ADU Builder in The Flats, Beverly Hills

Accessory Dwelling Units on Flats Lots North of Santa Monica Boulevard

The Flats run from Sunset Boulevard down to Santa Monica Boulevard, on the palm- and tree-lined streets that most people picture when they think of Beverly Hills. The City of Beverly Hills permits every ADU here, under its Central Area ADU development guide, and the guide is generous on this side of the boulevard.

The larger of the two new ADU types the city allows (the BHMC 10-3-5001 unit) may be built to 1,400 square feet here, with a detached version allowed to reach 25 feet. That is enough for a two-bedroom cottage with a loft, or a full second story over a rebuilt garage.

The catch is floor area. The 1,400-foot figure only holds if the lot has that much allowable floor area left, and many Flats houses have been enlarged over the years. On those lots, the 800-square-foot minimum, which the city honors regardless of floor area, coverage or front setback limits, becomes the working number.

How 1920s Flats Houses Shape the ADU

Much of the Flats was built out in the 1920s and 1930s, in Spanish Colonial Revival, Mediterranean, Tudor and Colonial styles, and plenty of those houses still stand among newer rebuilds. The typical original plan put the house toward the street, ran a driveway along one side and set a detached garage at the rear. That rear garage is the single most common ADU site in the neighborhood.

Some original garages are worth converting. Others, with shallow footings and decades of settling, are better replaced by a new detached unit in the same spot. We inspect the structure before recommending either. The older houses also tend to bring clay sewer laterals and modest electrical services, both of which need checking before an ADU kitchen goes in. Architecturally, a Flats ADU usually borrows from the main house. A plaster guest house with a low tile roof sits comfortably behind a Spanish revival home, while a half-timbered Tudor might call for steeper roof lines and a different window rhythm.

Large Flats Lots and the Incentive ADU Program

Many Flats parcels are big by Los Angeles standards, especially on the streets closer to Sunset. Beverly Hills offers an Incentive ADU program on single-family lots of 13,000 square feet or more: one additional ADU beyond what state law already allows, as long as one ADU on the property is deed-restricted for rental use with a lease of at least one year.

Combined with the city's baseline of a junior ADU, a conversion ADU and two new ADUs, a large Flats lot can carry several units. Most owners do not want that many. But knowing the ceiling helps when planning a guest house now and leaving room for a second unit later.

Building an ADU on a Flats Street

Construction logistics in the Flats are easier than in the hills but not trivial. Street trees on many blocks are a signature of the neighborhood, and their canopies limit where a crane or a tall delivery truck can work. Long driveways help, but some are narrow, with the house on one side and a wall on the other. Utilities run from the street or alley. Water comes from the City of Beverly Hills, power from Southern California Edison. A deep lot means a long trench back to the ADU, and that distance shows up in the budget.

A few blocks just south of Sunset fall inside the city's Very High Fire Hazard Severity Zone. If your lot is one of them, expect ignition-resistant construction on the ADU and a brush clearance inspection on the yard each spring. We compare both routes before fixing the ADU's position, since a shorter trench can justify shifting the unit a few feet.

• Crane and truck access around street trees
• Long trench runs from the street to a rear ADU
• Clay sewer laterals in original 1920s and 1930s construction
• Fire-zone rules on the blocks nearest Sunset