Residential Zoning

Every construction project in Los Angeles starts with the same question: what can I actually build on this lot? Not what you want to build. Not what the architect envisions. What the zoning code currently allows - the maximum square footage, the height, the setbacks, the lot coverage - before you spend a dollar on design.

This is the single most important piece of information in any residential project, and it is the piece most frequently misunderstood. We have seen owners purchase lots assuming they could build a 5,000 square foot home, only to discover that zoning limits them to 3,200. We have seen architects design homes that exceed the allowable Residential Floor Area by hundreds of square feet, requiring months of redesign. We have seen teardown decisions made without anyone checking whether the replacement home could actually be larger than the one being demolished.

The City of Los Angeles zoning code is not simple. It is layered. A single property can be subject to its base zone, a height district, a specific plan, a neighborhood overlay, hillside regulations, coastal zone restrictions, and a Historic Preservation Overlay Zone - all simultaneously. Understanding what applies to your lot, and how those layers interact, is the difference between a project that moves through permitting efficiently and one that stalls before it starts.

This guide covers the zoning framework that governs single-family residential construction in Los Angeles. It is written for owners evaluating a lot purchase, considering a teardown, or planning an addition or new home in Pacific Palisades, Bel Air, Malibu, Beverly Hills, Brentwood, and the greater Westside. It is also written for the architects and engineers we work with who need a single reference that explains how these rules work together in practice, not just in theory.

Last updated: February 2026

1. HOW TO READ A ZONING DESIGNATION

Every property in the City of Los Angeles has a zoning string - a combination of letters and numbers that encodes the rules governing what can be built there. A typical residential designation might read R1-1 or RE15-1-H. Understanding how to decode that string is the first step toward understanding your lot.

The string has several components. The first element is the zone classification, which defines the use. For single-family residential properties, the most common zones are R1 (One-Family), RS (Suburban), RE (Residential Estate, with variations like RE9, RE11, RE15, RE20, and RE40 based on minimum lot size), and RA (Suburban Agricultural). The number following the zone classification is the height district, which governs maximum floor area ratio and, in some cases, height. Most residential properties are in Height District 1. Some properties carry additional suffixes or prefixes that indicate supplemental use districts, "D" limitations, or "Q" qualified conditions, each adding another regulatory layer.

For example, a property zoned R1-1 is in the R1 One-Family zone in Height District 1 with no additional overlays embedded in the zoning string. A property zoned R1-1-HPOZ is the same base zone but is also within a Historic Preservation Overlay Zone. A property zoned RE15-1-H is in the Residential Estate zone with a 15,000 square foot minimum lot size, in Height District 1, and located in a designated Hillside Area.

2. RESIDENTIAL FLOOR AREA: THE NUMBER THAT MATTERS MOST

For single-family residential properties in Los Angeles, the metric that controls the size of your home is Residential Floor Area (RFA). This is not the same as the total square footage your real estate agent quotes. RFA is a defined term in the LAMC (Section 12.03) that includes specific areas and excludes others, and the calculation determines the maximum allowable building size on your lot.

RFA includes the total area within the exterior walls of all buildings and accessory buildings on the lot. It counts every floor, including the area of the garage (with limited exemptions), attics with ceiling heights above seven feet, and any floor area where the ceiling exceeds 14 feet (which counts double under current rules, with a limited exemption for the first 100 square feet). Stairwells and elevator shafts are counted only once regardless of how many floors they serve.

Certain areas are excluded from the RFA calculation. For properties not in the Hillside Area or Coastal Zone, the first 200 square feet per required covered parking space is exempt (so typically 400 square feet for a two-car garage). Detached accessory buildings of 200 square feet or less are exempt, up to a combined maximum. Basements are exempt if the upper surface of the floor above does not exceed two feet above grade at any point. Porches, patios, and breezeways with a lattice roof that are open on at least two sides may be exempt.

3. FAR ON FLAT LOTS: THE BASELINE MANSIONIZATION ORDINANCE

For single-family properties outside of a Hillside Area or Coastal Zone, the maximum RFA is governed by what is commonly known as the Baseline Mansionization Ordinance (BMO). Originally adopted in 2008 as Ordinance No. 179,883 and significantly amended in 2017 by Ordinance No. 184,802, the BMO establishes the base floor area ratio for residential zones across the city.

The history matters because it explains why many existing homes on the Westside are larger than what current zoning would allow. Before the BMO, the R1 zone permitted a floor area ratio that could allow homes far exceeding what the neighborhood was designed to accommodate. The original BMO set the ratio at 0.50 (50% of lot area) for R1 properties, with a 20% bonus available for buildings meeting certain design criteria - effectively allowing 60% of lot area. The 2017 amendments reduced the base ratio to 0.45 (45% of lot area), eliminated the 20% green building bonus, reduced the garage exemption from 400 to 200 square feet, and eliminated the 250 square foot exemption for covered porches and breezeways.

What this means in practice: on a standard 7,500 square foot R1 lot in a non-hillside, non-coastal area, the maximum RFA is 3,375 square feet. That includes the garage (minus the 200 square foot exemption per required parking space). On a 5,000 square foot lot - the minimum R1 lot size - the maximum is 2,250 square feet. These numbers are often smaller than owners expect, particularly when they are looking at existing homes on the same street that were built under previous, more permissive rules.

The RFA ratios vary by zone. In the RE zones, which require larger minimum lot sizes, the ratios are lower - ranging from 0.35 to 0.40 depending on the specific zone. The RA zone, intended for suburban agricultural uses, has the lowest ratio at 0.25. The practical effect is that larger-lot zones do not scale proportionally: a 20,000 square foot RE20 lot does not allow 9,000 square feet of home. The code deliberately constrains the house-to-lot ratio on larger parcels.

4. FAR ON HILLSIDE LOTS: THE BASELINE HILLSIDE ORDINANCE

Properties in designated Hillside Areas are governed by a different and more complex floor area calculation under the Baseline Hillside Ordinance (BHO), originally adopted in 2011 as Ordinance No. 181,624 and amended alongside the BMO in 2017. The BHO replaced the previous system, which allowed a floor area ratio of up to 3 times the buildable area (lot size minus setbacks) - a formula that permitted homes dramatically out of scale with their sites and neighborhoods.

The BHO uses a slope band method to calculate maximum RFA. Instead of applying a single ratio to the entire lot, the system divides the lot into bands based on the steepness of the terrain and applies a different FAR to each band. The steeper the slope, the lower the allowable FAR for that portion of the lot. The formula is:

RFA = (A1 x FAR1) + (A2 x FAR2) + (A3 x FAR3) + ...

Where A is the area of the lot within each slope band and FAR is the corresponding ratio for that band in the property's zone.

For R1-zoned hillside properties, the slope band FARs are:

The FARs decrease for larger-lot zones (RS, RE, RA). At 100% slope or greater, the FAR drops to zero across all zones, meaning that extremely steep portions of a lot contribute nothing to the allowable building area.

This calculation requires a slope analysis map prepared by a licensed surveyor or engineer, based on the natural or existing topography. The map delineates the portions of the property within each slope band and tabulates the total area in each. This is not optional - LADBS requires it as part of any permit application on a hillside lot. The cost of the survey and slope analysis typically runs $5,000-$15,000 depending on lot size and complexity, and it is money well spent before you begin design. We cover site investigation requirements in detail in our lot due diligence guide.

For a deeper discussion of how hillside conditions affect construction scope, cost, and feasibility, see our hillside construction guide.

5. SETBACKS: THE BUILDABLE FOOTPRINT

Setbacks define the minimum distance between your building and the property lines. They determine the buildable footprint of your lot - the area within which any structure can be placed. In the R1 zone, the standard setback requirements are:

Front yard: 20% of lot depth, with a maximum required setback of 20 feet. However, the prevailing setback rule can modify this: if 40% or more of the developed lots on the same block frontage have front yards that vary by no more than 10 feet, the required front yard becomes the average of those existing front yards. This means that on an established street where homes are set back 25 feet, a new home may need to match that pattern even if the code would otherwise require only 15 feet.

Side yards: A minimum of 5 feet on each side for buildings up to two stories. For lots less than 50 feet wide, the side yard can be reduced to 10% of lot width, but never less than 3 feet. For buildings taller than 18 feet (in non-hillside, non-coastal areas), one additional foot is required for each 10-foot increment of height above 18 feet. The 2017 amendments also introduced a side wall offset/plane break requirement: any side wall exceeding 14 feet in height with a continuous length greater than 45 feet must include an offset at least 5 feet deep and 10 feet long. This was specifically designed to prevent the flat, unbroken wall planes that characterized many mansionization-era homes.

Rear yard: 15 feet in the R1 zone. In the RE zones, this increases to 20% of lot depth (with a 25-foot maximum for RE9 and RE11, and scaling up for larger zones).

6. HEIGHT LIMITS AND THE ENCROACHMENT PLANE

Height limits in Los Angeles residential zones depend on multiple factors: the base zone, the height district, whether the property is in a Hillside Area or Coastal Zone, and whether any overlays apply.

For standard R1 properties outside of hillside and coastal areas, the maximum height is 33 feet for buildings with a sloped roof (slope greater than 25%). For flat roofs or roofs with a slope of 25% or less, the maximum drops to 28 feet. This distinction is one reason pitched roofs remain common in new construction across the Westside - the additional 5 feet of allowable height provides meaningful design flexibility.

In Hillside Areas, height is measured differently and regulated more stringently. The BHO establishes height limits based on the relationship between the building and the hillside grade, with separate limits for the building envelope height and the overall height. For R1 hillside properties, maximum envelope height ranges from approximately 18 to 28 feet for flat roofs and 22 to 33 feet for sloped roofs, depending on site conditions. Maximum overall height ranges from 25 to 45 feet. The specifics depend on the grade conditions and whether the property is an uphill or downhill lot.

In the Coastal Zone outside of Hillside Areas, maximum height is capped at 45 feet for R1 properties in Height District 1.

7. LOT COVERAGE

Lot coverage limits the percentage of the lot that can be covered by buildings and structures. This is distinct from FAR, which limits total floor area across all stories. A lot can comply with FAR limits while exceeding lot coverage if all the floor area is concentrated on a single story with a large footprint.

In the standard R1 zone, there is no explicit lot coverage maximum separate from what the setbacks and FAR naturally constrain. However, the R1 Variation Zones do impose explicit lot coverage limits, typically ranging from 40% to 55% depending on the specific variation. In Hillside Areas, the BHO limits lot coverage to 40% for R1 properties, with reductions for steeper lots. This is an important constraint on hillside properties, where owners sometimes want to maximize the building footprint on the flatter portion of the site.

8. R1 VARIATION ZONES: THE LAYER MOST PEOPLE MISS

In 2017, alongside the BMO and BHO amendments, the City adopted R1 Variation Zones (Ordinance No. 184,802) - a system of 16 subzones that allow neighborhoods to adopt development standards more tailored to their existing character. These were applied to several neighborhoods across the city and will continue to be applied as community plans are updated.

The variations fall into four categories:

R1V (Variable-Mass) zones offer the most flexible building envelope. They are intended for neighborhoods with a variety of building forms and allow flexibility in where massing is located within the envelope. Four sub-variations (R1V1 through R1V4) have progressively more restrictive FAR limits, height limits, and lot coverage maximums.

R1F (Front-Mass) zones are designed for neighborhoods where the predominant pattern is a two-story mass at the front and a one-story mass at the rear. The code allows taller construction toward the front of the lot and mandates shorter massing at the rear.

R1R (Rear-Mass) zones are the reverse - neighborhoods where the pattern is a one-story mass at the front and taller construction toward the rear. The regulations mandate shorter heights at the front of the lot.

R1H (Hillside) zones apply to hillside properties and establish alternative RFA ratios, height limits, and lot coverage maximums specific to hillside conditions. Four sub-variations (R1H1 through R1H4) provide progressively more restrictive standards.

R1 Variation Zones also eliminated several provisions that existed in standard R1. The 250 square foot exemption for covered porches and breezeways is gone. The garage exemption is reduced from 400 to 200 square feet. The 20% RFA bonus for green buildings is eliminated. The first 100 square feet of ceilings over 14 feet are counted in the RFA calculation. A public hearing is now required to obtain a 10% RFA bonus in non-hillside areas. These changes were specifically designed to close the loopholes that builders had exploited under the original BMO.

Neighborhoods that have adopted R1 Variation Zones include areas in Brentwood, Pacific Palisades, Beverly Grove, and parts of the Valley. Your property's specific variation zone is visible in ZIMAS and encoded in the zoning string.

9. RE AND RD ZONES: LARGER LOT STANDARDS

Several Westside neighborhoods, particularly in Bel Air, Pacific Palisades, and Brentwood, are zoned RE (Residential Estate) rather than R1. The RE zone is subdivided by minimum lot size: RE9 (9,000 square feet), RE11 (11,000 square feet), RE15 (15,000 square feet), RE20 (20,000 square feet), and RE40 (40,000 square feet). These zones carry their own FAR limits, setback requirements, and height restrictions that differ from R1.

RE zones generally have lower FARs than R1. The base BMO ratios for non-hillside, non-coastal RE properties range from 0.35 (RE15 through RE40) to 0.40 (RE9, RE11). Side yards are wider: 10% of lot width (minimum 5 feet, maximum 10 feet) for RE15, compared to 5 feet minimum for R1. Front yards require 20% of lot depth up to 25 feet (versus 20 feet maximum in R1).

The RD zone (Restricted Density Multiple Dwelling) appears in some residential areas and permits two-family dwellings. Properties in RD zones are subject to different standards than R1, including potentially different height limits and different FAR calculations. An RD-zoned property is not governed by the single-family BMO provisions, which can create confusion when owners or agents assume all residential lots follow the same rules.

10. SPECIFIC PLANS AND NEIGHBORHOOD OVERLAYS

Base zoning is only the starting point. Many properties across the Westside are subject to one or more additional layers of regulation through specific plans, neighborhood overlays, or supplemental use districts. These layers can modify nearly every development standard - FAR, height, setbacks, design requirements, grading limits - and the most restrictive standard always governs.

Specific Plans

Specific Plans are the most comprehensive overlay tool. They function as miniature zoning codes for defined geographic areas, with their own development standards and review processes. Properties in the Westside that are commonly affected include those within the Mulholland Scenic Parkway Specific Plan, which covers properties within approximately 3,000 feet of Mulholland Drive from Hollywood Hills to Woodland Hills. The Mulholland Specific Plan imposes height limits of 40 feet measured from the highest point of the roof to the ground surface directly below, requires design review for any project adding 900 or more cumulative square feet of floor area since the plan's adoption in 1992, and subjects visible projects to review by the Mulholland Design Review Board. If your property is within the Mulholland corridor, the permitting timeline will be longer and the design constraints more significant than the base zoning alone would suggest.

The Pacific Palisades Commercial Village and Neighborhoods Specific Plan governs development in four commercial areas of the Palisades, including the central Village and the Marquez, Santa Monica Canyon, and Sunset/PCH commercial districts.

The San Vicente Scenic Corridor Specific Plan affects properties along portions of San Vicente Boulevard in Brentwood.

Historic Preservation Overlay Zones (HPOZs)

Historic Preservation Overlay Zones (HPOZs) add a design review layer to neighborhoods with documented architectural and cultural significance. There are currently 35 HPOZs across Los Angeles, primarily in single-family neighborhoods. If your property is within an HPOZ, virtually all exterior alterations - including painting, window replacement, roof changes, additions, new construction, and even some landscaping - require review by the HPOZ Board. For contributing structures (homes built during the neighborhood's period of significance that retain their historic character), the review ensures changes are compatible with the historic character. For non-contributing structures and new construction, the HPOZ Board reviews massing, orientation, and setback to ensure compatibility with the district. HPOZ review adds both time and design constraints to any project, but it also provides access to the Mills Act property tax reduction program for contributing structures - a meaningful financial benefit.

CDOs, CPIOs, and Conditional Limitations

Community Design Overlays (CDOs) and Community Plan Implementation Overlays (CPIOs) establish design standards for specific areas, often addressing building articulation, fenestration patterns, materials, and landscape requirements.

"D" limitations can be attached to any zone change to impose additional restrictions on height, floor area, or uses. A "Q" qualified condition functions similarly, attaching specific requirements as conditions of a zone change approval. These are property-specific and only discoverable through ZIMAS or a direct review of the planning case files.

11. THE COASTAL ZONE

Properties within the California Coastal Zone are subject to an additional regulatory framework under the California Coastal Act. Within the City of Los Angeles, the Coastal Zone stretches through portions of Pacific Palisades, Playa del Rey, Venice, and San Pedro. Coastal Zone properties are identified in ZIMAS, which also indicates whether the property is in a dual-permit jurisdiction area (requiring California Coastal Commission review) or a categorical exclusion area.

For single-family residential properties zoned R1 in the Coastal Zone but outside of a Hillside Area, the floor area calculation is different from both the BMO and BHO. Instead of the Residential Floor Area ratio, these properties use a Floor Area Ratio of 3 times the Buildable Area of the lot (lot area minus setbacks). This is the older, pre-BMO method of calculation and can actually result in a larger allowable home than the current BMO would permit on an equivalent non-coastal lot.

However, Coastal Zone properties face other constraints. Height is limited to 45 feet in Height District 1. Side yard requirements are calculated differently: one additional foot is required for each additional story above the second story, rather than the incremental height-based calculation used in non-coastal areas. And critically, most development in the Coastal Zone requires a Coastal Development Permit - either from the City (in areas where the City has a certified Local Coastal Program) or from the California Coastal Commission (in dual-permit jurisdiction areas). This adds a significant layer of review, timeline, and potential conditions to any project.

12. HOW TO USE ZIMAS

The City's Zone Information and Map Access System (ZIMAS) at zimas.lacity.org is the essential starting point for understanding what applies to any property in Los Angeles. ZIMAS is free, publicly accessible, and aggregates zoning, planning, and building permit data from multiple city departments.

To look up a property, navigate to ZIMAS and enter the property address, assessor parcel number, or use the interactive map. Once you select a property, ZIMAS displays a summary page with the parcel's zone classification, height district, and lot dimensions.

The information most relevant to understanding buildable area is organized under several tabs and dropdown menus. Under Planning and Zoning, you will find the zone designation (e.g., R1-1, RE15-1-H), height district, and any applicable specific plans, overlays, or supplemental use districts. This section tells you which set of rules applies to the property. Check for Hillside Area designation, Coastal Zone status, HPOZ membership, specific plan applicability, and any "D" or "Q" conditions.

Under Building Permit Info, ZIMAS links to past and current building permits filed with LADBS. This is useful for understanding the permit history of a property and for identifying any open violations or pending cases.

Under Case Numbers, you can see planning entitlement applications and environmental cases associated with the property. If the property has a history of variances, conditional use permits, or zone changes, those cases will appear here.

13. CALCULATING WHAT YOU CAN BUILD: A PRACTICAL WALKTHROUGH

Pulling all of this together, here is the process for determining what a lot allows before you engage an architect or commit to a purchase.

Step 1: Identify the property in ZIMAS. Record the zone, height district, hillside status, coastal zone status, and every overlay or specific plan that applies.

Step 2: Determine which FAR/RFA rules apply. If the property is in a non-hillside, non-coastal area, the BMO applies and the RFA ratio is determined by the zone (0.45 for R1, lower for RE and RA zones). If the property is in a Hillside Area, the BHO slope band method applies and you will need a slope analysis. If it is in the Coastal Zone outside a hillside, the 3x buildable area formula applies.

Step 3: Calculate maximum RFA. For a flat lot, multiply the lot area by the applicable ratio. For a hillside lot, the slope analysis determines the area within each band, and each band is multiplied by its corresponding FAR. Add the RFA exemptions (garage, detached accessory buildings, basement if applicable) to understand total buildable area beyond the RFA number.

Step 4: Apply setbacks to determine the buildable footprint. Calculate front, side, and rear yard requirements based on the zone. Check prevailing setback requirements for the front yard. The remaining area after setbacks is your buildable footprint.

Step 5: Apply height limits and the encroachment plane. Determine the maximum height based on zone, height district, hillside status, and roof type. Map the encroachment plane from the setback lines to understand the three-dimensional building envelope.

Step 6: Check every overlay. Review the specific plan, HPOZ, CDO, or other overlay requirements that ZIMAS identified. Apply the more restrictive standard wherever the overlay and base zoning conflict.

Step 7: Factor in lot coverage, parking, and grading. Confirm lot coverage limits (especially in variation zones and hillside areas). Account for two required covered parking spaces. For hillside properties, check the by-right grading limits (1,000 cubic yards for R1 hillside lots under the BHO) and determine whether your project will require a grading permit or a haul route.

14. COMMON MISTAKES AND MISCONCEPTIONS

Several misunderstandings appear repeatedly in projects we evaluate.

Confusing real estate square footage with RFA. The square footage in a listing is typically calculated differently from the LAMC definition of Residential Floor Area. Garages, covered porches, and below-grade spaces may be counted differently (or not at all) in a real estate listing compared to the zoning calculation. Always calculate RFA using the code definitions, not the listing data.

Not checking hillside status. Hillside designation is not always obvious from the street. Properties that appear relatively flat at street level can be designated Hillside Area if they are within the mapped boundaries. The hillside designation triggers a completely different FAR calculation, different height limits, different setback rules, and different grading standards. Check ZIMAS.

15. WHEN PROFESSIONAL HELP IS REQUIRED

Zoning analysis for a straightforward flat lot in a standard R1 zone is something a knowledgeable owner or architect can handle with ZIMAS and the LAMC. But the complexity escalates rapidly when hillside regulations, coastal zone requirements, specific plans, HPOZs, or multiple overlays come into play. Properties in Pacific Palisades, Bel Air, and the Hollywood Hills frequently involve three or more overlapping regulatory layers.

For these properties, the zoning analysis is not a preliminary exercise - it is a critical feasibility determination that should be completed before committing to a purchase or beginning design. This is the analysis that a qualified construction manager brings to the pre-design phase: not just understanding the rules, but understanding how they interact with the site conditions, the design intent, and the permitting strategy to produce a project that is both buildable and approvable.

The information on this page is provided for educational purposes and reflects the professional experience and perspective of Benson Construction Group. Zoning regulations, ordinance numbers, and development standards cited reflect current conditions for the City of Los Angeles as of the date of publication and may be amended by subsequent legislation. This content does not constitute legal or planning advice for any specific project. Zoning determinations should be verified through ZIMAS and confirmed with the Department of City Planning or a qualified land use professional for project-specific guidance.