ADU in San Bernardino, CA
Junior ADU and interior conversion projects in San Bernardino typically run $85,000-$155,000 all-in, drawings through final inspection, while site prep and utility work for detached ADUs adds $35,000-$75,000 before construction begins. We’re Ellery ADU Studio, and our Inland Empire office coordinates crews across San Bernardino’s post-war neighborhoods daily. Call (909) 359-6463 to schedule your free estimate.
Why San Bernardino Homes Are Different
San Bernardino sits closer to the San Andreas Fault than almost any other large California city. The fault trace runs along the San Bernardino Mountains through Cajon Pass, which means ADU foundation work here routinely triggers soils reports and special seismic inspections that Riverside or Ontario rarely require.
Most residential neighborhoods were built between 1945 and 1975, with slab-on-grade foundations and 60-100 amp electrical panels that almost always need upgrading before an ADU permit issues. Lots run 7,500-10,000 square feet, many with rear-alley garage access. At 1,050 feet elevation, summer highs exceed 108°F and hard freezes occur in winter, so HVAC and plumbing specs must handle wider swings than coastal builders typically plan for. Northern neighborhoods near Verdemont and the Highland border can fall within fault-proximity study zones requiring a licensed geotechnical engineer’s report before foundation permits release.
Our Main San Bernardino Services
San Bernardino homeowners call us most often for these three project types:
ADU Design & Permitting in San Bernardino
We produce the full permit set, structural calculations, and Title 24 energy compliance as a single deliverable, not a handoff between designer and engineer. In San Bernardino, that means coordinating with the city building department on seismic detailing and, in northern neighborhoods, flagging potential geotechnical triggers early so they don’t stall your permit later. ADU Design & Permitting in San Bernardino covers the complete process from as-built survey to issued permit.
Garage Conversion ADU in San Bernardino
Rear-alley garages in neighborhoods like Arrowview and Del Rosa make this the most common ADU type we build here. We assess slab thickness, roof structure, and whether the existing electrical service can carry the additional load, or if a panel upgrade needs to run in parallel. Garage Conversion ADU in San Bernardino details our full process.
New Detached ADU in San Bernardino
Spacious lots and alley access create ideal conditions for standalone units, but fault-proximity zones in northern areas can add geotechnical costs and timeline. We coordinate soils reports when triggered, spec frost-protected plumbing for the elevation, and handle setback variances with the city directly. New Detached ADU in San Bernardino explains our design-build approach.
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.
Junior ADU & Interior Conversion in San Bernardino
Junior ADU and interior conversion work in San Bernardino solves a specific problem: homeowners who want rental income or multigenerational housing without the cost and complexity of new foundation work in a high-seismic zone. The city’s stock of 1950s-1970s homes with generous floor plans, basement crawl spaces, and attached garages creates natural opportunities for self-contained units that use existing structure. We handle the full Junior ADU & Interior Conversion process, including the separate kitchen and exterior entrance the city requires, under our single design-build contract.
Room-to-ADU Conversion
Signs you need it
An attached bedroom or den with its own exterior door potential and access to existing plumbing stacks can become a self-contained junior ADU with the right permit set.
What it costs in San Bernardino
Room-to-ADU conversions in San Bernardino typically run $85,000-$125,000 all-in, including the separate kitchenette, bathroom rough-in, and permit set.
How we do it
We survey existing structure, produce the junior ADU permit set with fire separation details, coordinate the electrical panel upgrade if needed, and build to the issued drawings under our 365-Day Done Right Promise.
Above-Garage ADU
Signs you need it
A detached garage with adequate foundation and roof structure, particularly in alley-access neighborhoods, can support a second-story junior ADU with separate entrance.
What it costs in San Bernardino
Above-garage ADU construction in San Bernardino typically ranges $110,000-$155,000, including structural reinforcement, stair or exterior access, and full MEP rough-in.
How we do it
We verify load capacity, design the structural upgrade as part of the permit set, and coordinate the work so the garage below remains functional throughout construction.
What Junior ADU & Interior Conversion Costs in San Bernardino
| Item | Typical range in San Bernardino |
|---|---|
| Room-to-ADU conversion (all-in) | $85,000 - $125,000 |
| Above-garage ADU (all-in) | $110,000 - $155,000 |
| Junior ADU permit set and design | $8,500 - $14,000 |
Do I need a separate electrical meter for a junior ADU in San Bernardino?
No, junior ADUs share the primary residence’s meter and service, though most San Bernardino homes need a panel upgrade from 60-100 amps to 200 amps to handle the additional load. Call (909) 359-6463 for an exact quote - estimates are free.
Can I convert my basement to a junior ADU in San Bernardino?
Basement conversions are permitted if the space meets ceiling height, egress, and ventilation requirements; many post-war San Bernardino homes have 7-foot basements that need excavation or creative design solutions. Call (909) 359-6463 for an exact quote - estimates are free.
ADU Site Prep & Utilities in San Bernardino
ADU site prep and utility work in San Bernardino addresses conditions that new construction rarely faces elsewhere: expansive clay soils, seismic settlement risks, and electrical panels from the 1960s that cannot support modern ADU loads. The extreme temperature range here, from 108°F summers to occasional hard freezes, also means utility rough-ins need deeper burial and freeze-protected specifications than coastal California projects. We coordinate all ADU Site Prep & Utilities work under the same single contract as the build, so no subcontractor gaps delay your permit or final inspection.
Electrical Panel Upgrade
Signs you need it
A 60 or 100 amp main panel, common in San Bernardino’s post-war housing stock, cannot carry an ADU’s additional HVAC, kitchen, and laundry circuits.
What it costs in San Bernardino
Electrical panel upgrades in San Bernardino typically run $4,500-$8,500, including the new 200 amp panel, permit, and SCE coordination.
How we do it
We assess load calculations as part of the permit set, schedule Southern California Edison disconnect and reconnect, and pass inspection before rough-in begins.
Foundation & Grading
Signs you need it
New detached ADUs on San Bernardino’s expansive soils, especially in northern fault-proximity zones, require engineered foundations that standard slab-on-grade does not satisfy.
What it costs in San Bernardino
Foundation and grading work in San Bernardino typically ranges $18,000-$35,000 for standard conditions, with geotechnical reports adding $3,500-$6,500 in triggered zones.
How we do it
We flag geotechnical triggers during preliminary survey, engage a licensed engineer when required, and produce the foundation plan as part of the permit set.
What ADU Site Prep & Utilities Costs in San Bernardino
| Item | Typical range in San Bernardino |
|---|---|
| Electrical panel upgrade (200 amp) | $4,500 - $8,500 |
| Foundation and grading (standard) | $18,000 - $35,000 |
| Geotechnical report (if triggered) | $3,500 - $6,500 |
Will my ADU need a separate water meter in San Bernardino?
San Bernardino allows ADUs to share the primary residence’s water service, though a separate meter is optional and sometimes preferred for rental accounting; we coordinate with the San Bernardino Municipal Water Department during permit. Call (909) 359-6463 for an exact quote - estimates are free.
How deep are utility lines buried for ADUs in San Bernardino?
Water and sewer laterals typically require 18-24 inch burial, but we spec 30-36 inches for freeze protection given San Bernardino’s occasional hard freezes and wider temperature swings than coastal areas. Call (909) 359-6463 for an exact quote - estimates are free.
Brands We Service in San Bernardino
We specify and coordinate prefab and modular systems from Dvele, Mighty Buildings, Boxabl, and Plant Prefab within our single design-build contract, with parts and technical support available through our Inland Empire office. Our brands page details each system’s integration process.
Pricing for ADU in San Bernardino, CA
| Service | Typical range in San Bernardino |
|---|---|
| Room-to-ADU conversion (all-in) | $85,000 - $125,000 |
| Above-garage ADU (all-in) | $110,000 - $155,000 |
| Junior ADU permit set and design | $8,500 - $14,000 |
| Electrical panel upgrade (200 amp) | $4,500 - $8,500 |
| Foundation and grading (standard) | $18,000 - $35,000 |
| Geotechnical report (if triggered) | $3,500 - $6,500 |
| Plumbing lateral extension | $6,500 - $12,000 |
| Gas line extension | $3,500 - $7,500 |
In San Bernardino, geotechnical triggers in northern fault-proximity zones and required electrical upgrades push projects toward the higher end of these ranges. Under Haven Standard Clause 1, every project receives a written price before any work begins, with no change orders for scope we’ve already agreed to.
Neighborhoods We Serve in San Bernardino
Our crews work across San Bernardino’s established residential areas, from the older tracts near downtown to the foothill neighborhoods approaching the mountain front. Scheduling and dispatch run from our Inland Empire office, with typical site visits available within two business days.
- Arrowview
- Del Rosa
- Verdemont
- University Hills
- Mount Vernon
Service Area - Cities Near San Bernardino
We coordinate ADU design, permitting, and construction throughout the Inland Empire core, with regular work in Highland, CA, Rialto, CA, Colton, CA, and Grand Terrace, CA. Each city carries its own permit timelines and inspection protocols, which we navigate as part of our standard process.
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 in San Bernardino
San Bernardino’s building department typically issues ADU permits in 8-14 weeks for complete submittals, though geotechnical reviews in northern fault-proximity zones can add 3-6 weeks. We front-load the survey and engineering to prevent mid-process delays.
California law limits HOA prohibitions on ADUs, but HOAs may still enforce design guidelines, height limits, and setback rules; we review CC&Rs during preliminary design to flag conflicts before permit submittal.
San Bernardino County reassesses only the new ADU value, not the entire property, under California’s Prop 13 rules; the typical increase is modest relative to the rental income potential in this market.
Call (909) 359-6463 to schedule your free estimate. Every project receives a written price before work starts, per Haven Standard Clause 1, and our 365-Day Done Right Promise backs the finished work in writing.
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
"The rental income has covered the payment since the second month. They were realistic about the numbers rather than optimistic."
- Odette N."Every allowance was itemised at the start, so the finish selections did not turn into a surprise at the end."
- Benedict H."Garage conversion finished on the drawings and close to the schedule. They were honest that the sewer connection was the unknown, and it was."
- Arjun D.