#1 ADU Contractor in Santa Monica
Custom Builds by Horizon Remodeling

Finding the right adu contractor in Santa Monica means working with someone who understands both the state statutes that govern this building type and the local agency that actually processes your paperwork. California consolidated its ADU law into Government Code sections 66310 through 66342 in 2024, and a further revision took effect January 1, 2026. Under the current statute, square footage is measured as interior livable space, an agency has 15 business days to determine whether an application is complete, and 60 days to approve or deny it. Approval is ministerial, meaning no public hearing and no discretionary design review.

In Santa Monica, that application goes to the City of Santa Monica Building and Safety Division. One detail that sets this city apart from most others in the region: if the property includes a designated landmark, Chapter 9.56 of the municipal code requires a Certificate of Appropriateness from the Landmarks Commission before any city department may issue a permit. We identify that condition early so it does not surface as a surprise after drawings are complete and fees are paid.

Los Angeles County contains 88 incorporated cities, and the agency at the counter changes from one to the next even where the underlying state rules do not. The county’s own ADU ordinance, which governs unincorporated territory rather than the cities, was amended in July 2025 and then found non-compliant with state law by the California Department of Housing and Community Development in December 2025. Among other findings, it caps detached ADUs on a multifamily lot at two where state law allows up to eight. That does not apply directly to Santa Monica, but it is a useful reminder that a local handout is not always current with the statute.

Santa Monica’s housing stock shapes the practical side of every project. The city filled in through the early and middle twentieth century, and roughly 73 percent of units are renter-occupied, so a large share of the work involves apartments, condominiums, and older small houses with constrained lots and limited utility access. Those conditions decide whether a garage conversion or a new detached build makes more sense, how far utilities have to run, and where a unit can legally sit relative to setbacks and existing structures. We walk the parcel and check grade, equipment clearances, and utility routes before any drawing begins.

State law sets a floor that no local agency can go below. A city cannot cap an ADU below 850 square feet of interior livable space, or 1,000 square feet for a unit with more than one bedroom. Side and rear setbacks cannot exceed four feet. Owner-occupancy cannot be required. Building an ADU cannot trigger a fire sprinkler retrofit of the main house. And there are no impact fees on a unit of 750 square feet or less. Understanding where state law protects you, and where the City of Santa Monica Building and Safety Division has discretion, is the starting point for every project we take on here.