Hidden Hills ADUs,
Handled End to End

Most Hidden Hills lots qualify. California state law (Government Code §65852.2) requires every California city to allow at least one ADU on single-family residential lots, and Hidden Hills is its own incorporated city of large equestrian-zoned parcels. What changes per lot is the type and size of ADU that fits, plus how it reads from the bridle paths and street. A detached new-build is common because lots are large — typically one acre or more — and there is room to site an ADU well away from the primary residence and existing equestrian facilities. An attached ADU shares a wall with the primary house and works when an existing wing can absorb a new unit. A garage conversion uses the existing detached-garage footprint and skips many setback rules. A Junior ADU (JADU) is carved out of the existing primary home, up to 500 sq ft with its own entrance and efficiency kitchen — useful when the HHCA Architectural Committee is sensitive to a new exterior structure on a particular lot. We confirm zoning, equestrian setbacks, and HHCA design context at the first site visit and recommend the type that fits the property.

Neither. Hidden Hills is its own incorporated city. ADU permits are issued by the City of Hidden Hills — not Calabasas, not LADBS, and not LA County. We handle the City of Hidden Hills submittal, plan-check corrections, and final inspection — end to end.

Yes. Hidden Hills is a private gated community administered by the Hidden Hills Community Association (HHCA). In addition to the City of Hidden Hills building permit, almost any exterior change — including a new detached ADU, an attached addition, an exterior alteration of a garage being converted, fencing, grading, and many landscape changes — requires HHCA Architectural Committee review and approval. The committee evaluates massing, roof form, exterior materials and color palette, fence and gate detail, equestrian considerations, and how the ADU reads from bridle paths, neighbors, and the street. HHCA review runs in parallel with the City of Hidden Hills plan-check; both have to clear before construction starts. We prepare HHCA submittals as part of the design phase, not as an afterthought.

Three site-condition gates apply on top of standard ADU rules. (1) Hidden Hills is an equestrian community: setbacks from bridle trails, stables, and corrals, plus crossing of equestrian easements, are reviewed by the HHCA Architectural Committee and shape where on the lot an ADU can sit. (2) Hidden Hills lies within a Very High Fire Hazard Severity Zone (VHFHSZ) and is treated as Wildland-Urban Interface (WUI) under Chapter 7A of the California Building Code — ignition-resistant siding and soffits, dual-pane tempered or multi-pane glazing, ember-resistant vents, Class A roof assembly, and defensible-space compliance are required. LA County Fire serves the area for emergency response and reviews defensible-space and access. (3) Large lots mean utility runs are real distances: water, sewer or septic where applicable, gas, and electrical from the primary dwelling to the ADU pad need to be sized, trenched, and inspected. Many Hidden Hills properties also need a panel upgrade to absorb the new ADU load. We size all of this during design rather than discover it in the field.

State law caps required side and rear setbacks at four feet for new detached or attached ADUs and waives setback requirements when you convert an existing garage in its footprint, but local equestrian and HHCA standards often push the ADU envelope farther in. Utilities are real work, not paperwork: water service is by Las Virgenes Municipal Water District; sewer service exists in much of Hidden Hills, with some parcels still on septic — we confirm at the first site visit. Most Hidden Hills homes need a panel upgrade before the ADU electrical load can land. Title 24 (California Energy Code) applies in full: new detached ADUs and significant additions trigger solar PV requirements, mandatory high-efficiency envelope and HVAC, electric-ready provisions for cooking and water heating, and EV-charger-ready circuits where the ADU has parking. We design to Title 24 and CALGreen baseline from day one rather than retrofit at plan-check.

Timeline depends on scope, site conditions, and material lead times. Site visit and feasibility, design and drawings, plan-check, and construction are each scoped during consultation, and we provide a realistic schedule in writing once the design is set. Budget varies with ADU type (detached, attached, garage conversion, JADU), lot conditions, finish level, and any hillside, oak, historic, or HOA review that applies — we provide an itemized written quote after the site visit. Rental income varies by neighborhood, finish, and ADU type, and we model realistic numbers with you. Owner-occupancy: AB 670 and AB 671 mean a detached or attached ADU does not require the owner to live on the property, but JADUs continue to require owner-occupancy of one of the two units. Family use is straightforward — adult children, aging parents, in-law suite, work-from-home flex space — and ADUs configured as family units can later convert to rental without rebuild, provided the design anticipated that path. We provide a written cost breakdown at the consultation.