Your ADU Contractor in Simi Valley

Ask the builder what your lot area is before they draw anything. In Simi Valley that number sets the unit: a detached ADU runs to 1,000 sq ft on a parcel of 8,000 sq ft or less and 1,200 sq ft above that, drops to 800 sq ft on hillside parcels, and picks up a 20 ft front setback once it passes 800 sq ft. A builder who sketches first and measures later is drawing a unit the city will trim. Master Construction designs, permits and builds ADUs across Simi Valley under Lic. #1027281, family owned since 1994, with electrical, plumbing, concrete and roofing on our own crews.

Type comes first: a garage conversion reuses the slab, walls and roof; a detached casita buys a foundation, framing, a roof and, under the 2025 energy code, its own solar. Size is next, with 750 sq ft the line where impact fees switch on and 8,000 sq ft of lot the line between a 1,000 sq ft and a 1,200 sq ft unit. Then the utility runs: the sewer lateral, whether a 100-amp panel can feed a subpanel, and the will-serve letter from Waterworks District 8 or Golden State. Hillside and fire-zone parcels add engineering and WUI construction. The lot walk comes first; the written fixed-price scope follows it.

Permitting and building run on separate clocks. As of 2026 the city has 15 business days to confirm the package is complete and 60 days from a complete application to approve or deny, and Simi Valley's counter adds its own rhythm: completeness review, then a fee link, then plan check. Ventura County Fire and the water purveyor review in parallel under the same clocks. Construction typically runs a few months for a garage conversion and longer for a detached unit, with the panel work, sewer tie-in and cooling scheduled inside that window. Summer concrete gets poured at dawn. The schedule you sign carries review dates and build dates.

No catalog. As of September 2026 the city's Planning Division page publishes an ADU Guide, links to the state HCD handbook and the regional Housing SoCal site, and notes that the ADU ordinance and development standards are being updated; it lists no pre-approved or permit-ready plan sets. State law does require cities to accept a plan identical to one approved in the current code cycle and decide it within 30 days, so ask Planning at (805) 583-6769 whether a specific set qualifies. Otherwise every ADU in Simi Valley goes through full plan check, and we draw the set to the lot, the 8,000 sq ft line and the window-height rule.

Yes, and it is the most common ADU in the city. A conversion inside the existing garage walls has no size limit under SVMC 9-44.160, keeps its setbacks and needs no replacement parking; state law allows 150 sq ft of added floor area for an entry. If only part of a required-parking garage converts, the remainder stays parking when it measures at least 12 ft by 20 ft. The build is what a 1970s garage never had: a slab checked and trenched for plumbing, the door opening reframed with egress windows, insulation, fire separation at the house wall, a subpanel, and cooling. A Zoning Clearance and building permit are required.

Often, smaller. Parcels outside the mapped valley floor boundary fall under Chapter 9-32, which caps an ADU at 800 sq ft. Lots subdivided before July 1986 are exempt from the chapter's grading standards unless the work touches a ridgeline, ground over 20 percent or 1,000 cubic yards; whether that also lifts the cap is Planning's call, asked before we draw. Much of the rim is in a Very High or High fire zone; a Very High parcel builds to the WUI code (formerly Chapter 7A) with 100 ft of defensible space, and Ventura County Fire reviews access and fire flow. Santa Susana Knolls and Box Canyon permit through the county.

Yes, for terms of 30 days or more. SVMC 9-44.160 sets that minimum for the ADU, the JADU, and the main house if the owner lives in the unit, so a Simi Valley ADU is a long-term rental by code. There is no owner-occupancy requirement for a standard ADU, so a non-resident owner can build and rent one. The city asks for an ADU Occupancy and Rents Survey with the permit because state law requires it to track every unit; it is a reporting form, not rent control. Demand follows the 118 and Metrolink commute, with Adventist Health Simi Valley, the industrial parks and Moorpark College in range.

No. Civil Code 4751 voids any CC&R provision that prohibits or unreasonably restricts an ADU or JADU on a single-family lot, and Civil Code 714.3, amended in 2025, says a reasonable restriction may not include fees or other financial requirements. What a Wood Ranch, Big Sky, Long Canyon or Bridle Path board keeps is objective architectural review: materials, colors and placement that do not add unreasonable cost or block the unit. Most of the valley-floor tracts have no HOA. Where there is one, we build a single package that answers the board's review and the city's Zoning Clearance, and boards get the same written feasibility read an owner does.

Yes, on one contract. The feasibility read opens the job: lot area against the 8,000 sq ft line, hillside and fire-zone lookups, an oak survey, panel capacity, the sewer lateral, and which water purveyor serves the address. Design-build comes next, with the price tracking the drawings, the set built for the city's CSS portal and the will-serve request filed alongside it. Our own crews then run the concrete, framing, electrical, plumbing, drywall, roofing and cooling through final inspection under a single schedule and a single fixed price. Call (805) 667-8800 and we will start with the lot.