Santa Monica Above-Garage ADUs and Two-Story Units

Why Santa Monica Owners Build ADUs Upward

Ground is the scarce resource on most lots in this city. A 50-foot-wide parcel with a house, a driveway and a garage leaves little yard, and a single-story cottage would swallow what remains. Going up lets the ADU take roughly half the footprint for the same floor area, or the same footprint for twice the space.

The city's local standards make this realistic. A detached unit may be two stories or 24 feet tall under the ADU guide, comfortably more than the 16-foot minimum set by state law. That gives room for a full second level with a pitched roof, not a cramped loft squeezed under a flat one.

Can the Existing Garage Carry a Second Story?

Usually not. Most Santa Monica garages were built as light sheds on shallow footings or a thin slab. They were never designed to hold a floor, walls and a roof above them, plus the lateral loads an earthquake brings. In most cases the practical route is to remove the old garage and put up a new two-level building with proper foundations, shear walls and a garage or living space below.

There are exceptions. A garage built more recently, on real footings, sometimes can be reinforced rather than replaced. A structural engineer makes that call after looking at the foundation and framing. We would rather tell you early that the garage has to go than design around a structure that cannot carry the load.

• New footings sized for two floors
• Shear walls for seismic loads
• Rated floor between garage and unit
• Exterior or interior stair
• Window placement for neighbor privacy

Two-Story ADUs on Narrow Ocean Park and Pico Lots

Ocean Park has some of the tightest parcels in the city, many dating from the early 1900s, with older garages tucked against the alley. A two-level unit over a rebuilt garage can add a one-bedroom without losing the small yard behind the house. Beach-side parcels can fall inside the Coastal Zone, which brings its own permit question, so we pull up the map before sketching.

In the Pico neighborhood, where many lots carry a house and an older rear structure, building up can let an owner add a unit while keeping parking or storage at ground level. North of Montana, owners with bigger lots sometimes choose two stories for a different reason: to fit a two-bedroom unit while protecting a mature tree or a pool.

Two-Story ADU Privacy, Stairs and Height

A second story sees over fences. That is the main source of friction with neighbors, even though the city reviews ADUs ministerially and neighbors cannot block a compliant project. We design upper windows to face your own yard or the alley, use clerestory windows on the sides, and keep balconies modest.

The stair also shapes the plan. An exterior stair saves interior floor area but needs space in the setback and weather protection. An interior stair costs square footage but keeps the building compact. On very narrow lots, an interior stair is often the only one that fits.

Cost Drivers for a Two-Story ADU

Two-story units carry costs that single-story ones do not: deeper footings, more engineering, a rated floor between levels, stairs and more scaffolding during construction. On the other hand, a smaller footprint means less foundation and roof per square foot of living space.

Demolition of the old garage, utility runs to the new structure, and the choice between keeping parking on the ground floor or making the whole building living space round out the budget. If the ADU itself stays at or under 750 square feet, state law bars impact fees, even with a garage below.