A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateADU Company in Corona, CA
Fielding ADU Builders handles ADU construction, garage conversions, and room additions in Corona, CA with a written price before any work starts and a one-year written guarantee on every project. Corona’s mix of 1950s-1990s tract housing, hillside lots south of the 91, and newer developments in the foothills means every job here has its own setbacks, soil, and HOA realities. We match the right build method to your lot and budget, whether that’s a prefab ADU, a conventional build, or a garage conversion. Call (361) 315-4177 to talk through your property.
Why Corona Homes Are Different
Corona sits in a valley that gets real heat in summer, and that heat shapes how we approach every ADU and addition. Attic ventilation, insulation levels, and window placement aren’t afterthoughts here; they determine whether a converted garage or backyard unit stays livable in August. Many homes in central Corona were built between the 1950s and 1980s, which means roof pitch, slab condition, and existing electrical service often need attention before framing begins. Hillside lots in neighborhoods like Sierra del Oro and Eagle Glen add foundation and drainage work that flat-lot builds don’t require.
Permits go through the City of Corona, and the city enforces its ADU setback and height rules carefully. Some HOA communities, particularly around Dos Lagos and The Retreat, have their own design-review boards that run alongside city permitting. We handle plan submission, corrections, and inspection scheduling as part of every job, so you’re not chasing paperwork between the city and your HOA. The soil in much of Corona is decomposed granite, which generally drains well but can shift on steeper grades. That’s why we verify foundation plans and drainage paths before we price anything.
Our Main Corona Services
Corona homeowners most often call us about the same two things: adding square footage to the house they’re in, or turning a garage into rentable or family living space. Each of these has its own dedicated Corona page below.
Room Addition Contractor in Corona
Room additions in Corona usually mean going out into a backyard or up over an existing single-story footprint. The older the house, the more likely we’re reworking roof transitions and upgrading the electrical panel to handle the added load. Corona’s summer heat drives HVAC sizing, so we confirm unit capacity before we frame. Room Addition Contractor in Corona
Garage Conversion Contractor in Corona
Garage conversions in Corona are often the fastest path to an extra bedroom, home office, or rental unit, but they only work when the slab, walls, and roof are sound. Many Corona garages from the 70s and 80s have flatwork that needs leveling and doors that need replacing with properly insulated walls. Garage Conversion Contractor in Corona
ADU Builders in Corona
ADU builds in Corona range from detached backyard units to attached conversions, and the right approach depends on your lot size, setbacks, and how quickly you want it done. We work with prefab platforms like Cover and Dvele for faster timelines, and we also do conventional stick-built ADUs where the lot calls for it. ADU Builders in Corona
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 Corona
We work with leading prefab and modular ADU platforms including Cover, Dvele, Mighty Buildings, and Boxabl, plus conventional construction using James Hardie siding and Tuff Shed-style structures. Parts for these builds are ordered direct from the manufacturers and staged locally in the Inland Empire, which keeps lead times predictable. See our brands for the full list of platforms we’re set up to install.
Pricing for ADU Company in Corona, CA
| Service | Typical range in Corona |
|---|---|
| Custom home addition | $110,000 – $250,000+ |
| Primary suite addition | $70,000 – $140,000 |
| Second-story addition | $120,000 – $250,000+ |
| Bathroom addition | $35,000 – $80,000 |
| Bedroom addition | $30,000 – $75,000 |
| Kitchen extension | $55,000 – $130,000 |
| Bump-out addition | $45,000 – $90,000 |
| Garage conversion | $40,000 – $85,000 |
| Detached ADU (studio – 2BR) | $95,000 – $220,000 |
| Garage ADU conversion | $60,000 – $120,000 |
| Prefab ADU | $85,000 – $190,000 |
| Room addition above garage | $90,000 – $180,000 |
Hillside foundations, HOA design review, and older electrical panels push Corona projects toward the upper end of these ranges. Whatever the number, it goes in writing before any work starts, and that’s the number on the final invoice.
Neighborhoods We Serve in Corona
We work across Corona, from the older central grid near downtown to the foothill communities off the 15 and the master-planned pockets near the 91. Response time for estimates across the city is generally a few business days, depending on how many jobs are in flight.
- Sierra del Oro
- Eagle Glen
- Dos Lagos
- The Retreat
- Downtown Corona
Service Area – Cities Near Corona
Our crews serve Corona and the surrounding cities from our Inland Empire office. We also work in Norco, CA, Chino, CA, Chino Hills, CA, and Irvine, CA. If your project sits near the city line, call and we’ll confirm coverage.
Serving Corona, CA - Our Local Coverage Area
We’re based in the Corona 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 Corona
Once plans are approved and permits are pulled, most Corona ADUs and additions move to framing within a few weeks. The schedule depends on plan review at the City of Corona and whether your HOA has a design-review step. We’ll give you a written timeline when we quote the job.
Yes. We prepare and submit drawings to the City of Corona, manage corrections, and coordinate inspection scheduling. If your community has an HOA design-review process, we’ll prepare the submittal package they require, so you’re not stuck between the city and the board.
No. The price in your written quote is the price on the final invoice, unless you ask us to add scope. We give you a line-item price before any work begins, and The Garrison Standard backs the workmanship in writing for a full year. Call (361) 315-4177 for a free estimate.
Call (361) 315-4177 to schedule a free estimate for your ADU, addition, or garage conversion in Corona, CA.
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 Corona 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.
