75/25 split. If costs exceed the GMP for work within the defined scope, the CM absorbs the difference.
Full guide: Budget Development & Cost Control →
Open-Book Accounting
A cost transparency structure where every project cost is visible to the owner at the actual amount paid. The owner sees every subcontractor bid, every subcontract, every invoice, every material purchase, and every general conditions charge. Nothing is marked up and resold. The CM's compensation is the fee, a defined line item in the GMP, not a hidden margin applied to pass-through costs. This is fundamentally different from cost-plus contracts where the GC applies a 10-15% markup to pass-through costs, and from lump-sum contracts where the owner has no cost visibility at all.
Full guide: What Is CMAR? →
Design-Bid-Build (Traditional Delivery)
The conventional project delivery method where the owner hires an architect to complete the design, the finished construction documents are sent to general contractors for competitive bidding, and the selected GC builds the project under a lump-sum or cost-plus contract. The phases are sequential: design is completed before the contractor is involved. This means the first real construction cost number does not appear until the design is finished, and by that point roughly 80% of project costs are already locked in by decisions that were never priced while they were being made.
Full guide: Why CMAR →
Design-Build
A delivery method where one entity provides both the architectural design and the construction under a single contract with the owner. The advantage is speed and single-point accountability. The trade-off is that the architect works for the builder, not for the owner, which compromises the architect's independence as a design advocate and quality watchdog. CMAR offers a middle path: the builder joins during design like design-build, but the architect holds a separate contract with the owner like traditional delivery.
Full guide: Why CMAR →
Lump-Sum Contract
A construction contract where the contractor agrees to complete the defined scope of work for a single fixed price. The owner does not see what anything actually costs, what the markup is, or whether they are overpaying for materials and subcontractors. The contractor profits from the spread between the lump-sum price and actual costs. On complex projects where scope is difficult to define precisely, lump-sum contracts incentivize contractors to bid low to win and recover margin through change orders.
Full guide: Construction Contracts →
Cost-Plus Contract
A construction contract where the owner reimburses the actual cost of the work plus a percentage markup as the contractor's fee. There is no ceiling on total cost, no benchmark for whether prices are competitive, and the contractor has no structural financial incentive to control costs because the markup grows as costs grow. Every dollar of cost overrun falls on the owner.
Full guide: Construction Contracts →
Owner's Representative (OR)
An advisor who acts on the owner's behalf during the construction process: monitoring progress, reviewing documentation, coordinating consultants, and flagging issues. The OR does not hold construction contracts, does not manage subcontractors, and does not carry financial risk for the project outcome. OR fees typically run 3-5% of construction cost. In a CMAR engagement, the CM fee of 10-12.5% covers both the advisory function and the construction management function under one contract.
Full guide: Construction Oversight →
Focused Engagement
A limited-scope construction management contract for a specific, technically complex problem: a retaining wall replacement, a foundation investigation and repair, a shoring program, a dewatering system, a seismic retrofit, or structural remediation. Focused engagements typically range from $75,000 to $500,000 in construction value and are particularly relevant for Los Angeles hillside properties where even small scopes involve engineering, permits, and multi-trade coordination that a single trade contractor cannot manage.
Full guide: Focused Engagements →
Prime Contract
The contract between the owner and the general contractor or construction manager. The prime contract consists of the Agreement (the deal-specific terms including scope, price, and schedule) and the General Conditions (the operational rules governing how the contract works). It is distinguished from subcontracts (between the GC/CM and trade contractors) and the owner-architect agreement (a separate contract for design and construction administration services). The prime contract defines the owner's rights, obligations, and financial exposure.
Full guide: Construction Contracts →
Subcontract
An agreement between the general contractor or construction manager and a specialty trade contractor to perform a specific scope of work. On a CMAR project, the CM holds all subcontracts directly. Each trade scope is competitively bid by three or more qualified subcontractors, bids are leveled for apples-to-apples comparison, and the subcontract is executed at the open-book market rate. The owner sees every subcontract and every subcontractor bid as part of the GMP assembly process.
AIA Contract Documents
Standardized construction contract forms published by the American Institute of Architects since 1888. The most commonly used on residential CMAR projects include A133 (CM as Constructor with GMP), A102 (Cost Plus Fee with GMP), A201 (General Conditions), and B101 (Owner-Architect Agreement). AIA documents represent over a century of industry practice and carry predictable legal meaning because courts have interpreted their provisions extensively. This interpretive history is one of their practical advantages over custom-drafted contracts.
Full guide: Construction Contracts →
A201 General Conditions
The AIA document that defines the operational rules governing how a construction contract works in practice. A201 covers how change orders are initiated and priced, what the architect's authority is during construction, what constitutes substantial completion, how disputes are resolved, the conditions for withholding payment, the contractor's responsibility for means and methods, and dozens of other procedural provisions. A201 is paired with the Agreement (A101, A102, or A133) to form the complete prime contract. The General Conditions deserve equal scrutiny to the Agreement because they govern how the project actually runs day to day.
Full guide: Construction Contracts →
Construction Change Directive (CCD)
A written order issued by the architect directing the contractor to proceed with a change in the work before the cost of the change has been agreed upon. Under AIA A201, a CCD authorizes the work to proceed while the price is negotiated, preventing schedule delays caused by pricing disputes. The contractor is obligated to perform the work and is compensated based on actual cost if the parties cannot agree on a fixed price. CCDs are used when a change is time-critical and waiting for a fully priced change order would delay the project.
Notice to Proceed (NTP)
A written instruction from the owner to the contractor authorizing the start of construction work. The NTP establishes the official commencement date of the contract time and triggers the contractor's obligation to begin mobilization and construction within the timeframe specified in the contract. On complex residential projects, the NTP is typically issued after the building permit is obtained, the builder's risk insurance is in place, and any preconditions specified in the contract have been satisfied.
Allowance
A defined dollar amount included in the contract or GMP for a scope of work that has not yet been fully specified. Allowances are commonly used for finish selections that the owner has not yet made at the time the GMP is set: tile, stone, plumbing fixtures, lighting fixtures, hardware, and appliances. The allowance establishes a budget placeholder. When the actual selection is made and priced, the difference between the allowance and the actual cost is processed as a GMP adjustment. Allowances that are set too low create the appearance of a lower GMP but generate change orders when real selections exceed the placeholder amount.
Unit Price
A pre-agreed price per unit of measurement for work whose total quantity is uncertain at the time of contracting. Common examples in residential construction include a price per linear foot of caisson drilling beyond the assumed depth, a price per cubic yard of soil export, or a price per square foot of additional shoring. Unit prices are established during pre-construction and locked into the GMP as a mechanism for adjusting the contract when actual field conditions differ from assumptions without requiring a full change order negotiation for each occurrence.
Time and Materials (T&M)
A billing method where the owner pays for actual labor hours at agreed-upon rates plus the actual cost of materials, typically with a markup for overhead and profit. T&M is used for work where the scope cannot be defined precisely enough to price as a lump sum, such as exploratory demolition, concealed condition investigation, or emergency repairs. On a CMAR project, T&M work is tracked in real time and reported to the owner as part of the open-book cost reporting. Extended use of T&M without converting to defined scope is a cost control risk.
Force Majeure
A contract provision that excuses performance delays caused by events beyond the control of either party: natural disasters, pandemics, government orders, labor strikes, material embargoes, and other unforeseeable events. Under most AIA contracts, force majeure events entitle the contractor to an extension of the contract time but not additional compensation. The distinction matters because a schedule delay caused by force majeure does not trigger liquidated damages, but the general conditions costs that accumulate during the delay are typically not recoverable by the contractor.
Performance Bond
A surety bond issued by a bonding company that guarantees the contractor will complete the project in accordance with the contract terms. If the contractor defaults, the surety either finds a replacement contractor to complete the work or compensates the owner for the cost of completion. Performance bonds are common on commercial projects and are increasingly required on residential projects above $3-5 million. The bond premium is typically 1-3% of the contract value and is a project cost paid by the owner. For projects above $3M, a performance bond provides meaningful financial protection against contractor default.
Full guide: Construction Contracts →
Payment Bond
A surety bond that guarantees the contractor will pay its subcontractors and material suppliers. If the contractor fails to pay, the surety pays the subcontractors, protecting the owner from mechanic's lien claims. Payment bonds are typically issued together with performance bonds and are particularly valuable on large residential projects where the owner's primary financial exposure from contractor default is not just the cost of completing the work but also the lien claims from unpaid subcontractors.
Indemnification
A contractual provision where one party agrees to hold the other party harmless from specified claims, damages, or liabilities. In construction contracts, the contractor typically indemnifies the owner against claims arising from the contractor's negligence or willful misconduct. California Civil Code Section 2782 limits indemnification provisions in construction contracts, prohibiting clauses that require the contractor to indemnify the owner for the owner's own active negligence. Understanding what your contract's indemnification clause actually covers, and what it does not, is important and warrants legal review.

Cost, Budget & Financial Structure

Hard Costs
The direct physical construction costs of a project: trade labor, materials, equipment, subcontractor contracts, and general conditions. When someone quotes a per-square-foot construction cost for a custom home in Los Angeles, they are typically referring to hard costs only. Hard costs do not include soft costs such as architectural and engineering design fees, permits, consulting, legal, or financing costs, which typically add 20-30% on top.
Full guide: Construction Costs in Los Angeles →
Soft Costs
Everything that is not physical construction: architectural and engineering design fees, permits and agency fees, geotechnical and environmental consulting, surveys, legal, insurance, and financing costs. On a complex residential project in Los Angeles, soft costs typically range from 20-30% of the hard construction cost. Architectural fees alone are typically 8-15% of construction cost. These costs should be budgeted from the start, not treated as surprises.
Full guide: Construction Costs in Los Angeles →
General Conditions (Cost Category)
The non-trade costs of running a construction project: project management staff, site supervision, temporary facilities and utilities, equipment and tools, safety and OSHA compliance, project insurance, cleanup, and site security. In a lump-sum contract, general conditions are bundled into the total price and invisible. In CMAR, they are itemized separately. On complex residential projects, general conditions typically range from 8-15% of the cost of work, depending on project duration and staffing requirements.
Full guide: Construction Costs in Los Angeles →
Construction Contingency
A budget reserve within the GMP covering unforeseen conditions not visible in the construction documents and not reasonably anticipatable at the time the budget was set. On new construction: 5-10%. On major renovations with unknown concealed conditions: 8-12%. Construction contingency is tracked and reported separately from owner contingency in a CMAR engagement.
Full guide: Budget Development & Cost Control →
Owner Contingency
A budget reserve held by the owner, separate from construction contingency, covering owner-directed changes, scope additions, and finish upgrades decided after the GMP is set. Typically 3-7% of the cost of work. When the owner decides to upgrade a material or add a feature after the GMP is established, the cost comes from owner contingency and is processed as a GMP amendment.
Bid Leveling
The process of normalizing competitive subcontractor bids to ensure an apples-to-apples comparison. When three electrical subcontractors bid on the same scope, their proposals include different exclusions, allowances, and interpretations. Bid leveling identifies these differences, adds back excluded scope, and adjusts the numbers so each bid covers the same work. On a typical project, bid leveling identifies $200,000 to $500,000 in exclusions that would have become change orders if the lowest raw bids were accepted without analysis.
Full guide: Budget Development & Cost Control →
Progressive Cost Modeling
The practice of developing the construction budget alongside the design rather than after it. At feasibility: plus or minus 20-25%. At schematic design: plus or minus 15%. At design development: plus or minus 10%. At construction documents: plus or minus 5% from leveled competitive bids. Each design milestone produces a corresponding budget milestone, and cost-driven design decisions are made while they are still fluid and inexpensive to change.
Full guide: Budget Development & Cost Control →
Retention (Retainage)
A percentage of each progress payment withheld by the owner as security for the contractor's completion of the work. Under California law for private works, retention is limited to 5% and is released upon final completion after punch list resolution, final inspections, Certificate of Occupancy issuance, and receipt of final lien waivers from all subcontractors and suppliers.
Full guide: Construction Contracts →
Shared Savings
In a CMAR engagement, if actual project costs come in below the Guaranteed Maximum Price, the difference is shared between owner and CM, most commonly at a 75/25 split. This creates a structural incentive for the CM to deliver under budget. The opposite of cost-plus, where the contractor benefits when costs increase.
Mechanic's Lien
A legal claim against a property filed by a contractor, subcontractor, or material supplier who has not been paid. Under California law, subcontractors and suppliers can place liens on the owner's property even if the owner paid the general contractor in full. The protection is collecting conditional and unconditional lien waivers from all subcontractors and suppliers with every payment cycle. In a CMAR engagement with open-book accounting, the owner sees every subcontractor payment and lien waiver as part of standard monthly reporting.
Full guide: Construction Contracts →
Schedule of Values
A detailed breakdown of the contract sum into individual line items for each trade and scope of work. The schedule of values is the basis for monthly pay applications: each month, the CM reports the percentage of completion for each line item, and the payment due is calculated from those percentages applied to the budgeted amounts. On a CMAR project, the schedule of values mirrors the GMP line items and provides the owner with granular visibility into where money is being spent.
Conditional Lien Waiver
A document signed by a subcontractor or material supplier waiving their right to file a mechanic's lien, conditional upon receipt of payment. The waiver becomes effective only when the payment clears. California law prescribes specific statutory forms for conditional waivers (Civil Code Section 8132 for progress payments, Section 8136 for final payment). Collecting conditional lien waivers from every subcontractor and supplier with every pay application is a standard practice in CMAR and the owner's primary protection against double-payment exposure.
Unconditional Lien Waiver
A document signed by a subcontractor or material supplier waiving their lien rights unconditionally, typically executed after payment has been received and cleared. Unconditional waivers for prior payment periods are collected with each new pay application, confirming that the subcontractor received and accepted the previous month's payment. The combination of conditional waivers at the time of billing and unconditional waivers confirming receipt creates a complete chain of lien protection for the owner.
Preliminary Notice (20-Day Notice)
A notice required under California law (Civil Code Section 8200) that subcontractors and material suppliers must send to the property owner within 20 days of first furnishing labor or materials to the project. The preliminary notice preserves the sender's right to file a mechanic's lien if they are not paid. Receiving a preliminary notice does not mean anything is wrong. It is a routine legal requirement, and on a complex residential project the owner will receive dozens of them. The notices are important because they identify every entity that has lien rights on the property, which is information the owner needs to verify that all parties are being paid.

Pre-Construction & Planning

Pre-Construction Services
Everything that happens between the decision to build and the start of physical construction: feasibility analysis, budget development, design-phase cost estimating, value engineering, constructability review, subcontractor qualification and bidding, schedule development, permitting strategy, and GMP assembly. Pre-construction typically takes 8-14 months on a complex residential project and is where the project's financial outcome is determined. The cost is typically included in the CM's fee of 10-12.5%.
Full guide: CMAR Deliverables →
Feasibility Study
An evaluation conducted before architectural design begins that determines whether a project is viable and what it will realistically cost. Covers site conditions, geotechnical indicators, zoning and regulatory constraints, permitting pathway, utility availability, environmental requirements, preliminary cost modeling, and risk assessment. Typically costs $15,000 to $40,000 for residential projects in Los Angeles.
Full guide: Project Feasibility →
Constructability Review
A systematic evaluation of construction documents by the CM to identify design details that will be difficult, expensive, or impossible to build as drawn. Covers structural connections, material availability, clearance conflicts between disciplines, access constraints, and sequencing issues. Problems identified during design cost virtually nothing to fix. The same problems discovered during construction can cost tens or hundreds of thousands in rework.
Value Engineering
A systematic review of the project design to identify cost reductions without compromising design intent, quality, or performance. Not about cutting corners. Examples include substituting structural systems where an alternative provides equal performance at lower cost, specifying domestically available materials that match the design intent, or revising MEP layouts to reduce distribution runs. Most effective during design development, before decisions are locked in.
Lot Due Diligence
The investigation process conducted before purchasing a lot to determine what can be built, what it will cost, and what the significant risks are. Includes geotechnical review, topographic survey, zoning analysis, regulatory overlay check, utilities assessment, tree survey, and preliminary cost model. Two adjacent hillside lots on the same street can differ by a million dollars or more in construction cost. Pre-purchase evaluation starts at approximately $17,500.
Full guide: Lot Due Diligence →
Schematic Design (SD)
The first major design phase, where the architect establishes the overall concept: building massing, floor plan layouts, basic structural approach, site placement, and general material direction. In CMAR, the CM provides the first assembly-based cost estimate at SD completion, narrowing the budget range to plus or minus 15%. The most cost-effective point to adjust scope because changes require revising concept sketches, not detailed construction documents.
Design Development (DD)
The second major design phase, refining schematic design into detailed drawings: specific structural systems, MEP layouts, material selections, window and door schedules, and interior details. In CMAR, the CM provides quantity-takeoff-based estimates with preliminary subcontractor pricing at DD completion, narrowing the budget to plus or minus 10%. The last practical opportunity for significant scope changes without incurring redesign costs on nearly complete construction documents.
Construction Documents (CD)
The final design phase producing the complete set of drawings and specifications from which the project will be built, permitted, and priced. Includes architectural plans, structural engineering, MEP drawings, landscape plans, civil engineering, and specifications. In CMAR, the CM solicits competitive subcontractor bids on the CDs, levels those bids, and assembles the Guaranteed Maximum Price.
Trade Pre-Qualification
The process of evaluating and selecting subcontractors who are invited to bid on each trade scope. Pre-qualification criteria include experience with similar project types and complexity, current workload and availability, financial capacity, safety record, and references from recent projects. Pre-qualification ensures that every bid the owner sees comes from a contractor who is actually capable of performing the work, not just the one who submitted the lowest number.
Parametric Estimate
A cost estimate based on broad parameters such as square footage, number of stories, and project type, applied against historical cost data for similar projects. Parametric estimates are appropriate at the feasibility stage when no design exists yet and provide a budget range at plus or minus 20-25% accuracy. They are useful for establishing whether a project is financially viable before investing in architectural design, but they are not a substitute for the detailed estimating that occurs during design phases.
Quantity Takeoff
The process of measuring and counting every material and labor quantity from the construction documents: linear feet of foundation, square feet of framing, cubic yards of concrete, number of fixtures, and so on. Quantity takeoffs are performed during design development and construction documents phases and form the basis for subcontractor bid packages and the GMP. The accuracy of the GMP is directly dependent on the completeness and precision of the quantity takeoff.

Foundations & Geotechnical

Caisson (Drilled Shaft)
A deep foundation element formed by drilling a cylindrical hole into the ground, inserting a reinforcing steel cage, and filling with concrete. Caissons transfer building loads through weak surface soils to competent bedrock below. On hillside lots in Pacific Palisades, Bel Air, Malibu, and Palos Verdes, caissons typically reach 20 to 40 feet or more. Residential caissons are typically 18 to 36 inches in diameter. Foundation costs: $200,000 to $600,000, with complex sites exceeding $1 million.
Full guide: Deep Foundation Costs →  |  Foundation Systems →
Grade Beam
A reinforced concrete beam connecting the tops of caissons or piles, tying deep foundation elements into a unified structural system. Grade beams distribute loads horizontally while caissons transfer loads vertically. On hillside projects, grade beams also resist lateral loads from the slope. Typically adds $80,000 to $200,000 to the foundation cost.
Full guide: Foundation Systems →
Spread Footing
A shallow foundation element, typically a rectangular concrete pad, that distributes building loads over a wide area of soil near the surface. Suitable for flat lots with adequate bearing capacity at shallow depths. On most hillside lots in Los Angeles, spread footings are insufficient because bearing soil is too deep, slopes create lateral loads shallow footings cannot resist, or soil conditions vary dramatically across the site. Flat-lot spread footing foundations: $60,000 to $120,000.
Full guide: Foundation Systems →
Mat Slab (Raft Foundation)
A thick reinforced concrete slab that spans the entire building footprint and distributes loads over the full area of the foundation. Mat slabs are used when individual footings would be so large that they would overlap, when the soil has low or variable bearing capacity that benefits from load distribution over a larger area, or when the building has a basement and the slab serves as both the foundation and the basement floor. On hillside lots with subterranean levels, mat slabs are often combined with caissons for a hybrid foundation system.
Geotechnical Report (Soils Report)
A subsurface investigation performed by a licensed geotechnical engineer documenting soil conditions, bearing capacity, groundwater, slope stability, and seismic parameters. LADBS requires an approved geotechnical report before structural engineering can proceed and before building permits are issued. Costs $8,000 to $25,000. On hillside lots, soil conditions can change dramatically across short distances, with bedrock depth varying by 10 or more feet between borings 20 feet apart. Currently taking up to 16 weeks from engagement to delivery.
Full guide: Foundation Systems →
Bearing Capacity
The maximum pressure a soil or rock formation can support without failure or excessive settlement. Expressed in pounds per square foot (psf). Alluvial soils in flatland areas might provide 1,500-3,000 psf. Bedrock on hillside sites can provide 8,000-15,000 psf or more, but only at the depth where competent material is encountered. The geotechnical report determines bearing capacity; the structural engineer designs the foundation to deliver loads within those limits.
Differential Settlement
Uneven foundation movement where different parts of the structure settle at different rates. Visible symptoms: doors that stick, cracks radiating from window corners, uneven floors. Common on older homes in Pacific Palisades, Hollywood Hills, and Bel Air where original foundations may be undersized or water infiltration has weakened bearing soil. Remediation: underpinning with steel piers or helical piles. Cost: $80,000 for isolated underpinning to $500,000+ for comprehensive remediation.
Full guide: Structural Remediation →
Underpinning
A foundation strengthening method that extends an existing foundation to greater depth or transfers its loads to more competent bearing material. Common methods: push piers (hydraulically driven steel segments pressed to bedrock) and helical piles (steel shafts screwed into the ground beneath the footing). The standard remediation for differential settlement, foundation settlement, and situations where the original foundation bears on soil that has lost capacity.
Full guide: Shoring & Underpinning →
Helical Pile
A deep foundation element consisting of a steel shaft with helical plates welded to it, screwed into the ground using hydraulic torque equipment until it reaches the target bearing stratum. Generates minimal vibration, produces no spoils requiring export, and can be installed in tight access conditions common on hillside lots. Installed to a specified torque value that correlates to verified bearing capacity. Commonly used for underpinning existing foundations and for new foundations where access prevents conventional drilling equipment.
Push Pier (Resistance Pier)
A foundation repair system where steel pipe segments are hydraulically driven through the existing footing into competent bearing material below. The building's own weight provides the reaction force for driving the piers. Once the piers reach adequate bearing, hydraulic jacks lift the settled portion of the structure back toward its original elevation. Push piers are the standard remediation for active differential settlement where the structure needs to be releveled, not just stabilized.
Post-Tensioning
A method of reinforcing concrete by tensioning steel cables (tendons) embedded in the slab or beam after the concrete has cured. The tensioned cables compress the concrete, significantly increasing its resistance to cracking and deflection. Post-tensioned slabs are commonly used on expansive clay soils in Los Angeles because they resist the differential movement caused by clay shrink-swell cycles better than conventionally reinforced slabs. Post-tensioned foundations are also used for mat slabs on hillside projects where spanning capability is critical.
Rebar Cage
An assembly of reinforcing steel bars tied together into a cylindrical or rectangular framework, inserted into a drilled caisson hole or a formed concrete element before concrete is placed. The rebar cage provides tensile strength that the concrete alone cannot deliver. On caissons, the cage is designed by the structural engineer to resist both vertical loads and lateral forces from the slope. Rebar cage fabrication and placement must be inspected by LADBS before concrete can be poured.
Concrete Core Sampling
A non-destructive testing method where a cylindrical sample is drilled from an existing concrete element, such as a foundation, slab, or retaining wall, and tested in a laboratory for compressive strength, density, and condition. Core sampling is the primary method for evaluating whether a fire-damaged foundation retains adequate structural capacity. The results tell the structural engineer whether the concrete's compressive strength meets the original design requirements or has been degraded by heat exposure.
Full guide: Foundation Certification →
Tremie Pipe
A method of placing concrete underwater or in a water-filled caisson hole. A sealed pipe is inserted to the bottom of the hole, and concrete is pumped through the pipe from the bottom up, displacing the water as it fills the hole. Tremie placement prevents the concrete from segregating or being diluted by contact with water during the pour. On hillside sites with seasonal groundwater, encountering water in caisson holes during drilling is common. Tremie placement with higher-PSI concrete mix designs ensures the caisson achieves full structural capacity even in wet conditions.
Full guide: Hillside Construction →
Exploratory Boring
A hole drilled into the ground by a geotechnical engineer to collect soil and rock samples at various depths for laboratory testing. Standard geotechnical investigations include 3-4 borings; on complex hillside sites, additional borings reduce the risk of encountering unexpected subsurface conditions during construction. Each boring provides data at one specific point; soil conditions between borings must be interpolated. Additional borings during design typically cost $5,000 to $15,000 and can prevent far more expensive surprises during construction.
Expansive Clay (Expansion Index)
Soils containing clay minerals that absorb water and swell, then shrink as they dry. The Expansion Index (EI) is a laboratory test that quantifies this behavior. Soils with an EI above 50 are considered expansive and require special foundation design, such as deepened footings, post-tensioned slabs, or moisture barriers, to accommodate the volume changes. Expansive clay is common across many Los Angeles hillside areas and is a frequent driver of foundation distress on older homes where the original foundation was not designed for the soil's expansion characteristics.
Full guide: Foundation Systems →
Colluvium
Loose, unconsolidated material that has accumulated at the base of slopes through gravity-driven movement: weathered rock, soil, and organic debris that has slid, crept, or washed downhill over time. Colluvium is generally unsuitable for bearing and must typically be removed or bypassed with deep foundations. Its presence indicates ongoing slope activity, and its depth and extent are determined by the geotechnical investigation.
Alluvium
Material deposited by flowing water, including sand, gravel, silt, and clay in varying mixtures. Alluvial soils are found in flatland and valley areas of Los Angeles and can provide adequate bearing capacity depending on their composition and density. Alluvium is generally more predictable than hillside soils but can be interlayered with less competent material that requires careful evaluation.
Old Fill (Pre-1963 Fill)
Earth material placed before 1963, which is classified under the Los Angeles Municipal Code as uncertified because it predates modern grading code requirements. Its composition, compaction, and depth are unknown until investigated. Old fill cannot be assumed to have any bearing capacity. When encountered, the response is typically removal and recompaction (R&R) or deep foundations that bypass the fill entirely. Remediation costs when old fill is encountered typically range from $200,000 to over $1 million depending on volume and site access.
Full guide: Hillside Construction →
Removal and Recompaction (R&R)
The process of excavating uncertified or unsuitable fill material, exporting it from the site, and replacing it with properly compacted, tested fill that meets current grading code requirements. On hillside sites, R&R is complicated by constrained access, haul route requirements, restricted hauling hours, and the need for temporary shoring while the excavation is open. Every lift of replacement fill requires compaction testing and soils engineer observation.
NAVD88 Datum
The North American Vertical Datum of 1988, the standard vertical reference system used by surveyors and engineers to establish consistent elevation measurements. On hillside projects, it is critical that the topographic survey, geotechnical boring logs, and structural plans all reference the same vertical datum. When different consultants use different reference points, foundation designs end up based on assumed elevations that do not match field conditions, leading to costly redesign during construction.

Structural Systems & Engineering

Moment Frame
A structural framing system that resists lateral forces through rigid connections between beams and columns. The beam-to-column joints transfer bending forces, allowing the frame to flex and absorb earthquake or wind loads without diagonal bracing or shear walls. Steel moment frames are common on high-end hillside homes because they allow large open spans and floor-to-ceiling glass. The 1994 Northridge earthquake exposed critical vulnerabilities in welded moment frame connections, leading to significantly revised detailing requirements.
Full guide: Seismic Risk & Retrofit →
Shear Wall
A structural wall designed to resist lateral forces from wind and earthquakes by acting as a rigid plane. The primary lateral force-resisting system in most residential construction. Can be plywood over wood framing, reinforced concrete, reinforced masonry, or steel plate. Placement, length, and construction details are critical to earthquake performance. Insufficient or improperly detailed shear walls are one of the most common structural deficiencies in pre-1978 homes.
Diaphragm
A horizontal structural element, typically a floor or roof assembly, that transfers lateral forces to the vertical lateral force-resisting elements (shear walls or moment frames). In wood-frame residential construction, the plywood sheathing on the floor and roof acts as the diaphragm. The diaphragm must be adequately connected to the shear walls below and above to create a continuous load path from the roof to the foundation. Inadequate diaphragm connections are a common failure point in older homes during earthquakes.
Hold-Down
A steel hardware device that connects the end of a shear wall to the foundation or to the framing below, resisting the uplift forces generated when lateral loads try to overturn the wall. Hold-downs are critical structural connections in seismic design. On multi-story homes, hold-downs at every shear wall must be continuous from the roof down to the foundation, creating an unbroken chain of tension resistance. Improperly installed or missing hold-downs are a common structural deficiency identified during seismic evaluations of older homes.
Simpson Tie (Structural Connector Hardware)
Prefabricated steel connectors manufactured by Simpson Strong-Tie, the dominant manufacturer of structural connection hardware for wood-frame construction. Simpson ties include joist hangers, hurricane ties, hold-downs, straps, and a wide range of connectors that join framing members and transfer loads between elements. Modern building codes require engineered connectors at virtually every critical framing joint. "Simpson tie" is commonly used as a generic term for any structural framing connector, similar to how "Band-Aid" refers to any adhesive bandage.
Structural Engineer
A licensed professional engineer who designs structural systems: foundations, framing, lateral force-resisting systems, retaining walls, and connections. In California, structural engineers hold a specific SE license authorizing them to design structures in seismic zones, a scope that exceeds a civil engineer's (PE) authority for certain structure types. The structural engineer designs the bridge between the site's geotechnical conditions and the architect's design vision.
Geotechnical Engineer
A licensed professional engineer who investigates subsurface conditions and provides recommendations for foundation design, grading, slope stability, drainage, and seismic parameters. On hillside lots in Los Angeles, the geotechnical engineer is typically the first consultant engaged and the last to sign off, because their recommendations govern the structural engineer's design, the civil engineer's grading plan, and the construction manager's means and methods.
Full guide: Foundation Systems →
Civil Engineer
A licensed professional engineer who designs the site infrastructure: grading plans, drainage systems, utility connections, retaining walls (in some cases), access roads, and stormwater management. On hillside projects, the civil engineer works closely with the geotechnical engineer to design grading that complies with the Baseline Hillside Ordinance's Maximum Grading Quantities while achieving the required building pad elevations. The civil engineer's grading plan is the basis for the grading permit application.
RFI (Request for Information)
A formal written question from the contractor or CM to the architect or engineer requesting clarification of the construction documents. Generated when drawings contain ambiguities, conflicts between disciplines, missing details, or when field conditions differ from what was drawn. On complex residential projects, 50 to 200+ RFIs are common. The speed and quality of RFI responses directly affects the construction schedule.
Submittal
A document submitted by the contractor to the architect for review before a material or system is fabricated or installed. Includes shop drawings, product data sheets, material samples, and mock-ups. The architect reviews each submittal to verify conformance with design intent. On complex residential projects, 200 to 500+ submittals cover everything from structural steel connections to tile selections to custom millwork.
Structural Steel Erection
The process of assembling a structural steel frame on site: setting columns on anchor bolts embedded in the foundation, placing beams and girders, bolting or welding connections, and installing metal decking for floors and roof. Structural steel is common on high-end hillside homes in Los Angeles because it allows long spans, open floor plans, and cantilevered elements that wood framing cannot achieve. Steel erection requires a crane, an ironworker crew, and a special inspector who verifies bolted and welded connections against the structural engineer's specifications.
Special Inspector (Deputy Inspector)
A qualified individual hired by the owner to observe and verify that specific construction operations comply with the approved plans and applicable codes. LADBS requires special inspection for structural steel welding, high-strength bolting, concrete placement, reinforcing steel placement, masonry, and other critical operations. The special inspector does not direct the work; they observe and document whether it meets the requirements. Special inspection reports are submitted to LADBS as part of the project record and are required before the Certificate of Occupancy is issued.
Concrete PSI (Compressive Strength)
The measure of concrete's ability to resist compression, expressed in pounds per square inch. Standard residential concrete is typically 2,500 to 3,000 PSI. Structural elements like caissons, grade beams, and retaining walls often require 4,000 to 5,000 PSI or higher. When concrete is placed in wet conditions using tremie methods, higher PSI mix designs are specified to compensate for potential water contamination during placement. Concrete strength is verified through field testing: cylinders are cast during each pour and tested in a laboratory at 7 and 28 days.

Earthwork, Grading & Shoring

Shoring
A temporary earth retention system used during construction to hold back soil while permanent structures are built. Required whenever excavation goes deep enough to undermine adjacent structures, property lines, or slope stability. On hillside sites in Los Angeles, shoring is nearly always required. Common methods: soldier pile and lagging, shotcrete walls, and sheet piling. Costs: $150,000 to $500,000+ depending on depth, retained height, and soil conditions. Must be designed by a licensed engineer and approved by LADBS before excavation.
Full guide: Shoring & Underpinning →
Soldier Pile and Lagging
The most common temporary shoring system on hillside residential projects in Los Angeles. Steel H-piles or wide-flange beams are driven or drilled into the ground at 6 to 8 foot spacing. As excavation proceeds, horizontal timber planks or concrete panels are placed between the piles to retain the soil. Preferred on residential hillside projects because it can be installed with compact equipment in constrained access conditions with minimal vibration.
Full guide: Shoring & Underpinning →
Shotcrete
Concrete or morite pneumatically applied at high velocity onto a surface. In hillside construction, shotcrete is used for temporary shoring walls (sprayed over reinforcing mesh against the excavated soil face), permanent retaining walls, swimming pool shells, and slope stabilization. Shotcrete can be applied to irregular surfaces and in areas where conventional formwork would be difficult or impossible to construct. The two application methods are dry-mix (water added at the nozzle) and wet-mix (pre-mixed before pumping), with wet-mix being more common on residential projects.
Sheet Piling
Interlocking steel sheets driven into the ground to form a continuous wall for temporary earth retention or permanent waterfront structures. Sheet piling creates a watertight barrier, making it useful where groundwater control is required during excavation. Less common than soldier pile and lagging on residential hillside projects because it generates significant vibration during driving, which can damage adjacent structures. Used primarily on projects near waterfronts or where groundwater cutoff is the primary concern.
Tieback Anchor
A tensioned steel cable or bar drilled through a shoring wall into the soil or rock behind it, anchored at depth, and tensioned to provide additional lateral support to the shoring system. Tiebacks allow shoring walls to retain greater heights without becoming impractically thick. On hillside sites where the shoring wall approaches the property line, tiebacks may extend beneath the neighbor's property, requiring an easement or license agreement, which is a common source of neighbor coordination complexity on hillside projects.
Grading
The process of reshaping the ground surface through excavation (cutting) and filling to create building pads, access roads, drainage patterns, and final site contours. On hillside lots in Los Angeles, grading is heavily regulated by the Baseline Hillside Ordinance, which sets Maximum Grading Quantities based on lot size and slope. Any excavation, fill, or earth movement in a designated Hillside Grading Area requires a grading permit with an approved geotechnical report, haul route approval, and building permit coordination.
Full guide: Grading Limits →
Maximum Grading Quantities (MGQ)
The maximum volume of earth that can be cut, filled, imported, or exported on a hillside lot under the Baseline Hillside Ordinance. MGQs vary by lot size and slope band and are often the binding constraint on hillside projects. When MGQs are too low for a conventional cut-and-fill approach, the foundation system must be designed to work with the existing grade rather than reshape it, typically requiring caissons drilled through the slope to bedrock with grade beams spanning between them.
Full guide: Grading Limits →
Haul Route
The approved trucking path for importing or exporting earth material. In Los Angeles, haul routes on hillside projects must be approved by LADBS and are subject to operating hour restrictions. In the Bel Air-Beverly Crest HCR district, hauling is restricted to 9 AM to 3 PM, Monday through Friday only, creating a 6-hour daily window that becomes a primary schedule driver on projects requiring significant grading.
Full guide: Grading Limits →
Retaining Wall
A structural wall holding back earth at a grade change. On hillside sites, required on the uphill side of building pads, the downhill side where the pad is cantilevered, and anywhere the project modifies existing grade. Must be designed by a structural engineer based on geotechnical data and must include drainage to prevent hydrostatic pressure buildup. Costs: $200,000 to $800,000+ depending on height, length, and conditions. Walls over 4 feet in retained height require a building permit.
Full guide: Retaining Walls →
Hydrostatic Pressure
The pressure exerted by water against a surface due to the weight of the water above it. In construction, most relevant behind retaining walls and against below-grade walls, where groundwater creates pressure that drives moisture through concrete, degrades membranes, and can structurally overload walls. Hydrostatic pressure buildup behind retaining walls is one of the most common causes of wall failure in Los Angeles. Mitigation: drainage system behind the wall with perforated pipe, drainage aggregate, and filter fabric.
Full guide: Waterproofing →  |  Retaining Walls →
Cut and Fill
The earthwork process of excavating soil from one area (cut) and placing it in another (fill) to create level building pads and drainage grades. Balanced cut and fill eliminates the need for export or import. On hillside lots, achieving balance is often impossible due to site geometry and BHO grading limits, so export is required. Export costs include trucking, dump fees, and the haul route approval process.
Slope Stability
The ability of a hillside to resist failure under its own weight, applied loads, seismic forces, and groundwater changes. Evaluated by the geotechnical engineer and determines whether a lot is buildable, what foundation system is required, and what retaining structures are necessary. Loss of vegetation from fire significantly reduces slope stability because plant roots provide soil cohesion. This is why LADBS created PGRAZ designations after the 2025 Palisades fires.
Full guide: Hillside Construction →
Surcharge Loading
Additional load applied to the soil behind a retaining wall from structures, vehicles, stored materials, or adjacent buildings. Surcharge increases the lateral earth pressure the wall must resist and must be accounted for in the structural design. A retaining wall that is adequate without surcharge may be undersized if a driveway, swimming pool, or building is later constructed on the retained soil above it. This is a common issue in neighbor disputes when one property's construction adds surcharge to the other property's retaining wall.
Compaction Testing
Field testing performed by the geotechnical engineer or their technician to verify that fill material has been compacted to the density specified in the grading plan, typically 90-95% of the maximum dry density determined by laboratory testing. Every lift of fill placed during grading must be tested and documented. On hillside projects where fill supports structural elements, compaction test results are submitted to LADBS as part of the project record. Inadequately compacted fill is one of the most common causes of foundation settlement.

Waterproofing & Drainage

Subdrain (French Drain)
A subsurface drainage system consisting of perforated pipe surrounded by drainage aggregate and wrapped in filter fabric, installed below grade to intercept and redirect groundwater before it reaches the foundation or builds pressure behind retaining walls. The primary defense against hydrostatic pressure and below-grade water intrusion on hillside properties. On hillside properties in Brentwood, Bel Air, and Pacific Palisades, subdrain installation as part of a dewatering program can cost $200,000 to $400,000.
Full guide: Waterproofing →
Waterproof Membrane
A barrier applied to below-grade concrete walls and slabs to prevent water penetration. Types: fluid-applied elastomeric coatings, sheet-applied membranes (self-adhering modified bitumen or thermoplastic), and bentonite clay panels. The membrane is one component of a complete system that also includes drainage board, subdrain, and proper grading. Applying a membrane without addressing drainage is a surface-level fix that typically fails within a few years.
Full guide: Waterproofing →
Drainage Board
A composite sheet installed over the waterproof membrane on below-grade walls. A dimpled plastic core creates an air gap between the membrane and backfill soil, with filter fabric on the soil side. Water runs down the air gap to the subdrain rather than pooling against the membrane. Protects the membrane during backfill, provides a drainage path, and extends the system's effective life. Standard component of any properly designed below-grade waterproofing assembly.
Dewatering
The process of removing or redirecting groundwater from a construction site or existing structure. Can be temporary during construction (well points, sump pumps) or permanent (engineered subdrain systems). On hillside properties with water intrusion, a comprehensive dewatering program typically involves exterior excavation, subdrain installation, membrane application, drainage aggregate backfill, and interior restoration. Requires civil engineering, possibly geotechnical engineering, multiple trades, permits, and careful sequencing.
Full guide: Waterproofing →
Building Envelope
The complete boundary between the conditioned interior and the exterior environment: roof, walls, windows, doors, foundation, and all connections between them. Must resist water, air, heat transfer, and vapor transmission while accommodating structural movement. On hillside homes, the envelope is particularly critical because below-grade walls contact soil and groundwater, hillside exposure subjects walls to driven rain, and temperature differentials between sun-exposed and shaded sides create moisture migration patterns.
Full guide: Waterproofing →
Weather-Resistive Barrier (WRB)
A material installed behind the exterior cladding (stucco, siding, stone) that prevents bulk water from reaching the structural sheathing and framing. The WRB is the last line of defense in a wall assembly. Traditional WRBs include building paper (two layers of Grade D kraft paper behind stucco, per code) and housewrap (Tyvek, etc.). Modern high-performance WRBs include fluid-applied membranes that create a seamless barrier without lap joints. WRB failure is one of the most common and expensive building envelope defects in the Los Angeles residential market.
Full guide: Waterproofing →
Flashing
Sheet metal or membrane material installed at transitions and penetrations in the building envelope to direct water away from vulnerable joints: where a roof meets a wall, where a window or door frame meets the wall assembly, where a deck attaches to the building, and at any change in material or plane. Flashing failures are the number one cause of water intrusion in residential construction. The flashing system must be integrated with the WRB in the correct sequence (shingled from bottom to top) so that water always flows outward and downward, never behind the barrier.
Full guide: Waterproofing →
Weep Screed
A perforated metal channel installed at the base of a stucco wall assembly, typically 4 inches above grade, that allows moisture within the wall cavity to drain out and prevents water from wicking up into the wall from below. California Building Code requires weep screed on all stucco wall assemblies. Missing or improperly installed weep screed traps moisture inside the wall cavity, leading to hidden wood rot, mold growth, and structural degradation that can go undetected for years.
Full guide: Waterproofing →
Rain Screen
A wall assembly design that creates a ventilated air gap between the exterior cladding and the weather-resistive barrier. The air gap allows any water that penetrates the cladding to drain down and out rather than being trapped against the WRB. Rain screen assemblies also promote evaporative drying of the wall cavity. They represent current best practice for high-performance building envelopes, particularly on coastal and hillside properties in Los Angeles where wind-driven rain exposure is significant.
Capillary Action
The ability of water to move through narrow spaces against gravity due to surface tension forces. In construction, capillary action draws moisture upward through concrete, mortar, and porous materials. A concrete slab in contact with wet soil will wick moisture upward through the slab and into the finish flooring above it. Capillary breaks, typically a polyethylene vapor barrier beneath the slab and drainage aggregate below that, interrupt this moisture path. Capillary action is also responsible for moisture migration through masonry retaining walls and through mortar joints in stone veneer.
Full guide: Waterproofing →
Vapor Barrier (Vapor Retarder)
A material that restricts the diffusion of water vapor through a building assembly. Commonly a polyethylene sheet installed beneath concrete slabs to prevent soil moisture from migrating upward, or a membrane within a wall assembly to control condensation. The distinction between a vapor barrier (very low permeability) and a vapor retarder (reduced but not zero permeability) matters in building science because overly restrictive vapor barriers in the wrong location can trap moisture and cause more damage than they prevent.
Positive-Side vs. Negative-Side Waterproofing
Positive-side waterproofing is applied to the exterior face of the wall, between the concrete and the soil, blocking water before it enters the structure. Negative-side waterproofing is applied to the interior face, managing water that has already penetrated the concrete. Positive-side is always preferred for new construction because it keeps water out of the concrete entirely. Negative-side is used for remediation when accessing the exterior face is impractical, such as an existing below-grade space where exterior excavation is prohibitively expensive or physically impossible.
Full guide: Waterproofing →
Well Point
A small-diameter pipe with a screened intake, driven or jetted into the ground and connected to a vacuum pump to lower the groundwater table in a localized area during construction. Well point systems are used for temporary dewatering when excavation extends below the water table, allowing foundation and utility work to proceed in dry conditions. On hillside sites with seasonal perched water, well points may be needed during the wet season to keep excavations workable.

Roofing & Building Enclosure

Standing Seam Metal Roof
A metal roofing system where long panels run vertically from ridge to eave, joined by raised interlocking seams that stand above the flat panel surface. The seams are the primary water-shedding mechanism: they elevate the connection points above the water flow path. Standing seam roofs are common on high-end residential projects in Los Angeles because they are durable, low-maintenance, fire-resistant, and accommodate thermal expansion through concealed clips that allow the panels to move. They are one of the most reliable roofing systems for hillside homes where wind exposure and fire resistance are primary concerns.
TPO (Thermoplastic Polyolefin)
A single-ply membrane roofing system used on flat and low-slope roofs. TPO membranes are heat-welded at the seams, creating a monolithic waterproof surface. Common on residential projects with flat roof sections, rooftop decks, or green roof assemblies. TPO is typically white, which reflects solar heat and contributes to energy code compliance. The membrane is mechanically attached or fully adhered to the roof substrate and must be properly detailed at all penetrations, drains, and edge conditions.
Modified Bitumen
A multi-layer asphalt-based roofing system used on flat and low-slope roofs. Consists of modified asphalt sheets reinforced with fiberglass or polyester, applied in overlapping layers that are torch-applied, self-adhered, or mopped with hot asphalt. Modified bitumen provides redundancy through multiple layers and is a reliable system for residential flat roofs. It is less reflective than TPO but has a long track record of performance when properly installed and maintained.
Roof Deck
The structural substrate beneath the roofing material: plywood or OSB sheathing on wood-framed roofs, concrete on post-tensioned or cast-in-place roof structures, or metal decking on steel-framed structures. The roof deck must be structurally adequate to support the roofing system, any rooftop equipment, and applicable live loads. On hillside homes with rooftop decks, the roof deck serves double duty as both the structural substrate for the waterproofing membrane and the base for the pedestrian surface above it.
Curtain Wall
A non-structural exterior wall system, typically aluminum-framed glass, that is hung from the building's structural frame rather than bearing any structural load. Curtain walls are the dominant glazing system on high-end hillside homes in Los Angeles where floor-to-ceiling glass and expansive views are primary design features. The system must resist wind loads, water infiltration, air leakage, and thermal transfer while accommodating building movement. Curtain wall systems are engineered, fabricated, and installed as a specialty trade scope, and their cost, lead time, and installation sequence are among the most significant variables on projects with extensive glazing.
Low-E Glass
Glass with a microscopically thin metallic coating that reduces the amount of infrared and ultraviolet radiation passing through the glass while allowing visible light to transmit. Low-E coatings reduce solar heat gain in cooling-dominated climates like Los Angeles, improving energy performance and helping meet California's Title 24 energy code requirements. Different Low-E coatings are optimized for different orientations: south and west-facing glass benefits from coatings that reject solar heat, while north-facing glass can use coatings that allow more solar gain.
Thermal Bridging
Heat transfer through a building element that has significantly higher thermal conductivity than the surrounding assembly, creating a pathway for heat to bypass the insulation. Common examples: steel studs in an insulated wall, concrete slab edges that extend through the building envelope, and window frames that conduct heat between interior and exterior. Thermal bridges reduce the effective insulation value of the assembly and can cause condensation on interior surfaces. Current California energy code increasingly requires continuous insulation strategies that interrupt thermal bridges.
R-Value
A measure of a material's resistance to heat flow. Higher R-values indicate better insulating performance. California's Title 24 energy code specifies minimum R-values for walls, roofs, and floors based on climate zone. Los Angeles falls in Climate Zone 8 or 9 depending on location, with typical minimum requirements of R-13 to R-21 for walls and R-30 to R-38 for roofs. The effective R-value of an assembly depends not only on the insulation itself but on thermal bridging, air leakage, and installation quality.
Air Barrier
A system of materials and connections designed to prevent uncontrolled air movement through the building envelope. Air leakage accounts for a significant portion of a building's energy loss and moisture problems. The air barrier must be continuous across the entire building envelope, which means it must be detailed at every transition: where the wall meets the roof, where the wall meets the foundation, at every window and door opening, and at every penetration. Modern high-performance residential construction increasingly treats the air barrier as a distinct system that is tested for continuity before the building is enclosed.
Stucco (Three-Coat and One-Coat)
A cementitious plaster system applied to exterior walls as weather protection and finish surface. Traditional three-coat stucco consists of a scratch coat, a brown coat, and a finish coat applied over two layers of Grade D building paper and metal lath. One-coat stucco is a polymer-modified system applied in a single thicker layer over a single layer of WRB. Three-coat is more durable and more forgiving of substrate irregularities. One-coat is faster and less expensive but more sensitive to installation quality. Both systems depend entirely on the WRB and flashing behind them for actual waterproofing; the stucco itself is not waterproof.

MEP Systems (Mechanical, Electrical, Plumbing)

HVAC (Heating, Ventilation, and Air Conditioning)
The mechanical systems that control a building's interior temperature, humidity, and air quality. On custom residential projects in Los Angeles, HVAC is typically the single largest MEP trade scope, ranging from $150,000 to $500,000+ depending on the size of the home, the number of zones, and the system type. System selection (ducted central air, ductless mini-splits, radiant, or hybrid systems) affects not only the mechanical cost but also the framing, ceiling heights, and architectural detailing throughout the house.
Manual J (HVAC Load Calculation)
The industry-standard method for calculating the heating and cooling loads of a residential building, published by the Air Conditioning Contractors of America (ACCA). Manual J determines how much heating and cooling capacity the HVAC system needs based on the building's size, orientation, insulation levels, window area and type, occupancy, and climate zone. California's Title 24 energy code requires that HVAC equipment be sized based on load calculations, not rules of thumb. Oversized equipment wastes energy and fails to control humidity; undersized equipment cannot maintain comfort.
Mini-Split (Ductless System)
A heating and cooling system consisting of an outdoor compressor/condenser unit connected to one or more indoor air handling units by refrigerant lines, without ductwork. Mini-splits provide individual zone control, are highly energy-efficient, and eliminate the space and framing requirements of a ducted system. They are increasingly popular on renovations where adding ductwork would require significant ceiling and wall modifications, and on new construction where the architect wants to eliminate the architectural impact of duct runs and ceiling drops.
Radiant Floor Heating
A heating system where warm water circulates through tubing embedded in the floor slab or subfloor assembly, radiating heat upward through the floor surface. Radiant heating is silent, eliminates forced-air drafts, and provides even heat distribution. Common on high-end residential projects in Los Angeles, particularly in bathrooms, kitchens, and living areas with stone or tile flooring that would otherwise feel cold. The system requires a dedicated boiler or heat pump, a manifold for zone control, and careful coordination with the structural and finish floor assemblies.
Electrical Panel (Service Panel)
The main distribution point where electrical power from the utility enters the building and is divided into individual circuits. Panel capacity is measured in amperes (amps). Most older homes have 100-200 amp service. Modern custom homes typically require 400-600+ amp service to support HVAC, kitchen equipment, EV charging, pool and spa equipment, lighting, and home automation. Upgrading electrical service on an existing home requires coordination with LADWP and can have a 4-8 month lead time, making it one of the long-lead items that should be initiated during design, not during construction.
Low-Voltage Wiring
Wiring that carries signals rather than power: network data (Cat 6/6A ethernet), audio/video distribution, security and alarm systems, intercom, and control system communication. Low-voltage wiring is run separately from electrical power wiring and terminates at a structured wiring panel or network rack. On custom homes, the low-voltage scope is often comparable in complexity to the electrical scope, and coordination between the low-voltage contractor, the electrician, and the home automation integrator is critical during the rough-in phase.
Structured Wiring
A centralized wiring infrastructure where all low-voltage cables (data, audio, video, security, control) are run to a single distribution point, typically a structured media panel or equipment closet. Structured wiring allows any outlet in the house to serve any function and simplifies system upgrades because the physical wiring infrastructure is separate from the equipment connected to it. Current best practice is to run Cat 6A ethernet to every room and to every location where a TV, camera, access point, or control device will be installed.
PEX (Cross-Linked Polyethylene)
A flexible plastic tubing used for water supply lines in residential construction. PEX has largely replaced copper piping for interior water distribution because it is less expensive, faster to install, resistant to corrosion, and less susceptible to freeze damage. PEX can be run in long continuous lengths with fewer fittings, reducing the number of potential leak points. It is available in different types (PEX-A, PEX-B) with different expansion and connection characteristics.
Sewer Lateral
The underground pipe connecting a building's plumbing system to the public sewer main in the street. The property owner is responsible for the lateral from the building to the public sewer connection. On hillside properties, sewer laterals can be long, steeply graded, and difficult to access for repair. Older laterals may be clay pipe that has deteriorated, shifted, or been infiltrated by tree roots. Lateral replacement is a common concealed-condition discovery on renovations of older hillside homes and can add $15,000 to $50,000+ to the project scope.
Rough-In
The phase of MEP installation where pipes, ducts, wires, and conduit are run through the framing before walls and ceilings are closed up. Rough-in must be completed and inspected by LADBS before insulation and drywall can proceed. On a complex residential project, the rough-in phase involves the plumber, electrician, HVAC contractor, low-voltage contractor, and fire sprinkler contractor all working simultaneously within the same wall and ceiling cavities. Coordination during rough-in determines whether systems fit within the available space or create conflicts that require field modifications.
Trim-Out (Finish Phase)
The phase of MEP installation where visible fixtures and devices are installed after walls, ceilings, and finishes are complete: light fixtures, switches, outlets, plumbing fixtures, faucets, shower valves, thermostats, and equipment. Trim-out is one of the final construction phases and requires careful coordination with the finish carpenter, tile installer, and painter to avoid damaging completed surfaces.

Seismic & Retrofit

Seismic Retrofit
The modification of an existing building to improve its earthquake resistance. Most common residential retrofits address soft-story conditions, cripple wall failures, and unbolted foundations. Single-family homes are not currently required to retrofit under LA's mandatory ordinance, but voluntary retrofits are strongly recommended for homes with these conditions, particularly on hillside lots. Costs: $15,000 to $80,000 depending on scope.
Full guide: Seismic Risk & Retrofit →
Soft-Story Condition
A building configuration where one story is significantly weaker than those above it. Most commonly, living space above a garage where large openings create a story with insufficient lateral bracing. In an earthquake, the soft story can collapse while upper floors remain intact. LA Ordinance No. 183,893 mandates retrofit of soft-story wood-frame buildings with 3+ stories and 2+ dwelling units. Single-family homes are not subject to the mandate but are recommended for voluntary retrofit.
Full guide: Seismic Risk & Retrofit →
Cripple Wall
A short wood-framed wall, typically 14 to 48 inches tall, between the foundation top and the first-floor framing. Common in pre-1960 homes. Unbraced cripple walls collapse in earthquakes, allowing the house to drop off its foundation. Bracing with structural plywood and steel hardware: $5,000 to $20,000 for the bracing portion.
Full guide: Seismic Risk & Retrofit →
Foundation Bolting
Mechanically connecting a wood-framed house to its concrete foundation using anchor bolts or retrofit hardware. Many pre-1950s homes in Los Angeles sit on their foundations without positive mechanical attachment. Foundation bolting: $3,000 to $8,000. Often performed with cripple wall bracing as a combined retrofit scope.
Full guide: Seismic Risk & Retrofit →
Ductility
The ability of a structural element to deform significantly beyond its elastic limit without catastrophic failure. Essential in seismic design because earthquakes impose deformation demands that exceed the elastic capacity of any practical structure. A ductile structure absorbs energy by flexing while maintaining its load-carrying capacity. A brittle structure (unreinforced masonry, concrete without adequate reinforcing detailing) fails suddenly when its capacity is exceeded. Modern seismic codes are fundamentally about ensuring ductility, not just strength.
Full guide: Seismic Risk & Retrofit →
Seismic Design Category
A classification assigned to every building site based on expected ground shaking severity and soil conditions. Categories range from A (lowest risk) to F (highest risk). All of Los Angeles falls into Categories D, E, or F, triggering the most stringent seismic design requirements in the country. The category determines structural detailing, connection requirements, and lateral force resistance mandated by the building code.
Full guide: Seismic Risk & Retrofit →
Non-Ductile Concrete
Reinforced concrete that lacks the reinforcing steel detailing required for ductile behavior during earthquakes: insufficient confinement ties in columns, inadequate lap splice lengths, and connection details that allow sudden failure rather than gradual yielding. Non-ductile concrete construction was standard before the 1971 San Fernando earthquake, which exposed its vulnerability. Buildings constructed between 1933 and 1971 in Los Angeles commonly contain non-ductile concrete elements that may not have been retrofitted.
Unreinforced Masonry (URM)
Masonry construction, typically brick or hollow clay tile, built without reinforcing steel. URM is the most seismically vulnerable building type because the masonry has no tensile capacity and fails suddenly in shaking. The City of Los Angeles addressed the most dangerous URM structures through its Division 88 ordinance beginning in 1981, targeting commercial and multi-family buildings. Some residential structures with URM elements, particularly chimneys and garden walls, may still contain unreinforced masonry that poses a collapse hazard in an earthquake.
Full guide: Seismic Risk & Retrofit →
Lateral Drift
The horizontal displacement of a building during an earthquake, measured as the difference in movement between the top and bottom of a story. Building codes limit allowable drift to prevent structural damage and ensure occupant safety. Excessive drift causes non-structural damage (cracked drywall, broken glass, jammed doors) even when the structure remains sound. Moment frames allow more drift than shear walls, which is why moment-frame buildings sometimes sustain more non-structural damage in moderate earthquakes even though the structural system performs as designed.

Fire Rebuild & Home Hardening

Chapter 7A (California Building Code)
The section of the California Building Code that establishes construction requirements for buildings in wildfire-prone areas, formally titled "Materials and Construction Methods for Exterior Wildfire Exposure." Chapter 7A applies to all new construction and certain rebuilds in designated Very High Fire Hazard Severity Zones and the Wildland-Urban Interface. It requires fire-resistant roofing, ember-resistant vents, enclosed eaves, non-combustible exterior cladding within specified zones, tempered or multi-pane glazing, and ignition-resistant landscaping within defensible space. These requirements directly address the ember intrusion mechanism that destroyed thousands of homes in the 2025 Palisades fires.
Full guide: Fire Rebuild →
Very High Fire Hazard Severity Zone (VHFHSZ)
A CAL FIRE and local jurisdiction designation identifying areas with the highest wildfire risk based on vegetation, topography, weather patterns, and ember exposure. Properties in VHFHSZ are subject to Chapter 7A building requirements, defensible space mandates, and enhanced insurance underwriting scrutiny. Most of the hillside communities in Los Angeles, including Pacific Palisades, Malibu, Bel Air, and the Hollywood Hills, are within VHFHSZ boundaries. The designation is mapped and available through CAL FIRE's Fire Hazard Severity Zone Viewer.
Wildland-Urban Interface (WUI)
The geographic zone where residential development meets or intermingles with undeveloped wildland vegetation. WUI properties face the highest wildfire risk because they are exposed to both wildland fire spread and structure-to-structure ignition. The Los Angeles hillside communities exist almost entirely within the WUI. Building in the WUI triggers Chapter 7A requirements and increasingly stringent insurance underwriting standards. After the 2025 fires, several major insurers withdrew from WUI zones entirely, creating the insurance availability crisis that is affecting the Palisades rebuild.
Full guide: Fire Rebuild →
Ember-Resistant Vent
A ventilation opening designed to prevent wind-driven embers from entering the building during a wildfire. Standard 1/4-inch mesh vent screens are ineffective against embers. Code-compliant ember-resistant vents use 1/8-inch or 1/16-inch mesh with baffles or intumescent materials that seal under heat exposure. Research from the Insurance Institute for Business and Home Safety (IBHS) estimates that up to 90% of homes lost in wildfires ignite from ember intrusion rather than direct flame contact. Ember-resistant vents are required under Chapter 7A and are one of the most impactful home hardening measures.
Full guide: Fire Rebuild →
Defensible Space
The area of managed vegetation and clearance surrounding a structure that reduces wildfire risk. California law requires defensible space in two zones: Zone 1 (0-30 feet from the structure) where vegetation is lean, clean, and green with no combustible materials; and Zone 2 (30-100 feet) where vegetation is reduced and spaced to prevent fire from carrying to the structure. AB 3074 (effective January 2023) added Zone 0, the immediate 0-5 foot zone around the structure, which must be an "ember-resistant zone" with non-combustible ground surfaces and no vegetation that can ignite from ember exposure.
Fire-Hardened Construction
Building assemblies and materials designed to resist ignition from wildfire exposure, particularly ember intrusion. Key elements: Class A fire-rated roof assembly, enclosed eaves and soffits (no exposed rafter tails), ember-resistant vents at all openings, non-combustible or ignition-resistant exterior cladding, tempered or dual-pane windows, non-combustible decking or decking meeting ASTM E84 Class A flame spread, and ember-resistant zone within 5 feet of the structure. Insurance carriers increasingly require fire hardening beyond code minimums as a condition of issuing or renewing coverage in VHFHSZ areas.
Full guide: Fire Rebuild →
Class A Roof Assembly
The highest fire-resistance classification for roof covering materials, indicating effective resistance against severe fire test exposure including burning brands (embers), intermittent flame, and radiant heat. Class A roofs are required in VHFHSZ under Chapter 7A. Common Class A materials include concrete tile, clay tile, metal roofing (standing seam), and asphalt shingles rated Class A. The roof assembly includes not just the surface material but the underlayment and deck beneath it, which must also meet fire-resistance requirements.
Debris Flow
A fast-moving mass of water-saturated rock, soil, and organic material that flows downhill under gravity, typically triggered by heavy rainfall on slopes denuded of vegetation by wildfire. Debris flows are among the most dangerous post-fire hazards in hillside communities. The January 2018 Montecito debris flow, triggered by rain on the Thomas Fire burn scar, killed 23 people and destroyed over 100 homes. The PGRAZ designations created after the 2025 Palisades fires specifically address debris flow risk for properties downslope of fire-denuded hillsides.
Full guide: PGRAZ Fire Rebuilds →
110% Rule (Fire Rebuild Permitting)
Under Mayor Bass's Executive Order 1, fire rebuilds within 110% of the original building footprint and height qualify for expedited plan check, potentially 30 days instead of the standard 6-18 months. The 110% limit applies to footprint and height only and does not limit total square footage, basements, or new ADUs, which are exempt from the calculation. Projects exceeding 110% follow standard permitting. Building permits must be obtained by January 13, 2032, with construction completed within 3 years of permit issuance.
Full guide: Fire Rebuild →
120% Rule (Proposition 13 Property Tax)
A separate threshold from the 110% permitting rule. Under Proposition 13, if the full cash value of the rebuilt home stays below 120% of the destroyed home's value, the existing Prop 13 base year value is maintained, avoiding a property tax reassessment. A project can qualify under 110% for permitting while exceeding 120% for tax purposes, or vice versa. Both should be evaluated during pre-construction.
Full guide: Fire Rebuild →
Additional Living Expense (ALE)
An insurance coverage that pays for temporary housing and increased living costs when the insured's home is uninhabitable due to a covered loss. ALE coverage has a dollar limit and a time limit, typically 24 months. For custom hillside rebuilds in the Palisades that take 2.5 to 3.5 years, there is often a gap between ALE expiration and project completion. Monthly ALE costs in the Palisades market can exceed $15,000. The ADU-first strategy, building an 800-1,200 SF accessory dwelling unit before the main house, can provide on-site housing that preserves ALE benefits.
Full guide: Fire Rebuild →

Insurance & Financial Protection

Builder's Risk Insurance
A property insurance policy covering the structure under construction, including materials and equipment on site or in transit, against fire, weather, theft, vandalism, and other covered perils. Coverage should equal the full replacement value of the work in place and be maintained from construction start through substantial completion. On a $5 million project, premiums typically run $15,000 to $30,000. Distinct from general liability insurance (bodily injury/property damage to third parties) and the homeowner's existing property insurance (which typically excludes construction activity).
Full guide: Insurance & Construction →
General Liability Insurance
Insurance covering the contractor's liability for bodily injury and property damage to third parties caused by construction operations. Minimum recommended limits for residential projects over $1 million: $2 million per occurrence. The owner should be named as an additional insured on the contractor's policy, which extends coverage to the owner for claims arising from the contractor's work. Verify that the certificate of insurance is current, that limits are adequate, and that the additional insured endorsement is in place before construction begins.
Workers' Compensation Insurance
Insurance that covers medical expenses and lost wages for workers injured on the job. California law requires all employers, including construction contractors, to carry workers' compensation coverage. If a contractor does not carry workers' comp and a worker is injured on your property, you as the property owner can be held liable. Verify the contractor's workers' compensation certificate is current before any work begins, and verify that all subcontractors carry their own coverage.
Additional Insured
A person or entity added to someone else's insurance policy who receives coverage under that policy for claims arising from the named insured's operations. On a construction project, the owner is typically named as an additional insured on both the contractor's general liability policy and the subcontractors' policies. This means that if a third party is injured on the project and sues the owner, the contractor's insurance responds. The additional insured endorsement should be verified on every certificate of insurance before construction begins.
Certificate of Insurance (COI)
A document issued by an insurance company confirming that a specific insurance policy is in force, listing the coverage types, policy limits, effective dates, and any additional insured endorsements. The owner should collect COIs from the general contractor or CM and from every subcontractor before they begin work on the project. COIs should be verified for current dates, adequate limits, and the owner's additional insured status. Expired or inadequate COIs are a common risk that should be caught during pre-construction, not discovered after an incident.
Replacement Cost Value (RCV)
The amount it would cost to replace a damaged or destroyed property with materials of like kind and quality at current prices, without deduction for depreciation. Insurance policies that pay replacement cost provide more coverage than policies that pay actual cash value. For fire rebuilds in the Palisades, the gap between insurance replacement cost estimates and actual reconstruction costs is frequently $500,000 to $1,500,000 because insurance models underestimate hillside construction costs.
Full guide: Insurance & Construction →
Actual Cash Value (ACV)
The replacement cost of property minus depreciation. An ACV policy pays what the damaged property was worth at the time of the loss, not what it costs to replace it. For a 20-year-old roof destroyed by fire, ACV pays the depreciated value of a 20-year-old roof, not the cost of a new roof. ACV policies provide significantly less coverage than replacement cost policies and can leave homeowners substantially underinsured for rebuilding.
Code Upgrade Coverage (Ordinance and Law)
An insurance coverage endorsement that pays for the additional cost of rebuilding to current building code when the original structure was built under older, less restrictive codes. This coverage is critical for older homes that will be rebuilt to current California Building Code, Title 24 energy code, and Chapter 7A fire-hardening requirements. Without this coverage, the homeowner bears the full cost of code-required upgrades that the original structure did not include. Standard coverage limits are typically 10-25% of the dwelling coverage amount.
Public Adjuster
A licensed claims professional who represents the policyholder, not the insurance company, in negotiating an insurance claim. Public adjusters typically work on a contingency fee of 10-15% of the claim settlement. On complex fire rebuild claims where the gap between insurance coverage and actual rebuild cost is significant, a public adjuster can advocate for a higher settlement. The quality of the underlying cost documentation, including competitive subcontractor pricing and open-book cost breakdowns, is the foundation of any successful claim negotiation regardless of whether a public adjuster is involved.
Full guide: Insurance & Construction →
Proof of Loss
A sworn statement submitted by the policyholder to the insurance company documenting the items lost or damaged, their value, and the circumstances of the loss. Insurance carriers require proof of loss as part of the claims process. On fire rebuild claims, the proof of loss must include detailed documentation of the destroyed structure's characteristics, contents, and replacement cost. Professional cost documentation prepared by a construction manager or qualified estimator strengthens the proof of loss because it is based on competitive market pricing, not a single contractor's estimate.
Dwelling Coverage
The portion of a homeowner's insurance policy that covers the cost to repair or rebuild the physical structure. The dwelling coverage limit is the maximum the insurer will pay for the structure itself, excluding contents, landscaping, and additional living expenses. Most fire victims in the Palisades are discovering that their dwelling coverage limits were based on replacement cost estimates that significantly underestimate actual hillside construction costs. Understanding this gap early, before committing to a design scope, allows the rebuild to be scoped to match available resources.
Full guide: Insurance & Construction →

Permitting & Regulatory

LADBS (Los Angeles Department of Building and Safety)
The agency responsible for building code review, permit issuance, and construction inspection in the City of Los Angeles. On complex projects, LADBS review involves multiple divisions including Plan Check, the Grading Division, and Structural Plan Check. LADBS is one of multiple agencies involved in a residential permit; others include Planning, Bureau of Engineering, LAFD, LADWP, and potentially the California Coastal Commission.
Full guide: Los Angeles Permitting →
Baseline Hillside Ordinance (BHO)
City of Los Angeles Ordinance No. 181,624 establishing development standards for single-family homes in the mapped Hillside Area. Regulates FAR through a slope-band formula (0.50 for 0-15% slope down to zero for slopes exceeding 100%), height limits, setbacks, and Maximum Grading Quantities. On steep lots, the BHO's grading limits can dictate the foundation system before the structural engineer starts designing. Check ZIMAS to verify your property's status.
Full guide: Hillside Construction →  |  Grading Limits →
Slope Band (BHO)
The BHO divides each lot into bands based on the slope gradient of the terrain: 0-15%, 15-30%, 30-45%, 45-60%, 60-100%, and over 100%. Each band has a different Floor Area Ratio and different grading allowances. The effective buildable area of a hillside lot is determined by calculating the area within each slope band and applying the corresponding FAR. A lot that appears large on a flat map may have very limited buildable area once the slope bands are analyzed. A slope band analysis prepared by a licensed surveyor is required as part of the permit application.
Full guide: Grading Limits →
Baseline Mansionization Ordinance (BMO)
City of LA Ordinance No. 179,883 (2008, amended 2017) limiting maximum floor area of single-family homes in R1 zones based on lot size. On a standard 7,500 SF R1 lot, the BMO yields approximately 3,375 SF of residential floor area. An existing home exceeding current BMO limits is legally nonconforming, and renovation preserves that square footage while demolition resets entitlements to the smaller current limit.
Full guide: Tear Down or Renovate →  |  Zoning →
PGRAZ (Palisades Geohazard Risk Assessment Zones)
Geohazard designations established by LADBS after the January 2025 Palisades fires identifying areas with elevated geological risk. Orange zones: sites on or adjacent to steep slopes or potential landslide areas. Yellow zones: sites at the bottom of steep slopes prone to debris flow. Properties in PGRAZ zones require enhanced geotechnical investigation for any construction, adding $15,000 to $50,000+ in investigation costs. The designation does not make property unbuildable but changes engineering and permitting requirements significantly.
Full guide: PGRAZ Fire Rebuilds →
Coastal Development Permit (CDP)
A permit required under the California Coastal Act for new construction, major remodels, and most exterior work within the Coastal Zone. Evaluates impact on coastal resources, public access, visual character, and environmentally sensitive habitat areas. In Malibu, nearly all exterior construction requires a CDP with potential public hearing, adding 6-18 months. For fire rebuilds within 110% of original footprint, streamlined pathways bypass standard CDP process.
Full guide: Coastal Construction in Malibu →
ZIMAS (Zone Information and Map Access System)
The City of Los Angeles online database providing zoning, land use, and regulatory information for every parcel. Shows zoning designation, hillside area status, fire zone, fault zone, liquefaction zone, overlay districts, specific plan areas, and pending cases. The first stop in any lot evaluation. Publicly accessible at zimas.lacity.org.
Full guide: Lot Due Diligence →
Floor Area Ratio (FAR)
The ratio of building floor area to lot area. A FAR of 0.45 on a 10,000 SF lot means 4,500 SF maximum residential floor area. The primary density control in LA residential zoning, calculated differently under the BMO (flat lots) and BHO (hillside lots with slope-band formula).
Full guide: Zoning →
Residential Floor Area (RFA)
The specific measurement of floor area used for zoning compliance in the City of Los Angeles, defined under LAMC Section 12.03. RFA includes all enclosed floor area measured from exterior walls, with specific inclusions and exclusions defined in the code. Understanding what counts toward RFA and what does not (certain garage area, covered patios under specific conditions) is critical for maximizing buildable area within the FAR limits imposed by the BMO or BHO.
Full guide: Zoning →
Plan Check
The process by which LADBS reviews submitted construction documents for compliance with the California Building Code and local amendments. Plan check can be performed by LADBS staff or by approved third-party plan check firms. Complex hillside projects typically require 2-4 correction cycles before approval. Each correction cycle adds 4-8 weeks. Submitting complete, well-coordinated plans and addressing all corrections completely on first resubmittal are the most effective ways to minimize plan check duration.
Full guide: Los Angeles Permitting →
Correction Cycle
When LADBS or a third-party plan checker identifies deficiencies in the submitted construction documents, they issue a correction sheet listing the items that must be addressed before the plans can be approved. The design team revises the documents and resubmits. Each correction cycle adds 4-8 weeks to the permitting timeline. On complex hillside projects, 2-4 correction cycles are typical. The number of corrections is directly related to the completeness and coordination quality of the original submission.
Third-Party Plan Check
An alternative to LADBS in-house plan check where an approved private firm reviews the construction documents for code compliance. Third-party plan check can be faster than LADBS review when the department has significant backlog. The plans are still submitted to LADBS for permit issuance, but the technical review has been completed by the third-party firm, streamlining the LADBS processing time.
Hillside Construction Regulation (HCR)
A Supplemental Use District (Ordinance No. 184,827) layered on top of the BHO in specific hillside areas including Bel Air-Beverly Crest. While the BHO governs what you can build, the HCR governs how you can build it: construction hours limited to Monday-Friday 8 AM to 6 PM, hauling restricted to 9 AM to 3 PM Monday-Friday only, maximum 6,000 cubic yards cumulative grading, off-site truck staging, and haul route approval. The 6-hour daily hauling window is often the primary schedule constraint on projects in HCR districts.
Full guide: Hillside Construction →
Grading Permit
A permit required for any excavation, fill, or earth movement in an LADBS-designated Hillside Grading Area. Requires an approved geotechnical report, haul route approval, and building permit coordination. On hillside projects, the grading permit is often on the critical path because it depends on multiple agency timelines.
Full guide: Grading Limits →
Certificate of Occupancy (C of O)
The document issued by LADBS certifying that a completed building complies with approved plans and applicable codes and is safe for occupancy. Required before the owner can legally occupy the building and before lenders release final construction loan draws. Can take 2-4 weeks after physical completion due to agency scheduling.
Nonconforming Structure (Legal Nonconforming)
A building legally constructed under codes in effect at the time but not complying with current zoning. Many LA homes exceed current zoning limits due to the BMO and BHO reducing allowable floor area. Under LAMC Section 12.23, a nonconforming building may be maintained, repaired, or altered provided at least 50% of the perimeter length of nonconforming exterior walls is retained. Demolition resets entitlements to current limits.
Full guide: Tear Down or Renovate →
Conditional Use Permit (CUP)
A discretionary approval allowing a land use that is not permitted by right in the applicable zoning but may be approved subject to conditions. CUPs require a public hearing before the Zoning Administrator or Area Planning Commission. On residential projects, CUPs are sometimes required for uses like home offices, short-term rentals, or accessory structures that exceed specific thresholds. The discretionary review process adds 6-12+ months to the permitting timeline.
Variance
A discretionary approval allowing a deviation from a specific zoning requirement (setback, height, lot coverage) based on a demonstrated hardship unique to the property. Variances require findings that strict application of the zoning code would deprive the property of privileges enjoyed by other properties in the same zone, and that the variance will not be materially detrimental to adjacent properties. Variances require a Zoning Administrator hearing and add significant time to the permitting process.
Zoning Administrator Determination (ZAD)
A ruling by the LADBS or Planning Department Zoning Administrator on a specific zoning question, such as whether a proposed use or configuration complies with the applicable zoning code. ZADs are sometimes required to resolve ambiguities in how the code applies to a specific property or project. They involve a public hearing process and add time to permitting but are sometimes necessary to confirm the project's zoning compliance before plan check proceeds.
HPOZ (Historic Preservation Overlay Zone)
A zoning overlay that establishes design review requirements for properties within designated historic neighborhoods. Exterior modifications to structures within an HPOZ require review and approval by the HPOZ Board, which evaluates compatibility with the historic character of the neighborhood. HPOZ review adds an additional layer of discretionary approval that can affect project design, materials, and timeline.
CEQA (California Environmental Quality Act)
A state law requiring public agencies to evaluate and disclose the environmental impacts of proposed projects before approving them. Most single-family residential projects are categorically exempt from CEQA, but projects requiring discretionary approvals (variances, CUPs), projects in sensitive environmental areas, or projects exceeding certain thresholds may trigger CEQA review. For fire rebuilds within 110% of the original footprint, Executive Order 1 suspends CEQA requirements.
ESHA (Environmentally Sensitive Habitat Area)
A designation under the California Coastal Act identifying areas of rare, sensitive, or especially valuable habitat. Development within or adjacent to ESHA is subject to strict limitations under the Local Coastal Program. In Malibu, ESHA designations are common and can significantly constrain the building envelope, require setbacks of 100 feet or more from the habitat boundary, and add months to the Coastal Development Permit process.
Full guide: Coastal Construction in Malibu →
Local Coastal Program (LCP)
A set of policies and ordinances adopted by a local government and certified by the California Coastal Commission to govern development within the Coastal Zone. The Malibu LCP governs development standards including height limits (18-28 feet depending on zone), lot coverage, setbacks, impervious surface limits, and ESHA protection. In certified LCP areas, the local government issues Coastal Development Permits rather than the Coastal Commission directly, although the Commission retains appeal authority.
Full guide: Coastal Construction in Malibu →
Easement
A legal right granting someone other than the property owner a specific use of the property. Common easements on residential properties include utility easements (allowing utility companies to access lines running through the property), drainage easements (requiring that natural drainage patterns be maintained), and access easements (granting a neighbor the right to cross your property). Easements are recorded in the property's title and appear on the preliminary title report. Building within an easement is typically prohibited or restricted, which can reduce the buildable area of the lot.
Full guide: Lot Due Diligence →
Lot Tie
A recorded covenant that links two or more adjacent parcels together as a single development site for zoning purposes. Lot ties are commonly used on hillside properties where a buildable project requires more area than a single lot provides, or where existing improvements span multiple legal parcels. Once recorded, the tied lots must be developed together and cannot be separately sold or developed without removing the covenant, which typically requires City approval.
Accessory Dwelling Unit (ADU)
A secondary residential unit on a single-family lot, permitted under California state law with streamlined approval that bypasses many local zoning restrictions. ADUs can be up to 1,200 SF (or 1,000 SF for detached units on many lots) and can include a full kitchen and bathroom. The key distinction is whether the structure includes a kitchen: if it does, it is an ADU under state law regardless of what you call it. On fire rebuild projects, ADUs are exempt from the 110% calculation and can be built as a first phase to provide on-site housing while the main house is under construction.
Full guide: Zoning →
CSLB (Contractors State License Board)
The California state agency that licenses and regulates contractors. Every contractor performing work valued at $500 or more must hold a valid license. The CSLB database at cslb.ca.gov allows anyone to verify license status, classification, bond information, and complaint history. A B classification (General Building Contractor) authorizes construction or renovation of buildings. Before hiring any contractor, verify their license is current, active, and in good standing.
ePlanLA
The City of Los Angeles electronic plan submittal and tracking system. ePlanLA allows architects and applicants to submit construction documents electronically rather than in paper format, track plan check status online, receive correction comments electronically, and resubmit revised documents digitally. Using ePlanLA typically reduces overall permitting timelines compared to paper submittals.
Full guide: Los Angeles Permitting →

Environmental & Hazmat

Asbestos-Containing Material (ACM)
Any material containing more than 1% asbestos. Common in pre-1978 buildings in insulation, floor tiles, roofing, joint compound, popcorn ceilings, pipe wrap, and exterior stucco. California and federal regulations require a hazardous materials survey before any renovation or demolition that will disturb these materials. Asbestos abatement must be performed by a licensed contractor and typically costs $10,000 to $75,000 on a residential renovation depending on quantity and type.
Full guide: Environmental Compliance →
Lead-Based Paint (LBP)
Paint containing lead, common in homes built before 1978 when the federal government banned lead-based paint for residential use. Disturbing lead paint during renovation creates toxic dust and debris that must be handled under specific EPA and Cal/OSHA protocols. All contractors performing work that disturbs lead paint in pre-1978 homes must be EPA RRP (Renovation, Repair, and Painting) certified. Lead paint abatement costs vary widely based on scope and can add significant cost to renovations of older homes.
Full guide: Environmental Compliance →
AQMD (South Coast Air Quality Management District)
The regional agency responsible for air quality regulation in the South Coast Air Basin, which includes Los Angeles County. AQMD requires notification and specific handling protocols for demolition of any structure, with additional requirements for structures containing asbestos or other regulated materials. AQMD notification must be filed before demolition begins. Failure to comply can result in significant fines and stop-work orders.
Full guide: Environmental Compliance →
Abatement (Environmental)
The removal, encapsulation, or enclosure of hazardous materials such as asbestos and lead paint by a licensed abatement contractor following regulatory protocols. Abatement must be completed before renovation or demolition work can disturb the hazardous material. The abatement contractor must hold specific certifications, follow containment and disposal procedures prescribed by AQMD and Cal/OSHA, and provide clearance testing documentation confirming the work area is safe for subsequent construction activity.
Phase I Environmental Site Assessment
A non-intrusive investigation that evaluates a property's environmental history through records review, site inspection, and interviews to identify recognized environmental conditions that could indicate contamination. Phase I assessments are standard in commercial real estate transactions and are sometimes performed on residential properties with previous industrial use, known chemical storage, or proximity to contaminated sites. If a Phase I identifies potential contamination, a Phase II assessment (involving soil and groundwater sampling) is performed to confirm and characterize the condition.
Stormwater Pollution Prevention Plan (SWPPP)
A plan required under the National Pollutant Discharge Elimination System (NPDES) for construction projects that disturb one or more acres of soil. The SWPPP identifies potential pollutant sources, describes Best Management Practices (BMPs) to prevent stormwater contamination during construction, and establishes monitoring and reporting requirements. On hillside sites where grading and excavation expose large areas of soil, SWPPP compliance is critical to prevent sediment-laden runoff from reaching storm drains and waterways.
BMP (Best Management Practice)
Erosion control and pollution prevention measures implemented on construction sites to comply with stormwater regulations. Common BMPs include silt fences along the downhill perimeter of disturbed areas, fiber rolls (straw wattles) across slopes to slow and filter runoff, stabilized construction entrances to prevent trucks from tracking sediment onto public streets, sediment basins or traps at drainage collection points, and dust control through watering. BMPs must be installed before grading begins and maintained throughout construction.
Methane Mitigation
Construction measures required in areas where methane gas is present in the soil at concentrations that could accumulate to dangerous levels within a building. Parts of Los Angeles, particularly areas near the La Brea Tar Pits, former oil fields, and landfills, are within designated methane zones or methane buffer zones. Buildings in these areas require sub-slab ventilation systems, membrane barriers, and gas detection systems. The Los Angeles Methane Mitigation Ordinance (LAMC Division 71) defines the design and testing requirements based on the methane concentration level detected on the site.

Site Work & Construction Logistics

Crane Mobilization
The process of transporting, assembling, and setting up a crane on a construction site. On hillside projects in Los Angeles, crane selection is constrained by site access, available setup area, and the reach required to service the building footprint. Mobile cranes (truck-mounted or crawler-mounted) are the most common on residential projects. Tower cranes are used on larger projects where the extended duration justifies the higher mobilization cost and where the building footprint is large enough to require a crane that remains in a fixed position. Crane mobilization on a hillside project can cost $20,000 to $80,000+ depending on the crane type and the complexity of the setup.
Tower Crane
A fixed crane erected on site that provides lifting capability from a tall mast with a horizontal boom (jib). Tower cranes are used on larger residential projects where the extended construction duration and the size of the building footprint justify the significant mobilization cost ($50,000-$150,000+) and monthly rental. Tower cranes require a foundation (typically a concrete pad or the building's own foundation), permits from LADBS and OSHA documentation, and a certified operator for the duration they are on site.
Access Road
A temporary or permanent road constructed on a hillside site to allow construction equipment and material delivery trucks to reach the building pad. On steep sites, the access road may need to be cut into the hillside with switchbacks, requiring grading permits and geotechnical engineering. Access road construction is often one of the first construction activities on a hillside project and can represent a significant early cost ($50,000-$200,000+) that must be completed before any other work can proceed.
Staging Area
A designated space on or adjacent to the construction site used for storing materials, parking equipment, and assembling components before installation. On hillside sites with constrained access, the staging area is often the most limited resource on the project. Material deliveries must be scheduled precisely because there is no room to stockpile, and equipment that cannot be stored on site must be mobilized and demobilized for each use, adding cost and time. Staging constraints directly affect the construction schedule and are a primary reason hillside projects take longer than comparable flat-lot projects.
Skid Steer
A compact, maneuverable piece of construction equipment used for grading, material handling, demolition, and general site work on constrained sites. Skid steers are the workhorse of hillside residential construction because they can operate in spaces too tight for conventional excavators and can be transported on a standard flatbed trailer. BCG maintains its own skid steers for site work on hillside projects where equipment access is limited.
Temporary Power
Electrical service provided to a construction site before the permanent electrical system is installed. Temporary power is typically provided through a temporary service panel mounted on a pole or the building frame, connected to the utility grid with a temporary service drop from LADWP. Obtaining temporary power requires an electrical permit and LADWP coordination, which can take 4-8 weeks. On sites without nearby utility infrastructure, temporary power may require a generator, adding fuel costs and noise management to the project.
Erosion Control
Measures implemented during construction to prevent soil from being carried off the site by water or wind. Required on all grading projects and critical on hillside sites where exposed slopes can generate significant runoff during rain events. Erosion control measures include silt fences, fiber rolls, hydroseeding, erosion control blankets, geotextile fabric, and temporary vegetation. On post-fire hillside sites where vegetation has been destroyed, erosion control is particularly important during the first 3-5 rainy seasons until vegetation is reestablished.
Full guide: Hillside Construction →

Construction Operations & Process

Change Order
A written modification to the construction contract adjusting scope, contract sum, contract time, or a combination. Under AIA A201, requires agreement of owner, contractor, and architect. In CMAR, the CM prices the change and presents cost and schedule impact before work proceeds. Owner-directed changes draw from owner contingency and adjust the GMP. Changes due to unforeseen conditions draw from construction contingency.
Full guide: Construction Contracts →
Substantial Completion
The stage when work is sufficiently complete for the owner to use or occupy the building. Determined by the architect, not the contractor. Triggers warranty period, shifts insurance and security responsibility to the owner, and initiates the final payment and punch list process. Distinct from final completion, which occurs after all punch list items, final inspections, and closeout documentation are complete.
Punch List
A documented list of incomplete or deficient items identified during the substantial completion inspection. On complex residential projects, 100 to 300+ items ranging from cosmetic touch-ups to functional adjustments. Punch list completion is a contractual obligation, and retention is not released until all items are satisfactorily resolved.
OAC Meeting (Owner-Architect-Contractor)
A regularly scheduled meeting, typically weekly or biweekly, where the owner, architect, and CM review project status, discuss design issues, make decisions, and coordinate upcoming work. The primary governance mechanism for a construction project. The CM prepares agendas, distributes minutes, and tracks action items to closure.
Pay Application (Progress Payment)
A monthly payment request from the contractor based on percentage of work completed. In CMAR with open-book accounting, includes a detailed schedule of values showing each line item's budget, previous billing, current billing, remaining balance, and percentage complete. The architect reviews and certifies each pay application before the owner releases payment.
Long-Lead Items
Materials or systems requiring extended procurement timelines, typically 3 to 6 months or more. Common examples: European windows and doors, custom stone and tile, specialty hardware, custom millwork, and certain mechanical equipment. Must be identified and ordered during design, not after the building is framed and waiting. Failure to procure long-lead items early is one of the most preventable causes of schedule delays.
Full guide: Construction Timeline →
Construction Administration (CA)
The architect's contractual responsibilities during construction as defined in AIA B101: reviewing submittals, visiting the site, certifying pay applications, evaluating change orders, interpreting documents, and determining completion. CA is not construction supervision. The architect observes whether work conforms to the design; the CM manages trades, schedule, budget, and day-to-day execution. Both roles are essential in CMAR.
Full guide: The Architect's Role →
Self-Performance
Work performed by the CM's or GC's own labor force rather than by subcontractors. Self-performance capabilities can include demolition, grading, trenching, site logistics, access road construction, crane operations, framing, and carpentry. Provides direct schedule control over critical-path activities, eliminates subcontractor markup, and ensures qualified personnel are on site for tasks requiring daily adaptation. Specialty trades are typically subcontracted through competitive bidding.
Means and Methods
The specific techniques, equipment, procedures, and construction sequences the contractor uses to build the project. Under AIA A201, means and methods are the contractor's responsibility, not the architect's or owner's. The architect specifies what is to be built; the contractor determines how. On hillside projects, means and methods decisions, including crane type, shoring sequence, excavation approach, and delivery logistics, have significant cost implications.
Daily Log (Field Report)
A written record prepared by the site superintendent or project manager documenting each day's construction activity: weather conditions, trades on site and their headcount, work performed, materials received, equipment used, inspections conducted, visitors to the site, any safety incidents, and any delays or unusual conditions encountered. Daily logs are the contemporaneous record of what happened on the project and are critical documentation in the event of disputes, claims, or delay analysis. In a CMAR engagement, daily logs are part of the standard project documentation.
Shop Drawing
A detailed fabrication drawing prepared by a manufacturer, subcontractor, or fabricator showing the exact dimensions, materials, connections, and installation details of a specific component or assembly. Shop drawings translate the architect's design intent into fabrication instructions. Common shop drawing packages include structural steel connections, custom millwork, curtain wall systems, mechanical ductwork layouts, and specialty metalwork. The architect reviews shop drawings for conformance with the design intent before fabrication proceeds.
As-Built Drawings
Revised construction drawings that document the project as it was actually built, including all field changes, RFI resolutions, and deviations from the original construction documents. As-builts are prepared by the contractor during construction by marking up a set of drawings with actual conditions as each system is installed. They are delivered to the owner at project closeout and are essential for future maintenance, renovation, and repair, particularly for concealed systems like underground utilities, MEP routing, and structural elements that will be hidden behind finishes.
Warranty Period
The period following substantial completion during which the contractor is obligated to correct defective work at no cost to the owner. Under AIA A201, the standard warranty period is one year from the date of substantial completion. Individual product and system warranties from manufacturers and subcontractors may extend longer. Roofing, waterproofing, and window systems often carry 10-20 year manufacturer warranties in addition to the contractor's one-year obligation. Warranty documentation and contact information are part of the closeout deliverables.
Final Completion
The point at which all work under the contract, including all punch list items, has been completed, all final inspections have been passed, the Certificate of Occupancy has been issued, and all closeout documentation has been delivered. Final completion triggers the release of retention and the final payment to the contractor. It is distinct from substantial completion, which occurs earlier when the building is usable but minor items remain.
Commissioning
A systematic process of testing and verifying that building systems, particularly HVAC, lighting controls, and automation, perform according to the design intent and the owner's operational requirements. Commissioning goes beyond standard startup and testing by evaluating how systems perform together under various conditions. On high-end residential projects with complex HVAC, automation, lighting, and security systems, commissioning ensures that the integrated systems work as intended before the owner takes occupancy.

Finishes & Interior

Millwork (Custom Cabinetry)
Custom-fabricated wood or wood-composite components built in a shop and installed on site: cabinetry, built-in bookshelves, paneling, wainscoting, door and window casings, crown molding, and specialty architectural elements. Millwork is typically the single largest finish trade scope on a custom residential project, ranging from $200,000 to $800,000+ depending on the extent of custom work and the materials specified. Millwork requires detailed shop drawings, architect approval, and fabrication lead times of 8-16 weeks. It is one of the most common long-lead items on residential projects.
Rough Carpentry vs. Finish Carpentry
Rough carpentry is the structural wood framing and blocking that forms the building skeleton: wall framing, floor framing, roof framing, shear wall installation, blocking for fixtures and cabinetry, and structural hardware installation. Finish carpentry is the visible wood work installed after the surfaces are complete: door and window casing, baseboard, crown molding, stair railings, built-in shelving, and trim. On a CMAR project, rough carpentry is often self-performed by the CM's framing crew for schedule control, while finish carpentry is typically a specialty subcontractor scope.
Thin-Set vs. Mud-Set (Tile Installation)
The two primary methods for installing tile. Thin-set uses a thin layer of cement-based adhesive to bond tile directly to a prepared substrate (cement board, waterproof membrane, or concrete). Mud-set (also called mortar bed or thick-set) uses a thick layer of sand-cement mortar to create a perfectly level substrate before the tile is set. Mud-set allows more flexibility in creating slopes for drainage (critical in showers and wet areas), accommodates substrate irregularities, and is preferred for large-format stone and tile. Mud-set is more labor-intensive and expensive but produces a superior result on high-end residential projects.
Natural Stone (Slab vs. Tile)
Stone materials used for countertops, flooring, wall cladding, and exterior hardscape. Slab stone (marble, quartzite, granite, onyx) is cut from large blocks and fabricated into countertops and feature walls, with material costs ranging from $30 to $300+ per square foot depending on rarity and origin. Tile stone is cut into standard dimensions for flooring and wall applications. Natural stone selection is one of the most significant cost variables in interior finishes and is a common long-lead item, particularly for imported materials where the specific slab must be selected at the quarry or fabricator.
Hardwood Flooring (Engineered vs. Solid)
Solid hardwood flooring is milled from a single piece of wood, typically 3/4 inch thick, and can be sanded and refinished multiple times over its life. Engineered hardwood is a dimensional plywood core with a hardwood veneer face, typically 1/8 to 1/4 inch thick. Engineered hardwood is more dimensionally stable (less expansion and contraction with humidity changes), can be installed over concrete slabs with radiant heating, and is available in wider plank widths. On high-end residential projects, both solid and engineered hardwood are common, with the choice driven by the installation substrate, the desired plank width, and whether the floor will be over radiant heating.
Plaster (Venetian Plaster, Lime Plaster)
Hand-applied wall and ceiling finish materials that create textured, luminous surfaces distinct from standard drywall and paint. Venetian plaster (also called polished plaster) uses multiple thin layers of lime-based or synthetic plaster burnished with a trowel to create a smooth, stone-like surface with depth and variation. Lime plaster is a traditional material that is breathable, naturally antimicrobial, and develops a patina over time. Plaster finishes are a specialty trade scope, significantly more expensive than paint ($15-$50+ per square foot vs. $3-$6 for paint), and require skilled applicators with lead times for availability.

If you are navigating a complex construction decision and want to understand what the terminology means for your specific project, we are happy to talk.

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The definitions on this page reflect how construction terminology applies in practice on complex residential projects in Los Angeles. Definitions are written from direct project experience and are not intended as legal or regulatory interpretations. Cost ranges, timelines, and regulatory references reflect current conditions and may vary based on project-specific circumstances. Consult qualified professionals for project-specific guidance.

Benson Construction Group serves Los Angeles County including Pacific Palisades, Bel Air, Beverly Hills, Brentwood, Malibu, Hollywood Hills, Encino, Tarzana, Palos Verdes, and the greater Westside.