What Santa Monica Allows.
Santa Monica reviews ADUs as ministerial projects: no design review, no public hearings, just a building permit. The rules live in Santa Monica Municipal Code Section 9.31.025, and the city publishes plain-language ADU guides that spell out every standard.
A single-family lot can stack several units: one converted ADU, one JADU of up to 500 square feet, and one newly built detached ADU, and parcels in the R1 zoning district can add one more attached or detached ADU on top of that. Owner occupancy is not required for an ADU (it is for a JADU), short-term rentals under 30 days are not allowed, and Santa Monica goes further than most cities by letting ADUs be sold separately as condominiums under SMMC Section 9.31.026. Not sure what your parcel qualifies for? Check your lot and we will map it for you.
Size, Height, and Setback Rules.
For a new detached ADU, Santa Monica allows up to 850 square feet for a studio or 1-bedroom and up to 1,200 square feet for two or more bedrooms, with a 150 square foot minimum. Height is capped at 2 stories or 24 feet, and the unit must sit at least 4 feet from the side and rear property lines, outside the front setback, and at least 4 feet from the main house.
Two homeowner-friendly details stand out: ADUs are exempt from the parcel's floor area calculations, so your backyard home does not eat into what you could otherwise build, and no on-site parking is required (parcels in the Coastal Zone should confirm parking with the California Coastal Commission). Abodu's line of backyard homes is sized to fit comfortably inside these limits.
Coastal Zone and Permit Timeline.
Part of Santa Monica sits within the California Coastal Zone. The city's ADU guide notes that parcels in the Coastal Zone may need a Coastal Development Permit or Waiver through the California Coastal Commission before the building permit is approved, so factor that step into your schedule. Properties listed on the California Register of Historical Resources can also face additional standards.
Once you submit a complete application, state law is on your side: under California Government Code Section 66317, the city must approve or deny a complete ADU application within 60 days, and an application left undecided past that window is deemed approved. Santa Monica has also launched a Preapproved ADU Program under AB 1332 that offers expedited review for standardized detached ADU plans. Abodu manages the entire permit package for you; see how the process works.
ADUs on Multifamily Properties.
Santa Monica's multifamily allowances are generous. On a parcel with an existing multiple-unit building, owners can convert non-livable space (storage, garages, basements) into at least one ADU or up to 25 percent of the existing unit count, and can additionally build up to 8 new detached ADUs, capped at the number of existing primary units. New multifamily projects can include up to 2 detached ADUs. The same 850 and 1,200 square foot size limits, 24 foot height cap, and 4 foot setbacks apply, and no on-site parking is required. If you own or operate apartment properties, see how Abodu handles multifamily ADU deployments at scale.
What It Actually Costs.
Custom site-built ADUs in California routinely exceed $250,000 before change orders, and the final number usually is not known until the project is nearly done. Abodu works differently: transparent published pricing: homes from $234,800 plus a published installation price, an expected all-in from $298,800 that covers design, permits, factory build, delivery, and installation. No surprise line items, no open-ended timelines. See how the process works.