A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateADU Company in West Hills, CA
An ADU in West Hills usually costs between $180,000 and $420,000 for a detached unit, $120,000 to $260,000 for a garage conversion, and $200,000 to $500,000 for a home addition. The final number depends on things most West Hills homeowners don’t see coming at first: a 1960s ranch on a flat 7,500 sq ft lot with original electrical panels and cast iron plumbing needs different work than a hillside lot north of Roscoe Blvd. We write every price down before we touch a tool, so you know exactly what your specific lot will require. Call (805) 309-3462 to talk through your property.
Why West Hills Homes Are Different
West Hills is mostly single-family ranch homes built between the 1960s and 1980s, sitting on lots that often run 7,500 to 10,000 sq ft. That’s good news for a detached ADU: there’s room. The less visible part is what’s in the walls and under the slab. Many of these homes still carry their original 100-amp electrical panels, which cannot support an ADU’s mini-split HVAC, range, and washer-dryer load without an upgrade. Cast iron plumbing from the same era often needs replacement before any new bathroom ties in. Then there’s the terrain. Properties north of Roscoe Blvd, up against the Santa Susana Mountains, frequently trigger Hillside Construction Regulations, which means grading, retaining walls, and foundation engineering that flat-lot neighborhoods like Canoga Park or Woodland Hills never deal with. Summer temperatures above 100°F make insulation and efficient cooling a practical necessity in West Hills, not an upgrade. Winter rains, when they come, demand roof flashing and drainage done right the first time. We plan for all of it before a crew shows up.
Our Main West Hills Services
Most West Hills homeowners call us about one of three projects: adding square footage to the main house, converting an attached garage, or building a detached ADU in the back yard. Each one has its own West Hills page with pricing, timelines, and what to expect at your address.
Home Addition Contractor in West Hills
Adding a primary suite or a family room to a 1960s ranch in West Hills means tying new framing into a stucco exterior that has settled for fifty-plus years. We start with the foundation and roofline because those are the two places where a poorly planned addition shows itself within the first rainy season. On hillside lots north of Roscoe Blvd, the addition usually requires a soils report and possibly a retaining wall, which changes the permit timeline. See typical ranges and how we handle the pre-construction work on the Home Addition Contractor in West Hills page.
Garage Conversion Contractor in West Hills
West Hills garages from the 1960s and 70s were built as car storage, not living space. That means a conversion here almost always involves cutting into the slab to run new plumbing for a bathroom, replacing the garage door opening with a weather-sealed wall, and adding insulation that meets current Title 24 requirements. It’s one of the most cost-effective ways to create a rental unit or a quiet guest suite on a flat West Hills lot. We cover the full build process and local permit realities on the Garage Conversion Contractor in West Hills page.
ADU Builders in West Hills
A detached ADU on a large West Hills lot gives you a true second home on your property: separate entrance, own kitchen and bath, and real privacy from the main house. The site work is where West Hills lots separate themselves. Flat lots south of Roscoe Blvd are often straightforward; hillside parcels need grading and retaining before the foundation can go in. Electrical service upgrades and sewer line connections are the two most common hidden scopes we identify during the estimate. We walk through all of it on the ADU Builders in West Hills 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 West Hills
We work directly with Abodu, Cover, and Dvele for homeowners who want a prefab ADU, and we also handle Mighty Buildings units. Each brand has different lead times and site requirements, so we help you match the product to your specific West Hills lot. See our brands for the full comparison.
Pricing for ADU Company in West Hills, CA
These are the numbers we quote most often for West Hills properties. Every line item assumes a standard scope; hillside work, electrical panel upgrades, and sewer line replacement will move the total.
| Service | Typical range in West Hills |
|---|---|
| Detached ADU (1 bed / 1 bath) | $180,000 – $260,000 |
| Detached ADU (2 bed / 2 bath) | $280,000 – $420,000 |
| Garage conversion (studio) | $120,000 – $170,000 |
| Garage conversion (1 bed / 1 bath) | $150,000 – $210,000 |
| Garage conversion (2 bed / 1 bath) | $190,000 – $260,000 |
| Home addition (primary suite) | $200,000 – $320,000 |
| Home addition (family room / kitchen extension) | $220,000 – $380,000 |
| Home addition (second story) | $300,000 – $500,000 |
| Electrical panel upgrade (100A → 200A) | $3,500 – $6,000 |
| Mini-split HVAC for ADU | $6,000 – $14,000 |
What pushes a West Hills price up faster than anything else is the lot itself. A hillside parcel north of Roscoe needs grading and retaining, and a 1960s home with original cast iron plumbing and a 100-amp panel needs utility work before framing can start. We give every family a written price before work begins, and that price does not change unless you change the scope, in writing, first.
Neighborhoods We Serve in West Hills
We work throughout West Hills, from the flat ranch tracts south of Roscoe Blvd to the hillside streets up against the Santa Susana Mountains. Our crews are familiar with the specific permit and terrain issues in each part of the community.
- West Hills Knolls
- Valley Circle Estates
- Capistrano Estates
- Sherwood Forest area
- Hillside lots north of Roscoe Blvd
We typically respond to new estimate requests in West Hills within one business day, and a live person answers the phone around the clock during an active build.
Service Area – Cities Near West Hills
While this page covers West Hills specifically, our ADU and home addition work extends into the surrounding western San Fernando Valley and nearby communities. If you’re in a neighboring city, the conditions change, sometimes a lot, and we have pages for each of those areas: Canoga Park, CA, Calabasas, CA, Chatsworth, CA, and Topanga, CA.
Serving West Hills, CA - Our Local Coverage Area
We’re based in the West Hills 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 West Hills
We can usually schedule a site visit in West Hills within a few business days. The estimate itself, including the written line-item price, follows within about a week after we walk the property and review your lot’s specific conditions. Call (805) 309-3462 to set a time.
Some West Hills neighborhoods have HOAs with architectural review requirements, while others do not. We will check your property’s specific HOA situation during the estimate and tell you exactly which approvals are needed before any work starts. ADU permitting itself goes through the City of Los Angeles.
Yes, we regularly build on hillside lots north of Roscoe Blvd in West Hills. Those projects require specialized grading, foundation engineering, and often retaining walls that flat-lot builds do not need. We budget for that work up front, so the written price reflects the real conditions on your property. Call (805) 309-3462 for an exact quote, and the estimate is free.
For a free estimate on an ADU, garage conversion, or home addition in West Hills, call (805) 309-3462. Ben Ortega and the Seedling team will give you a written price before any work begins, and every job is covered by the 365-Day Done Right Promise.
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 West Hills Customers Say
"Garage to studio conversion with us living right there. They sealed off the dust, cleaned up daily, and respected our quiet hours. No surprise costs. Beautiful."
- Terrence Boylan"Added a backyard cottage. The team protected our existing landscaping and left the yard clean every evening. Gentle, respectful, and they walked us through each stage calmly."
- Tamara Welsh"Backyard cottage build. For a long project they kept the site remarkably tidy and were respectful of our neighbors and our dog. Swept the driveway every evening."
- Leona Pfeiffer
