A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateFast, Reliable ADU Builders Across San Bernardino
Adding a second home to your San Bernardino lot usually costs between $140,000 and $320,000 for a detached unit, and the city’s permit path runs through Development Services under the 2020 California code cycle. That’s the real number, before anyone steps foot on your property. Sutton ADU Builders has been building accessory dwelling units since 2006, and our crews know exactly how San Bernardino’s foothill fire-zone review, soil conditions, and setback rules shape every project. If you’re pricing a detached ADU or converting interior square footage into a JADU, call (472) 248-8213 and we’ll give you a written price before any work starts.
Why Sutton ADU Builders Is San Bernardino’s Preferred ADU Builders Company
San Bernardino homeowners don’t need a builder who talks in generalities. They need someone who knows that a lot off Kendall Drive near Cal State faces different plan-check scrutiny than a flat parcel off Base Line, and that the difference changes your material costs. Our ADU Builders team has walked dozens of San Bernardino properties through the Development Services process, and we quote each one with the actual site conditions in mind, not a statewide template.
Every Sutton project runs on the Threshold Standard. That means every person who arrives at your door has been background-checked, identity-verified, and photo-badged. Their name and photo are sent to you before the visit. Miles Hartwell, our owner, set that policy in 2006 and has never loosened it. If a homeowner in Del Rosa or Verdemont is home alone when the crew arrives, they already know exactly who they’re opening the door to.
Our written price is locked before a single tool is lifted. The 365-Day Done Right Promise covers defects in workmanship for one full calendar year from project completion. If something isn’t right, we come back and make it right. No haggling, no fee. That’s the whole point of the Threshold Standard.
Detached ADU in San Bernardino
A detached ADU in San Bernardino is a separate structure on your property, built from the ground up, with its own foundation, walls, roof, and utility connections. This is the right move when you have a large lot, want rental income from a fully independent unit, or need space for an adult child or aging parent that doesn’t share walls with the main house. Most detached ADUs in San Bernardino run $180,000 to $320,000 depending on size, site conditions, and finish level. A 600-square-foot one-bedroom is the most common build we do, and a two-bedroom around 800 to 1,000 square feet lands at the upper end of that range.
Foundation and Soils Work
San Bernardino’s foothill soils, especially along the Del Rosa and Verdemont corridors, can require deeper footing embedment than the flat central city. The city inspector will check this, and a footing that doesn’t meet the deeper embedment standard fails. We plan for it from the first site visit, so the price you get doesn’t change when the inspector arrives.
Panelized and Factory-Built ADUs
Pre-approved plans from Abodu, Cover, or Mighty Buildings can shorten design time, but they still have to clear San Bernardino site, setback, and utility review on your specific parcel. We’ve set panelized units on corner lots and through-lots across the city, and we handle the plan-check coordination so you don’t get stuck in back-and-forth with the permitting desk.
JADU in San Bernardino
A JADU in San Bernardino converts existing square footage inside your primary house into a small independent unit, usually a studio or one-bedroom under 500 square feet, often from a spare bedroom, an enclosed porch, or a section of the garage that’s already within the home’s footprint. This is the lower-cost path, typically $60,000 to $140,000, and it’s governed by a different rule than a detached ADU: the conversion has to use space that already exists inside the primary dwelling. You can’t add a JADU as a new stand-alone structure.
Interior Conversion Requirements
The city’s JADU path requires the unit to share at least one utility connection with the main house, and it can share a bathroom. That’s what keeps the permit fees and construction costs lower than a detached build. San Bernardino homeowners often choose this when they want a rental unit or in-law space but don’t have the lot room for a separate structure.
Where JADUs Get Misquoted
We see quotes from other builders that treat a JADU like a mini detached ADU, with separate utility runs and new exterior walls. That misses the point of the existing-footprint requirement and inflates the price. If you’re being quoted over $140,000 for a JADU in San Bernardino, you’re likely being priced for a detached ADU with the wrong permit path. We’ll give you the honest number based on what your house actually has.
Trusted Brands We Service in San Bernardino
Sutton ADU Builders has direct experience with Abodu panelized units, Dvele high-performance modular homes, and Mighty Buildings factory-built ADUs. That matters in San Bernardino because each brand has a different plan-set style, foundation requirement, and utility connection detail, and the city’s Development Services reviewers treat each one differently. We stock local materials and coordinate delivery so a panelized unit doesn’t sit on your lot waiting for a missing connection detail. Whether you’ve already bought a plan or you’re still deciding between a custom build and a factory unit, we’ll walk you through which product line fits your lot, your budget, and the city’s review path.
Common ADU Builders Problems We See in San Bernardino Homes
- Skipping the fire-hazard check before quoting. San Bernardino sits in a declared Very High Fire Hazard Severity Zone corridor along the foothills. Decks, roofing, and exterior materials that pass in the flat city can fail plan check in the Del Rosa or Verdemont areas. We confirm your lot’s designation before we price anything.
- Pricing a JADU like a new build. A JADU has to convert existing interior square footage. If a quote treats it as a separate structure with new exterior walls and independent utilities, the number is wrong. The permit path is different, and the price should be too.
- Assuming a factory plan skips local review. A pre-approved or panelized plan from Boxabl, Plant Prefab, or Mighty Buildings still has to clear San Bernardino site, setback, and utility review. The city checks your parcel, not just the factory’s drawings. We handle that review so there are no surprises at plan check.
- Footing depth failure in foothill soils. On a corner lot in the Del Rosa area, our crew set a 600-square-foot detached ADU built to a plan set our client bought through Abodu, and we had to re-pour the footing after the city inspector flagged the original one for not meeting the deeper embedment the San Bernardino foothill soils require. We walked the foundation, framing, and final inspections through Development Services and handed over a finished unit with James Hardie siding, a full kitchen, and its own 100-amp electric service. That’s what proper scoping avoids.
Pricing for ADU Builders in San Bernardino, CA
Here are honest ranges for the San Bernardino market, not statewide averages. A detached ADU built from the ground up runs $180,000 to $320,000 for a 600 to 1,000 square foot unit. A JADU conversion inside your existing home runs $60,000 to $140,000. A panelized or factory-built ADU from Abodu, Cover, or Dvele typically lands between $160,000 and $280,000 including site work, foundation, and utility connections. A garage conversion that stays within the existing structure runs $90,000 to $180,000. What changes the price: your lot’s fire-hazard designation, soil conditions, utility panel capacity, and whether the city requires deeper footings. Call (472) 248-8213 for a written estimate based on your specific property. The estimate is free, and it’s a fixed number, not a placeholder.
We Also Serve Cities Near San Bernardino
Our crews serve ADU Builders in San Bernardino and the surrounding Inland Empire communities, including Loma Linda, Highland, Rialto, and Colton. If your property sits near the city line or you’re planning an ADU on a lot in one of those neighboring cities, we’ll scope it with the same written-price, Threshold Verified standard. The permit paths and fire-zone rules differ slightly from city to city, and we know each one.
Serving San Bernardino, CA - Our Local Coverage Area
We’re based in the San Bernardino 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 Builders in San Bernardino
Yes. San Bernardino sits in a declared Very High Fire Hazard Severity Zone corridor along the foothills, and any ADU in the Del Rosa, Verdemont, or other foothill-adjacent areas will have its exterior materials, roofing, and decks reviewed under those standards. Plan check will flag materials that don’t meet the zone’s requirements. Call (472) 248-8213 and we’ll confirm your lot’s designation before we quote, so the price you get is the price that holds.
A detached ADU is a separate structure built from the ground up on your lot, usually 600 to 1,000 square feet, with its own foundation and utility connections, running $180,000 to $320,000 in San Bernardino. A JADU converts existing square footage inside your primary house, under 500 square feet, sharing at least one utility, running $60,000 to $140,000. The permit path is different, the cost is different, and the city’s requirements are different. Call (472) 248-8213 and we’ll tell you which one your lot and house actually support.
Yes, you still need local permits. A pre-approved plan from Abodu, Cover, Mighty Buildings, or Boxabl shortens design time, but the ADU still has to clear San Bernardino site, setback, and utility-connection review on your specific parcel. The city reviews your lot, not just the factory drawings. We coordinate that review and keep the plan-check process moving. Call (472) 248-8213 for a written estimate that includes local permit coordination.
You’ll go through foundation and footing inspection, framing inspection, rough electrical and plumbing, insulation, and final building inspection. San Bernardino’s Development Services also verifies compliance with the fire-hazard zone requirements if your lot is in a foothill-adjacent area. Each inspection has to pass before the next phase starts, and we schedule and manage every one. Call (472) 248-8213 and we’ll walk you through the full inspection calendar for your specific build.
The most common cost adders in San Bernardino are deeper footing embedment required by foothill soils, fire-resistant exterior materials required by the fire-hazard zone, and utility panel upgrades if your existing electrical service can’t handle the additional load. These should be identified during scoping, not after the work starts. Our written price locks in the scope we agree on, and if something changes, you approve it before we proceed. Call (472) 248-8213 to get a fixed price based on your actual property conditions.
Adding an ADU to your San Bernardino property is a settled, rooted decision. Sutton, an old English name for a south farm, fits exactly that. You’re planting a second home on land you already own. We’ll give you a written price, a named crew with verified identities, and a 365-day promise that the work is right. Call (472) 248-8213 to schedule your free estimate.
Written by Miles Hartwell, Owner at Sutton ADU Builders, serving San Bernardino since 2006.
