Journal ·
Beverly Hills House Size Limits: Floor Area, Basements and the 50% Rule
In the Central Area of Beverly Hills, all buildings on a single-family lot together may hold 1,500 square feet plus 40 percent of the site area, so a 7,500 square foot lot allows 4,500 square feet. North of Sunset the Hillside Area uses a different formula built on the level pad and the slope, and a separate rule decides when a remodel of an older house has to meet today's standards in full.
Beverly Hills is its own city. Inside city limits, Los Angeles rules such as the Baseline Mansionization Ordinance do not apply, and neither does LADBS. Some homes with a Beverly Hills mailing address sit in the City of Los Angeles instead, so confirm the parcel's jurisdiction first. The numbers below come from the Beverly Hills Municipal Code, Title 10, Chapter 3.
Which part of Beverly Hills is the lot in?
The code splits single-family land into three areas, and each has its own article of standards. The definitions in BHMC 10-3-100 set the lines:
- Hillside Area: generally north of Sunset Boulevard, other than Trousdale Estates, following the Hillside District boundary on a diagram kept by Building and Safety.
- Trousdale Estates: its own set of standards in Article 26.
- Central Area: everything else.
The city's own Central Area single-family page points to Article 24 for floor area, height, setbacks, parking and accessory structures. Before running any formula, confirm which of the three the parcel sits in. A lot near the Sunset line can look like a flat Central lot and still fall on the Hillside side.
How much floor area does a Central Area lot allow?
BHMC 10-3-2402, subsection B, caps the cumulative floor area of all buildings on the site at 1,500 square feet plus 40 percent of the site area. The cap covers the main house, any accessory buildings that count as floor area, and both units in a two-primary-unit project. Accessory dwelling units follow separate state and city rules.
Three details in the same section change real outcomes:
- A primary house must have at least 1,600 square feet and be at least 20 feet wide at its widest point.
- If a lot is subdivided, the primary units on the new lots together may not exceed the cap that applied to the original lot. Splitting a parcel does not create a second full allowance.
- Land dedicated to the city for a street or alley counts toward site area for the project that triggered the dedication, but not for later development, including additions.
The maximum can be modified by a Central Area R-1 permit under Article 24.5. The section's history line shows amendments by Ordinance 25-O-2913, effective May 6, 2025, and Ordinance 25-O-2915, effective June 17, 2025, so a summary written before mid-2025 may not match the current text.
What counts as floor area, and what does not?
The definition in 10-3-100 does most of the work. For single-family zones, floor area is space that has a roof or floor level above it and is enclosed by exterior walls by more than 50 percent. An upper level counts where it is not separated from the level below by a floor/ceiling assembly, so open volume above a lower floor can add to the total.
Two exclusions matter most to buyers comparing listings:
- Basements are excluded from floor area. A basement is a level directly below a story whose finished floor is no more than 3 feet above finished grade. Partial basements are not permitted: a level is either all basement or all floor area. Stairs leading to a basement count as basement.
- Up to 400 square feet of garage is excluded.
A listing's square footage and the code's floor area are therefore different numbers. A house marketed at 6,000 square feet may carry a large basement that the formula ignores, or a garage that only partly counts.
How does the Hillside Area formula work?
BHMC 10-3-2502 starts from the level pad, not the whole lot. A level pad only counts if it contains a level, square area at least 20 feet on each side.
| Hillside site | Maximum cumulative floor area |
|---|---|
| No pad, or pad under 750 sq ft, average slope 20% or more | 20% of site area |
| Site of 15,000 sq ft or less | 40% of level pad + 10% of slope area |
| 15,001 to 25,000 sq ft | 37% of level pad + 10% of slope area |
| 25,001 to 30,000 sq ft | 34% of level pad + 10% of slope area |
| Over 30,000 sq ft | 31% of level pad + 10% of slope area |
Three limits sit on top of the table. An owner may build up to 4,500 square feet even where the formula yields less. And floor area plus all basement floor area may not exceed 15,000 square feet unless a Hillside R-1 permit is issued, with up to 1,600 square feet of basement garage and 300 square feet of basement mechanical area left out of that count. Floor area built off the existing level pad is limited to 1,000 square feet without a Hillside R-1 permit. Sites of two acres or more can go past the table only with a Hillside R-1 permit.
A worked comparison
Here is how the two formulas treat three sites. The Hillside rows assume the pad and slope split shown; the real split comes from a survey.
| Site | Area rules | Calculation | Maximum floor area |
|---|---|---|---|
| 7,500 sq ft flat lot | Central, 10-3-2402 | 1,500 + 40% x 7,500 | 4,500 sq ft |
| 12,000 sq ft flat lot | Central, 10-3-2402 | 1,500 + 40% x 12,000 | 6,300 sq ft |
| 20,000 sq ft site, 8,000 pad, 12,000 slope | Hillside, 10-3-2502 | 37% x 8,000 + 10% x 12,000 = 4,160 | 4,500 sq ft (floor allowance applies) |
The third row shows how much the level pad drives a hillside result. A 20,000 square foot site with an 8,000 square foot pad computes to only 4,160 square feet and is lifted to the 4,500 square foot allowance, well below the 6,300 square feet allowed on a 12,000 square foot Central lot.
When does a remodel have to meet today's code?
Many Beverly Hills houses were built under older standards and are legally nonconforming: a setback or height that would not be allowed now. BHMC 10-3-4100, subsection A.1, lets an owner replace or reconstruct at most 50 percent of the combined area of all exterior walls and roof in any five-year period. Past that line, the building is treated as new and must be rebuilt to conform with current development standards.
The Community Development Department's policy PLNG-001, effective November 14, 2011, explains how staff measure it:
- Window and door openings count as wall area.
- A wall or roof section counts as replaced once its framing is replaced. If the framing around an opening is replaced, the whole opening counts.
- Roof area is the horizontal area covering the floor area, so patios and overhangs are left out.
- New windows set in the same opening without touching the framing do not count. Shear wall sheathing added to existing framing does not count either.
- Between 40 and 50 percent, a separate demolition permit is required before the building permit.
The five-year window is rolling, so earlier permitted work counts. A seller who replaced a third of the combined exterior wall and roof area three years ago has already used two-thirds of the allowance, and a buyer planning a second phase inherits that count.
What to check before making an offer
A short list for a Beverly Hills single-family purchase where size or a remodel matters:
- Confirm whether the parcel is in the Central Area, the Hillside Area or Trousdale Estates.
- Run the floor area formula for that area against the lot or pad survey, not the listing's square footage.
- Ask how much of the stated size is basement and how much is garage, since both are treated differently.
- Pull permit history for the last five years and tally exterior wall and roof work against the 50 percent limit.
- If the plan needs more floor area or height than the base rules allow, ask Planning whether a Central R-1 permit, or for Hillside sites of two acres or more a Hillside R-1 permit, is realistic before relying on it.
Zoning questions go to the Planning Division's public counter at 455 North Rexford Drive.
Buyers comparing other cities on the same question can read how Burbank caps house size by lot size, how Glendale's R1 floor area ratio works, and how Pasadena's compatibility permit is triggered. Sellers can start with a home valuation that separates code floor area from marketed square footage, and buyers can see how Alla works on the buying side.
This article summarizes the Beverly Hills Municipal Code as published in October 2026 and is not legal or architectural advice. Confirm the current text and any pending amendments with the Beverly Hills Planning Division before relying on a figure. Call Alla at (818) 699-5367 or use the enquiry form.
More on the cities Alla covers: the area guides.