Your ADU Contractor in Somis

The one who asks about your septic tank before your floor plan. A Somis ADU lives or dies on Environmental Health's certification of the existing system, the water source, fire access on the driveway and the AE zoning tier, and any ADU contractor in Somis should be able to explain each one for your parcel. Master Construction has worked the Las Posas Valley since 1994, family owned, licensed and insured under Lic. #1027281, and runs the county Zoning Clearance, the septic package and the build under one contract. Ask any builder how they handle a full OWTS certification. The answer tells you what you need to know.

The septic answer drives it more than the square footage. If the existing system certifies for the added bedrooms, you are building a house; if it lacks capacity or reserve area, a new engineered system joins the scope. After that come the feeder run from the house or meter, whether a generator and a water storage tank for fire flow are required, the size tier you choose, a county standardized plan versus custom drawings, WUI construction if the parcel maps Very High, grading on a sloped pad, and finishes. Site work on acreage can rival the building. We walk the parcel first, then write a fixed-price scope.

Longer than in a city, and the front end is the reason. Septic certification, a pump report, well or water company proof and any soils work happen before the county package goes in, and Environmental Health review runs about three to four weeks. As of 2026 the county has 15 business days to confirm the application is complete and 60 days to decide, or 30 days on a county standardized plan. Construction on a detached unit then runs several months, with feeder trenching and the slab in front of framing. Plan on the better part of a year from the first site walk to keys.

Yes, three of them, free. The county's standardized plans are a 700 sq ft one-bedroom, a 900 sq ft two-bedroom and a 1,188 sq ft three-bedroom, prepared by the Planning Division and already reviewed by Building and Safety. You can change paint, siding, trim and light fixtures but not the size or the door, vent and plumbing locations. A Zoning Clearance and building permit are still required on AE land, and the site-specific package, septic, water, fire access, grading and soils, is still yours to assemble. Custom units up to the 1,200 sq ft or 1,800 sq ft tier use a full drawing set instead.

Yes, and it is often the cleanest path. A conversion of an existing garage, barn or workshop needs no new setbacks, no replacement parking and up to 150 sq ft of added floor area for a proper entry. On AE land it still takes a Zoning Clearance and it still counts as your one ADU. The work is what the outbuilding lacks: a slab with a vapor barrier, insulation, egress windows, a kitchen and bath, and drains to the septic tank, which means the full OWTS certification because fixtures are being added. An outbuilding standing inside the leach field's reserve area is not a candidate at all.

It means Environmental Health signs off before Building and Safety does. Adding an ADU changes wastewater volume, so the county requires a full certification of the existing onsite system: a plot plan showing the tank, leach field and reserve area against the new construction, a pump report from a county-permitted pumper, bedroom-equivalent and fixture-unit calculations, and a soils report if asked. Tank size follows bedrooms and fixtures; field size follows percolation. If the system falls short, a Registered Civil Engineer, Professional Geologist or Environmental Health Specialist designs a new one for the unit. Either way the leach field and its reserve are open ground the ADU cannot sit on.

Yes, for terms longer than 30 days. The county's ordinance requires every ADU to rent for terms over 30 consecutive days, and a deed restriction recorded at your expense repeats that rule, so a vacation rental is off the table. There is no owner-occupancy requirement for a standard ADU, and the unit may be rented separately from the main house though never sold separately. The county also asks for an estimated rental amount on the permit form. In practice most Somis units house family, a caretaker or a ranch hand; the rare long-term tenant tends to commute to Camarillo employers such as the naval base or the university.

Not with a blanket ban. Civil Code 4751 voids any CC&R provision that prohibits or unreasonably restricts an ADU on a lot zoned single-family, Civil Code 714.3 applies the same rule to deed covenants outside an association, and reasonable restrictions cannot include fees. Most Somis acreage is zoned AE rather than single-family, so we read a gated community's CC&Rs before design and expect its board to keep review of materials and placement. The mutual water company is a different conversation. It cannot veto the permit, but state law lets a water supplier require a separate connection with a proportionate fee for a new detached unit, and a share under the basin adjudication has limits.

Yes, under one contract from the site walk to the certificate of occupancy. The feasibility read comes first: zoning tier, septic capacity and reserve area, water source, fire access and grading. Design-build follows, either on a county standardized plan or a custom set, priced as it is drawn. We assemble the Zoning Clearance, the Environmental Health package and the building permit, answer corrections, and then our own crews run the slab, feeder trench, framing, plumbing, roofing and finish through final inspection. Mountain Fire lots get the rebuild sequence worked out with RMA up front. Call (805) 667-8800 to start with the site walk.