#1 ADU Contractor in Duarte
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Working as your adu contractor in Duarte means understanding a permitting environment that operates differently from many neighboring cities. California consolidated its ADU statutes into Government Code sections 66310 through 66342 in 2024, and those rules were updated again on January 1, 2026. Under the current framework, square footage is measured as interior livable space rather than overall building area. Once you submit an application, the reviewing agency has 15 business days to determine whether it is complete and 60 days to approve or deny it. Approval is ministerial, meaning no public hearing and no discretionary design review.

In Duarte, that application goes to the City of Duarte Building and Safety Division. One detail that affects scheduling is worth knowing upfront: the city provides building and plan check services through an outside contract rather than in-house staff. That arrangement shapes how plan review cycles and inspections get coordinated, so we account for it when we map out a project timeline with you.

Los Angeles County contains 88 incorporated cities, and the permitting counter changes from one to the next even where state rules stay constant. A county-level development worth noting: the county’s own ADU ordinance, amended in July 2025, was 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 a multifamily lot at two where state law allows up to eight. That ordinance covers unincorporated territory rather than cities like Duarte, but it is a useful reminder that a local handout is not always current with the statute.

The lot itself decides most of the practical questions. Duarte grew primarily during the 1950s and 1960s suburban wave surrounding the city’s 1957 incorporation, and the typical home is a modest single-story house. On the north side, parcels rise toward the San Gabriel Mountain foothills on sloped ground, which affects where a detached unit can sit, how far utilities need to run, and whether a garage conversion or a new detached structure makes more sense. We walk every parcel and check setbacks, grade, equipment access, and utility routes before anything gets drawn.

State law sets a floor of protections regardless of where the parcel sits. A local agency cannot cap an ADU below 850 square feet of interior livable space, or below 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, and adding an ADU cannot trigger a fire sprinkler retrofit of the main house. Units of 750 square feet or less carry no impact fees.