ADU Company in San Bernardino, CA
Building an ADU in San Bernardino means working with post-WWII housing stock, extreme summer heat, and active seismic zones that most California contractors never encounter together. We’re Seedling ADU Builders, and our Inland Empire office coordinates crews who serve San Bernardino homeowners daily, from the valley floor to the northern foothills. Every project starts with a written price before any work begins, and every completed job carries our 365-Day Done Right Promise. Call us at (707) 383-5338 to schedule your free estimate.
Why San Bernardino Homes Are Different
San Bernardino sits almost directly atop the convergence of the San Andreas and San Jacinto fault systems. That makes a site-specific foundation assessment mandatory on every ADU project we take here, whether it’s a new detached build or a garage conversion. The existing slab on most mid-century homes was never engineered to current standards, so we almost always find ourselves reinforcing or replacing it, a reality contractors in neighboring cities face far less routinely.
The valley’s thermal profile is equally demanding. Summer temperatures of 108 – 112°F, amplified by basin heat-trapping and Santa Ana winds through the Cajon Pass, mean an ADU without properly sized mini-splits and high-performance wall insulation is simply uninhabitable for months each year. We spec thermal loads well beyond what coastal California designers typically account for.
For homeowners in the northern foothills near Muscoy, Very High Fire Hazard Severity Zone requirements add another layer. Chapter 7A mandates ember-resistant vents, Class A roofing, and ignition-resistant siding, additions that routinely run $10,000 – $18,000 and catch families off guard at permit submittal when the city’s VHFHSZ boundary checker flags their parcel.
Electrically, most homes carry 60- to 100-amp service panels that must be upgraded to support a second dwelling unit. We identify this during our first site visit so it never becomes a mid-project surprise.
Our Main San Bernardino Services
San Bernardino homeowners typically call us for one of three projects. Each has its own dedicated page with detailed pricing and local specifics.
Home Addition Contractor in San Bernardino
A home addition in San Bernardino often means tying new construction to a 1950s or 1960s structure with settling foundations and outdated electrical. We start with a structural assessment that accounts for the local seismic profile, then provide a written price that includes any panel upgrade, foundation tie-in, and HVAC extension before we break ground. Our crews work with quiet tools near bedrooms and respect school-hour schedules for families with kids at home. Home Addition Contractor in San Bernardino
Garage Conversion Contractor in San Bernardino
Garage conversions here are complicated by the same slab issues that affect new ADU builds. Most San Bernardino garages sit on non-engineered pads that won’t qualify as habitable space without reinforcement or replacement. We also check whether the existing electrical panel can handle the additional load of a kitchenette, bathroom, and climate control. Our written quote includes every line item so there’s no change order when the slab needs work. Garage Conversion Contractor in San Bernardino
ADU Builders in San Bernardino
Detached ADUs on San Bernardino’s generous lots, typically 7,000 – 12,000 square feet, rarely need setback variances, but they always need seismic-ready foundations and heat-ready envelopes. We work with prefab and modular brands including Cover, Dvele, and Mighty Buildings, matching the product to your lot’s conditions rather than forcing a one-size-fits-all solution. Every ADU we build in San Bernardino is backed by our 365-Day Done Right Promise in writing. ADU Builders in San Bernardino
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 San Bernardino
We maintain hands-on access to leading ADU brands and materials including Cover, Dvele, Mighty Buildings, Boxabl, Plant Prefab, Tuff Shed, and James Hardie. This means San Bernardino homeowners choose the right product for their lot and budget, not just what we prefer to install. Most brand-specific parts are stocked locally through our Inland Empire supply chain, keeping turnaround times short if a replacement is needed during your project. our brands
Pricing for ADU Company in San Bernardino, CA
| Service | Typical range in San Bernardino |
|---|---|
| Foundation assessment and seismic retrofit | $4,500 – $12,000 |
| Slab replacement (garage or ADU pad) | $8,000 – $18,000 |
| Electrical panel upgrade (100A to 200A) | $3,200 – $6,500 |
| Mini-split HVAC system (properly sized for valley heat) | $5,500 – $11,000 |
| Chapter 7A fire-hardening package (VHFHSZ zones) | $10,000 – $18,000 |
| Detached prefab ADU (installed, foundation to finish) | $185,000 – $340,000 |
| Garage conversion (full, including slab and utilities) | $85,000 – $165,000 |
| Home addition (per square foot, mid-grade finish) | $280 – $420 |
| Permit and plan-check fees (city of San Bernardino) | $4,000 – $9,500 |
What pushes San Bernardino prices higher: foundation work on non-engineered slabs, electrical upgrades on older homes, and fire-hardening requirements in VHFHSZ areas. What doesn’t change: your written price, delivered before any work starts, with no surprise line items added after crews arrive.
Neighborhoods We Serve in San Bernardino
Our crews work across the city, from the historic downtown corridor to the foothill edges. Dispatch and scheduling are coordinated from our Inland Empire office, with typical response for initial consultations within a few days across all areas.
- Muscoy
- Arrowhead
- Del Rosa
- Verdemont
- Mount Vernon
Service Area – Cities Near San Bernardino
We regularly drive to projects in surrounding communities where homeowners face similar Inland Empire conditions. If you’re near San Bernardino, we likely serve your area: Loma Linda, CA, Highland, CA, Rialto, CA, and Colton, CA are all within our normal service radius, with the same written-pricing and 365-Day Done Right Promise on every job.
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 Company in San Bernardino
Yes. We handle permit submission, plan check, and inspection scheduling with the city of San Bernardino for every project. This includes VHFHSZ boundary verification and any Chapter 7A fire-hardening requirements that apply to your specific parcel. Call (707) 383-5338 and we’ll confirm what’s needed for your lot during your free estimate.
Plan check typically runs 8 – 14 weeks for a standard ADU or garage conversion, longer if VHFHSZ requirements trigger additional review. We submit complete packages to avoid the resubmission delays that stretch timelines. Our live-answer phone line keeps you updated throughout, never voicemail trees.
California law limits HOA prohibitions on ADUs, but some San Bernardino-area associations still impose design guidelines or parking requirements that affect your project. We review your CC&Rs during our first consultation and flag any conflicts before you invest in plans. Call (707) 383-5338 to schedule that review.
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 San Bernardino Customers Say
"Garage conversion into a studio. They sealed off the work area so dust didn't get into the house, and cleaned up every day before leaving. Calm, careful team to have around."
- Darnell Hobbs"Added a backyard cottage. The team protected our existing landscaping and left the yard clean every evening. Gentle, respectful, and they walked us through each stage calmly."
- Tamara Welsh"Garage to studio conversion with us living right there. They sealed off the dust, cleaned up daily, and respected our quiet hours. No surprise costs. Beautiful."
- Terrence Boylan