#1 ADU Contractor in Commerce
Custom Builds by Horizon Remodeling

Finding the right adu contractor in Commerce means understanding a permit process and a housing stock that differ from what you find in newer suburban cities. California consolidated its ADU law into Government Code sections 66310 through 66342 in 2024, and a further update took effect January 1, 2026. Under those rules, square footage is measured as interior livable space, an agency has 15 business days to determine whether your application is complete, and 60 days to approve or deny it. Approval is ministerial, meaning no public hearing and no discretionary design review.

In Commerce, that application goes to the City of Commerce Building and Safety Division. That matters because Los Angeles County contains 88 incorporated cities, and the agency, the counter, and the staff reviewing your plans change from one city to the next even when the underlying state statute does not. A handout from a neighboring city or an outdated local guide can send a project in the wrong direction before a single wall is framed. The county’s own ADU ordinance, which governs unincorporated territory rather than incorporated cities like Commerce, 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 the findings, it caps detached ADUs on multifamily lots at two where state law allows up to eight. That ordinance does not apply inside Commerce’s boundaries, but it illustrates why reading the current statute matters more than relying on any local summary.

Commerce grew around a railroad that arrived in 1887 and factories that followed in the 1920s. The city incorporated in 1960 specifically to protect that industrial land from annexation. Houses here sit in small residential pockets hemmed in by freight rail lines, truck routes, and industrial parcels, and the typical home is a small older single-family house or duplex on a modest lot with a narrow galley kitchen and limited room to expand sideways.

That physical reality shapes nearly every ADU decision on a Commerce parcel. A tight lot influences where a detached unit can sit, how far utility lines have to run, and whether a garage conversion is a more practical path than new detached construction. We walk the parcel and check setbacks, grade, equipment access, and utility routes before anything gets drawn. That field review is the step that keeps a promising design from running into a wall once the permit application is open.

State law provides a set of protections that apply regardless of what a local agency might prefer. A local agency cannot cap an ADU below 850 square feet of interior livable space, or below 1,000 square feet if the unit has more than one bedroom. Side and rear setbacks cannot exceed four feet. Owner-occupancy cannot be required as a condition of building an ADU. Construction of 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. Knowing these floors before you sit down with a plan set keeps the project on solid ground from the first conversation.