A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateADU Company in Castaic, CA
Fielding ADU Builders plans, prices, and builds accessory dwelling units, garage conversions, and room additions in Castaic, CA. Castaic jobs run differently than work closer to the LA basin: lots are larger, summer heat hits harder, and the Santa Clarita Valley’s hillside soils shape how we handle foundations and drainage. This page covers how we approach ADU work in Castaic, what things cost here, and the neighborhoods we serve. Call (361) 315-4177 and a live person answers, day or night.
Why Castaic Homes Are Different
Homes in Castaic were built across a wide stretch of decades, which means we see everything from 1970s ranchers to newer subdivisions near Castaic Lake and Hasley Canyon. That spread changes the work. Older homes often carry electrical panels sized for a single family’s 1980s load, so an ADU or a garage conversion can mean a panel upgrade before the wall framing starts. Terrain matters too: many parcels in Castaic sit on sloped lots, and some homes are close enough to the lake or to Castaic Creek that drainage and setback rules get stricter. We work those details into the written price before the first permit is pulled.
Heat is the other Castaic factor. Summer temperatures routinely pass 100 degrees in this part of the Santa Clarita Valley, so we schedule exterior work in the early morning and choose materials that hold up under direct sun. Insulation and window placement get more attention here than in coastal cities. The upshot is simple: an ADU company that knows Castaic will price for the lot, the panel, and the climate from the start, not discover them after framing begins.
Our Main Castaic Services
Three jobs dominate the calls we take from Castaic homeowners: adding a room, converting a garage, and building a detached ADU. Each has its own Castaic page with pricing and scope. Here is what each one actually involves in this city.
Room Addition Contractor in Castaic
A room addition in Castaic usually means extending a single-story home outward into a large backyard, or building a second-story bump-out on a hillside lot. We pull permits through Los Angeles County, handle the structural engineering for slope-adjacent footings, and match exterior materials to the existing house so the addition does not look bolted on. Many Castaic additions also require a drain plan update because of how runoff moves on sloped parcels. For a full breakdown of pricing and schedule, see our Room Addition Contractor in Castaic page.
Garage Conversion Contractor in Castaic
Castaic’s two-car and three-car garages are among the least expensive ways to add livable square feet, but the job is not just drywall and paint. Older Castaic garages often lack a moisture barrier under the slab, so we test and fix that before flooring goes down. Insulation, electrical service, and egress windows all get pulled into the plan. The price goes in writing before work starts, and the one-year written guarantee covers what gets built. Details are on our Garage Conversion Contractor in Castaic page.
ADU Builders in Castaic
Detached ADUs in Castaic work well on the city’s larger lots, where a backyard unit can be built without crowding the main house. We build conventional stick-frame ADUs and we work with prefab platforms like Cover and Dvele when the lot and budget favor factory-built panels. Setback rules, fire-safety requirements, and utility trenching for detached units all shape the final price. We put that number in writing before anything gets ordered. See our ADU Builders in Castaic page for typical ranges and timelines.
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 Castaic
We build with and service the ADU and modular platforms Castaic homeowners ask about most. That includes Cover, Dvele, and Mighty Buildings for prefab units, plus conventional builds with James Hardie siding. See our brands for parts availability and the full list of platforms we work with.
Pricing for ADU Company in Castaic, CA
| Service | Typical range in Castaic |
|---|---|
| Detached ADU (prefab, 400 – 600 sq ft) | $120,000 – $220,000 |
| Detached ADU (conventional build, 600 – 800 sq ft) | $180,000 – $350,000 |
| Garage conversion (400 sq ft, finished) | $85,000 – $150,000 |
| Garage conversion (600 sq ft, with bathroom) | $110,000 – $190,000 |
| Room addition (300 sq ft, single story) | $90,000 – $160,000 |
| Room addition (500 sq ft, with bathroom) | $150,000 – $260,000 |
| Electrical panel upgrade (when required) | $3,500 – $6,500 |
| Site prep and drainage work (sloped lots) | $8,000 – $25,000 |
Prices in Castaic climb when we are working a sloped lot that needs retaining or extra drainage, when the existing electrical panel must be replaced, or when the site sits in a fire-hazard zone that requires specific siding and venting. Those are real costs, not change orders. Garrison Partners writes the price before any work starts, so the number you approve at the start is the number on the final invoice.
Neighborhoods We Serve in Castaic
We work across Castaic and the surrounding communities, from the lake side of town through the hillside developments. Scheduling runs on a single queue, so your written estimate comes first and the work starts on the date we agree to.
- Hasley Canyon
- Northlake
- Hillcrest
- Val Verde
- Castaic Lake area
Service Area – Cities Near Castaic
Our crews serve Castaic and the neighboring Santa Clarita Valley communities. If your property is in Valencia, CA, Stevenson Ranch, CA, Santa Clarita, CA, or Newhall, CA, the same written-price process and one-year guarantee apply. Dispatch and scheduling are coordinated from the brand’s Los Angeles office; crews serve Castaic locally.
Serving Castaic, CA - Our Local Coverage Area
We’re based in the Castaic 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 Castaic
Sloped lots, older electrical panels, and summer heat all affect how we plan and price ADU work in Castaic. Drainage and fire-zone requirements also come up more often here than inland. We fold those into the written estimate upfront, not after framing starts. Call (361) 315-4177 to get a project-specific quote.
Yes. Castaic is unincorporated Los Angeles County, so ADUs, garage conversions, and room additions require county permits and inspections. We pull all permits, schedule inspections, and keep the permit card on site until final sign-off. It is part of the written price.
Once we agree on scope and price, scheduling depends on permit turnaround and the queue at the time. We do not start without an approved permit, and we do not move the start date silently. Call (361) 315-4177 for current scheduling and a free written estimate.
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 Castaic Customers Say
"Solid job. Cabinet delivery was a week behind but they worked around it."
- Ben G."Insulation, drywall, and finishes were all well done. Feels like part of the house."
- Pete O."Built a detached ADU behind our house. The builder is a veteran and runs the site like a platoon: schedule posted, crew on time, everything labeled. Finished within a few days of the date."
- Ken W.
