BOSS Homes ADUs for San Bernardino County
San Bernardino County is the largest county in the United States by area, and the distance from one end of it to the other is longer than some states. What that means in practice for an ADU is that where your property sits determines a great deal about how the project runs.
We manufacture in Montebello, hold the contract, and assemble with our own crew. One company, one point of accountability.
LOCAL RULES
What you can build in San Bernardino County
The state framework applies here exactly as it does everywhere else in California. No jurisdiction can require more than four feet from your side and rear property lines. None can impose a minimum lot size or require you to live on the property. A compliant application must be approved ministerially, on objective standards, without a hearing. And you are protected in building at least 800 square feet regardless of local coverage rules.
The variable here is which agency. The county contains two dozen incorporated cities, and a large share of its population lives in unincorporated territory served directly by San Bernardino County Land Use Services. A homeowner in Rancho Cucamonga, a homeowner in Victorville and a homeowner in an unincorporated stretch of the valley are following the same state rules through three different offices with three different fee schedules.
Lots here are generally larger than anywhere else we build, which usually means the constraint on your project is budget rather than space. That is a different conversation from the one we have closer to the coast, and it changes which model makes sense.
Fire matters here more than in most of the region. Large areas of the county, particularly through the foothills and the mountain communities, fall inside designated fire hazard severity zones. Our panels are light gauge steel framing around a PIR insulation core, finished with cement board outside and drywall inside. The assembly carries an ASTM E84 Class A fire rating and meets Wildland Urban Interface requirements, which is worth weighing against a stick framed unit on the same parcel.
Distance and site access
We should be straight about geography. The western valley is a routine delivery from our Montebello factory. The high desert and the mountain communities are further out, and we would want to look at site access before quoting rather than after.
WHAT WE BUILD
ADUs for San Bernardino County lots
Eight models, studio through three bedroom. With the lot sizes out here, the whole range is usually workable.
Two and three bedroom, 750 to 1,200 sq ft
Rendering. Two Bed Core, 20' x 40'.
BEST FOR: THE SPACE THIS COUNTY GIVES YOU
Rear yards in Fontana, Rialto, Redlands and the unincorporated valley are among the deepest we build on, and a 20 by 40 foot two bedroom or a 30 by 40 foot three bedroom will often sit comfortably without touching the setbacks. Where the space exists, the larger models are the better value per square foot and the more useful building at the end of it.
- Three two bedroom layouts, one three bedroom
- Two full bathrooms on most configurations
- From $228,395 installed, including civil work and assembly
One bedroom, 360 to 500 sq ft
Rendering. One Bed Plus, 16' x 32'.
BEST FOR: MULTIGENERATIONAL HOUSEHOLDS
A separate bedroom with its own bathroom is what makes a unit work for a parent or an adult child long term rather than as a temporary arrangement. On the standard valley lot there is room for a 16 by 32 foot unit without losing the yard.
- One Bed Core at 16′ x 24′, One Bed Plus at 16′ x 32′
- Separate bedroom, full bath, walk-in closet on the Plus
- From $142,495 installed, including civil work and assembly
Studios, 220 to 320 sq ft
Rendering. Studio Core, 10' x 24'.
BEST FOR: THE SHORTEST PATH TO A FINISHED UNIT
When the priority is budget and speed rather than square footage, the studio is the model that gets there. It carries a full kitchen and bathroom, and at 220 to 320 square feet it fits on parcels where a larger unit would run into a well, a septic field or a slope.
- Studio Core at 10′ x 24′, Studio Plus at 12′ x 28′
- Full bathroom and kitchen in both
- From $110,695 installed, including civil work and assembly
HOW IT IS BUILT
Seven trades, one panel
Our wall and roof panels are manufactured in Montebello with framing, sheathing, insulation and the electrical and plumbing rough-ins already integrated. Light gauge steel framing around a PIR insulation core, cement board outside, drywall inside, so the finished room feels like any other room in your house. Your panels are being built in the factory while your foundation and utilities go in on site, rather than one after the other. ASTM E84 Class A fire rating, meets Wildland Urban Interface requirements, evaluated under IAPMO UES ER-0658.
WHAT PEOPLE SAY
Homeowners, cities and builders
Overall we had an amazing experience working with BOSS. Delivery deadline was met to avoid any delays with our project deadline, with very detailed direction in regard to assembly.
Bernardo Navarrete, City of Baldwin Park
I’m glad I chose BOSS Homes for my tiny house. They delivered a high-quality product at a fair price, and their team was knowledgeable, responsive, and easy to work with.
Paul Meredith, Homeowner
The BOSS system has been intelligently and strategically designed so the site assembly was remarkably simple.
Michael Waters, Swinerton Builders
Areas we serve
We serve San Bernardino and the surrounding county, including Fontana, Rancho Cucamonga, Ontario, Rialto, Chino, Chino Hills, Upland, Redlands, Colton, Yucaipa, Montclair, Highland, Loma Linda, Grand Terrace and the unincorporated areas of the western valley.
Questions
Common questions in San Bernardino County
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Who issues my ADU permit in San Bernardino County?
Either your city or, if your property is in unincorporated territory, San Bernardino County Land Use Services. A large share of the county population is in unincorporated areas, so this is worth confirming first.
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Do I have more room to build out here?
Generally yes. Lots in this county tend to be the largest we build on, which often makes a two or three bedroom unit practical where it would not be closer in.
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Do you deliver to the high desert and the mountains?
We would want to look at site access before committing. The western valley is a routine delivery from Montebello.
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What about fire zones?
Substantial parts of the county are in fire hazard severity zones, which carry extra building requirements. Our panels carry an ASTM E84 Class A fire rating and meet Wildland Urban Interface requirements. We confirm exactly what applies to your parcel during the feasibility study.
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Can I rent the ADU out?
Yes, for terms of thirty days or longer. Owner occupancy requirements for standard ADUs have been permanently removed under state law.
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How do I find out what fits on my lot?
Our feasibility study produces a site plan with placement options, a setback and zoning analysis and the maximum allowable size for your property. It is $1,000 and refundable.
No cost, no obligation
See what fits on your lot
Tell us where the property is and we will call you back to talk through what is possible.
Or call us now on 1-888-634-0338
