A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateADU Company in Simi Valley, CA
Adding an ADU or home addition in Simi Valley means working with specific lot shapes, hillside setbacks, and a planning department that sees a steady flow of accessory dwelling unit applications. Homeowners here typically call us wanting a straight answer: what will it cost, who’s actually showing up, and will the price change once work begins. We give you a written price before we start, and every person who comes to your property is background-checked, identity-verified, and photo-badged under the Threshold Standard. Call (472) 248-8213 for a free estimate.
Why Simi Valley Homes Are Different
Simi Valley sits in a valley bowl with summer temperatures that regularly push past 95 degrees and dry, windy conditions in the fall. That shapes how we build. Stucco and concrete tile roofs dominate older tracts built from the 1960s through the 1980s, and many of those homes have slab foundations that need careful evaluation before an addition ties in. Newer subdivisions on the east side, around neighborhoods like Indian Hills and Wood Ranch, tend to have larger lots but stricter HOA design review for detached structures. Hillside lots in the Santa Susana foothills add grading and retaining wall costs that flat-lot ADUs never see. Simi Valley’s planning department requires standard California ADU setbacks, typically four feet from side and rear property lines, but the real variable is fire zone mapping. Homes in designated high fire hazard severity zones must use specific exterior materials and venting details. A James Hardie fiber cement exterior is often the simplest path to approval on those lots. If your street is in a flood zone along Arroyo Simi, expect additional drainage review before permits are issued.
Our Main Simi Valley Services
The two calls we get most from Simi Valley homeowners are about detached ADUs and room additions, with garage conversions close behind. Each service has its own Simi Valley page with pricing, timelines, and permit details.
Home Addition Contractor in Simi Valley
A home addition in Simi Valley usually means extending a single-story ranch or adding a second story over a garage. The foundation work is the part that surprises people. Many older slabs in the central neighborhoods were poured without rebar and need reinforced footings before framing starts. We handle that, plus the structural engineering, the title-24 energy calcs, and the permit set. You’ll know the total price in writing before demolition day. See more on our Home Addition Contractor in Simi Valley page.
ADU Builders in Simi Valley
Detached ADUs are the fastest-growing project type in Simi Valley, and the lot is usually the deciding factor. Corner lots and homes with wide side yards tend to have the fewest complications. Setbacks, fire-zone cladding rules, and utility trenching are the three things we evaluate on the first walkthrough. We build both site-built and prefab units from brands like Abodu and Dvele, and we’ll tell you honestly which approach fits your lot and budget. Full details are on the ADU Builders in Simi Valley page.
Room Addition Contractor in Simi Valley
A room addition, whether it’s a primary suite, a home office, or an expanded kitchen, has to work within Simi Valley’s existing rooflines and setback rules. We see a lot of additions that encroach on the required gap between structures, especially on older lots where the original home was built close to the property line. A site survey clears that up before any design work happens. You’ll get a written price and a vetted, photo-badged crew. Details are on the Room Addition Contractor in Simi Valley page.
What happens when you call
- 1
A real person answersNo phone trees - you reach a local pro.
- 2
You get an upfront price rangeHonest numbers before anyone is dispatched.
- 3
A background-checked tech heads outLicensed & insured, dispatched right away.
- 4
You approve before work beginsNothing starts until you say go.
Brands We Service in Simi Valley
We have direct experience with prefab and modular systems from Abodu, Cover, Mighty Buildings, and Dvele. We also work with Tuff Shed structures and James Hardie cladding systems. Parts and finish materials are sourced locally where possible, and our familiarity with these product lines means fewer surprises during installation. Read more on our brands page.
Pricing for ADU Company in Simi Valley, CA
| Service | Typical range in Simi Valley |
|---|---|
| Detached ADU, 400 – 600 sq ft | $180,000 – $260,000 before site work |
| Detached ADU, 600 – 800 sq ft | $220,000 – $320,000 before site work |
| Detached ADU, 800 – 1,000 sq ft | $280,000 – $390,000 before site work |
| Garage conversion ADU | $90,000 – $180,000 |
| Prefab ADU (Abodu, Cover, or similar) | $160,000 – $300,000 installed |
| Home addition, 200 – 400 sq ft | $90,000 – $180,000 |
| Home addition, 400 – 700 sq ft | $140,000 – $280,000 |
| Room addition, single room 150 – 250 sq ft | $70,000 – $130,000 |
| Room addition, primary suite 300 – 450 sq ft | $110,000 – $200,000 |
| Fire-zone cladding upgrade (James Hardie) | $18 – $35 per sq ft |
| Retaining wall, per linear foot | $250 – $500 |
Hillside lots in Simi Valley can push a project up fast: grading, retaining walls, fire-zone materials, and longer utility runs all add cost. That’s why we give you a written price before any work begins, and the 365-Day Done Right Promise covers defects in workmanship for one full calendar year from project completion.
Neighborhoods We Serve in Simi Valley
We work across the entire city, from the hillside homes in Santa Susana Knolls to the newer tracts in Wood Ranch and everything between. Our scheduling team coordinates crews from the Los Angeles office, and most Simi Valley estimates are scheduled within a few days of your call.
- Wood Ranch
- Indian Hills
- Texas Tract
- Central Simi Valley
- Santa Susana Knolls
Service Area – Cities Near Simi Valley
We also serve homeowners in the neighboring communities of Moorpark, CA, Oak Park, CA, Thousand Oaks, CA, and Westlake Village, CA. If you’re just over the city line, call us and we’ll confirm coverage for your street.
Serving Simi Valley, CA - Our Local Coverage Area
We’re based in the Simi Valley area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs About ADU Company in Simi Valley
Plan on two to four months for plan check and permit issuance in Simi Valley, depending on whether your lot is in a fire hazard zone or requires a hillside grading review. We handle the permit set and submissions so you don’t have to track down a planner yourself. Call (472) 248-8213 to get your project started.
Yes, if you live in an HOA-governed neighborhood like Wood Ranch or Indian Hills, you’ll need design review approval in addition to city permits. California law limits what HOAs can restrict on ADUs, but an architectural review is standard. We prepare submission packets for that step too.
No. You receive a written price before any work begins, and that’s the number on your final invoice unless you ask for a change to the project scope. No surprise invoices, no silent scope creep. Call (472) 248-8213 for a free estimate and a written quote.
What happens when you call
- 1A real person answersNo phone trees - talk to a local adu pro.
- 2You get an upfront price rangeHonest numbers before anyone is dispatched. No surprises.
- 3We come out and measureLicensed & insured, at a time that suits you - the visit and the quote are both free.
- 4You get the price in writingLine-itemed, yours to keep, and nothing starts until you say go.
What Simi Valley Customers Say
"Itemized estimate with allowances laid out. Final cost was within a hair of the quote."
- Naomi R."Backyard ADU for my mother. The project manager showed ID and walked me through the permit steps, the foundation plan, and the schedule. Moved her in on time."
- Margaret C."Insulated the walls and ceiling properly. It stays comfortable even in July."
- Tamika W.
