A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateADU Company in Fontana, CA
ADU work in Fontana, CA comes with its own set of realities: large lots cut from former citrus and dairy land, a hot inland climate that punishes cheap materials, and a city building department that expects plans to be right the first time. Fielding ADU Builders handles garage conversions, backyard ADUs, and room additions as an independently owned member of the Garrison Partners family, which has built to The Garrison Standard since 2006. Every Fontana project gets a written price before any work starts, a permitted build, and a one-year written guarantee. Call (361) 315-4177 to schedule a free estimate.
Why Fontana Homes Are Different
Fontana’s housing stock trends newer than many Inland Empire cities: much of the north side, in neighborhoods like Hunter’s Ridge and Sierra Lakes, was built in the 1990s and 2000s, while the older districts south of Foothill Boulevard and along Arrow Boulevard date back to the postwar boom. That split matters for ADU work. Newer tract homes usually sit on compact lots with engineered trusses and stucco exteriors, which changes how we tie a room addition into the roofline. Older homes are often wood-framed and easier to modify at the framing stage, but they carry the added steps of reworking electrical panels and verifying foundation integrity before we push for permits.
The climate is the other driver. Fontana sees summer stretches above 100 degrees, and that means insulation, HVAC sizing, and window placement are not afterthoughts on an ADU. We spec roofs and wall assemblies expecting real heat loading, not coastal assumptions. A garage conversion in Fontana without a serious cooling plan is a room that gets used three months a year. We design for year-round occupancy from the start, and we price it that way too.
Our Main Fontana Services
Most Fontana homeowners reach out to us for one of three reasons: they need more living space but don’t want to move, a garage is sitting unused, or they want rental income from a backyard unit. Each service has its own detailed Fontana page linked below.
Room Addition Contractor in Fontana
A room addition in Fontana means tying new square footage into an existing slab or raised foundation, matching stucco or siding, and extending the roofline so the addition doesn’t read as an afterthought. On lots in areas like Southridge or the older blocks near Juniper Avenue, the biggest variable is set back variance, the city’s written permission to build closer to the property line than the standard rule allows. We handle the variance paperwork as part of the permit package, and the written price covers drawings, engineering, and construction. Reed Calloway oversees every Fontana addition from first measurement to final walkthrough. Learn more on our Room Addition Contractor in Fontana page.
Garage Conversion Contractor in Fontana
Fontana garages convert differently depending on the era. Older attached garages on standard 20-by-20 footprints convert easily into one-bedroom units, but many newer homes have tandem garages requiring more creative floor plans. Our garage conversions replace the door with a framed wall, bring the slab up to living-space standards, and add insulation, drywall, lighting, and a proper HVAC feed. Fontana’s summer heat makes insulation and a dedicated cooling line non-negotiable, and that work is included in the price you approve up front. Details are on our Garage Conversion Contractor in Fontana page.
ADU Builders in Fontana
Backyard ADUs in Fontana follow California state law for minimum sizes and setbacks, but the city adds its own plan check, utility connection requirements, and inspection schedule. We build detached units in backyards across Fontana, from the large lots near Summit Avenue to the tighter parcels west of the 15. We match the build method to the lot and budget, including prefab and modular systems from Cover, Dvele, and Mighty Buildings where they fit, and conventional construction with James Hardie siding where they don’t. See the full scope on our ADU Builders in Fontana 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 Fontana
We install and service ADU structures from Cover, Dvele, and Mighty Buildings, and we build conventional units with James Hardie siding. Common replacement parts and finish materials stay stocked at our Inland Empire supply runs, so most Fontana jobs don’t wait on back-ordered components. See our brands for the full list of platforms we work with.
Pricing for ADU Company in Fontana, CA
| Service | Typical range in Fontana |
|---|---|
| Garage conversion, attached, to code | $85,000 – $145,000 |
| Detached one-bedroom ADU, conventional build | $180,000 – $260,000 |
| Detached two-bedroom ADU, conventional build | $240,000 – $340,000 |
| Prefab ADU, turnkey (Cover, Dvele, or Mighty Buildings) | $190,000 – $310,000 |
| Primary suite addition | $120,000 – $190,000 |
| Second-story room addition | $200,000 – $320,000 |
| Kitchen expansion or bump-out | $70,000 – $120,000 |
| Foundation work, retrofit or repair | $12,000 – $40,000 |
| Electrical service upgrade, 200A panel | $4,500 – $8,500 |
| HVAC rough-in for a converted garage | $7,000 – $14,000 |
Prices in Fontana move on two things: the condition of the existing structure and the lot’s access for equipment and materials. A garage conversion on a 1960s slab with outdated wiring runs higher than one on a 2005 track home, and a backyard ADU at the rear of a deep lot with narrow side access costs more than one with a straight shot from the street.
Whatever the number, it goes in writing before we start. The price you approve on day one is the price on the final invoice, no change orders, no door surprises.
Neighborhoods We Serve in Fontana
We work across all of Fontana, from the newer subdivisions on the north side to the established blocks near downtown. Scheduling is handled from our Inland Empire office, so crews arrive for estimates and construction without a long dispatch chain. Neighborhoods we regularly build in include:
- Sierra Lakes
- Hunter’s Ridge
- Southridge
- Walnut Village
- Downtown Fontana
Response time for an estimate across Fontana is typically a few business days, depending on how many permits we’re pulling elsewhere in the city that week.
Service Area – Cities Near Fontana
Fielding ADU Builders serves Fontana and the surrounding cities from our Inland Empire office. If you’re in Bloomington, CA, Rialto, CA, Rancho Cucamonga, CA, or Riverside, CA, we handle ADUs, garage conversions, and room additions with the same written-price-first policy and one-year guarantee.
Serving Fontana, CA - Our Local Coverage Area
We’re based in the Fontana 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 Fontana
We schedule estimates across Fontana within a few business days. Calls are answered by a live person around the clock, so you’ll speak to someone directly when you call (361) 315-4177. From there we set a visit time that matches your schedule.
Every ADU, garage conversion, and room addition in Fontana requires a city permit and inspections. We pull the permits for you and coordinate the inspections through the city’s process. This is not optional work, skipping permits creates a compliance problem at sale and voids our one-year written guarantee. Call (361) 315-4177 for a free estimate that includes permit handling.
Our service area covers all of Fontana, plus Bloomington, Rialto, Rancho Cucamonga, and Riverside. We schedule construction from our Inland Empire office, with crews that service Fontana locally rather than driving in from out of the region. Call (361) 315-4177 to confirm your address is in our service area and get a free 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 Fontana Customers Say
"Room addition over the back patio. Framing is square, windows are tight, and the roofline matches."
- Danny L."Foundation and slab poured on schedule. Crew kept the yard orderly."
- Marian J."Garage conversion with a new bath and kitchenette. Permit was handled by them. Inspection passed first time."
- Sheila B.
