#1 ADU Contractor in Whittier
Custom Builds by Horizon Remodeling

Finding the right adu contractor in Whittier means understanding a regulatory picture that has been shifting at the state level while local rules add their own layer on top. California consolidated its ADU statutes into Government Code sections 66310 through 66342 in 2024, and those sections were amended again effective January 1, 2026. Under the current law, square footage is calculated as interior livable space, an agency has 15 business days to determine whether a submitted application is complete, and 60 days to approve or deny it. Approval is ministerial, meaning no public hearing and no discretionary design review.

For a Whittier property, that application goes to the City of Whittier Community Development Department and its Building and Safety Division specifically. Because Los Angeles County contains 88 incorporated cities, the counter and the process change from one municipality to the next even when the underlying state statute is identical. That distinction matters: the county’s own ADU ordinance, amended in July 2025 and later found non-compliant with state law by the California Department of Housing and Community Development in December 2025, governs unincorporated territory only. It does not govern Whittier, but it is a useful reminder that a local handout is not always current with what the statute actually says.

Whittier’s housing stock shapes every project before a permit is even filed. The city developed in layers, from its Quaker-founded Uptown core through the postwar tracts that replaced orange groves across wider lots. An older Uptown-era house with a detached structure already on the parcel raises different questions than a postwar tract house where the garage sits closer to the rear property line. We walk the parcel first, checking setbacks, grade, equipment access, and utility routes before a line gets drawn.

One additional local factor carries real weight for properties in Hadley-Greenleaf, Central Park, College Hills, or Earlham. Those four locally designated historic districts require a Certificate of Appropriateness for exterior work. That review runs alongside the standard building permit process through the Building and Safety Division, so the timeline and submittal requirements differ from a non-historic parcel. Knowing which district applies before design begins prevents rework later.

Regardless of where the parcel sits in the city, state law sets a floor of protections that a local agency cannot reduce. A unit cannot be capped below 850 square feet of interior livable space, or below 1,000 square feet if it has more than one bedroom. Side and rear setbacks cannot exceed four feet. Owner-occupancy cannot be required. Adding an ADU cannot trigger a fire sprinkler retrofit on the main house. And there are no impact fees on a unit of 750 square feet or less. Those protections hold across every Whittier neighborhood, and we build every project plan around them from the first site visit forward.