ADU in San Bernardino, CA
A Junior ADU & Interior Conversion in San Bernardino typically runs $85,000-$165,000 all-in, drawings through final inspection, while full site prep and utility work adds $25,000-$75,000 depending on seismic grading and electrical service. We’re Ellery ADU Studio, a design-build practice with our Inland Empire office coordinating crews across San Bernardino, and we handle the permit set, construction, and utility tie-ins under one written contract at one written price. Call (760) 493-7752 to schedule your free estimate.
Why San Bernardino Homes Are Different
San Bernardino’s housing stock is dominated by 1950s-1970s wood-frame stucco tract homes on lots of 7,500-12,000 square feet, far roomier than coastal LA parcels but frequently carrying 60- or 100-amp main panels and detached single-car garages never meaningfully updated. The valley basin traps summer heat exceeding 108°F, demanding Title 24 insulation packages and properly sized mini-splits that contractors in milder cities sometimes underspec. Winter nights dip below freezing, so exposed supply lines in uninsulated garage slabs freeze and burst without proper rough-in protection.
Every ADU foundation here must clear seismic engineering review because San Bernardino sits directly above active fault strands tied to the San Andreas system, adding design cost and timeline that contractors in Fontana or Rialto rarely encounter. The building department, still rebuilding staffing capacity post-bankruptcy, runs slower inspection queues than neighboring cities, so experienced local contractors schedule the next inspection the moment a stage is roughed in, not after completion.
Our Main San Bernardino Services
San Bernardino homeowners most often call us about two services, with three additional project types we also build across the city:
ADU Design & Permitting in San Bernardino
We produce the full permit set, structural calculations, and Title 24 energy compliance as the core product, not an afterthought. In San Bernardino, that means seismic engineering review for every foundation and proactive scheduling around the building department’s inspection queues. ADU Design & Permitting in San Bernardino covers drawings through issued permit.
Garage Conversion ADU in San Bernardino
Single-car detached garages are everywhere in San Bernardino’s postwar tracts, and most need panel upgrades, slab moisture barriers, and freeze-protected plumbing before they’re habitable. We assess the existing slab thickness and electrical service in the first site visit. Garage Conversion ADU in San Bernardino handles the full conversion.
New Detached ADU in San Bernardino
Those 7,500-12,000 square foot lots give genuine room for freestanding backyard cottages, but seismic engineering and summer heat-gain sizing make San Bernardino new construction different from standard Inland Empire practice. We coordinate prefab systems from Plant Prefab and Tuff Shed within our single contract. New Detached ADU in San Bernardino covers ground-up builds.
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
San Bernardino’s vintage tract homes with their generous square footage and underutilized interior spaces are ideal candidates for Junior ADU & Interior Conversion, though the same 60-amp panels and uninsulated perimeter walls that make these homes affordable also create hidden electrical and thermal challenges. A Junior ADU here converts existing conditioned space within the primary residence, avoiding new foundation work but demanding careful fire-separation detailing and independent utility metering that the original builders never anticipated.
Room-to-ADU Conversion
Signs you need it
You have a 250-plus square foot den, formal living room, or ground-floor bedroom that sits unused while housing costs climb.
What it costs in San Bernardino
Room-to-ADU conversions in San Bernardino typically run $85,000-$140,000 all-in, including fire-rated separation, independent egress, and electrical subpanel work.
How we do it
We measure existing conditions, produce the permit set with fire-separation details, upgrade electrical service as needed, and build to the drawings through final inspection with a documented photo record at every visit.
Interior JADU
Signs you need it
Your home has a separate entrance to an existing bedroom suite or attached in-law area with its own bathroom rough-in.
What it costs in San Bernardino
Interior JADUs in San Bernardino typically run $75,000-$125,000, including kitchenette, mini-split, and owner-occupancy covenant filing.
How we do it
We verify the separate entrance meets code, design the kitchenette and bath layout for the permit set, install efficient heating and cooling sized for the space, and file the JADU covenant before final.
What Junior ADU & Interior Conversion Costs in San Bernardino
| Item | Typical range in San Bernardino |
|---|---|
| Room-to-ADU conversion (all-in) | $85,000-$140,000 |
| Interior JADU (all-in) | $75,000-$125,000 |
| Electrical panel upgrade (if needed) | $4,500-$9,000 |
Does a Junior ADU need its own electric meter in San Bernardino?
No, a Junior ADU can share the primary residence meter, though we often recommend a subpanel to prevent overload on 60-amp legacy service common in San Bernardino’s postwar tracts. Call (760) 493-7752 for an exact quote, estimates are free.
Can I convert any room, or does it need a separate entrance?
Interior JADUs require a separate exterior entrance per state code; Room-to-ADU conversions need independent egress but not necessarily a full separate door if other exits meet code. Call (760) 493-7752 for an exact quote, estimates are free.
ADU Site Prep & Utilities in San Bernardino
San Bernardino’s postwar tract homes were built with minimal infrastructure for second units, so nearly every ADU project here demands electrical panel upgrades, new plumbing laterals, and seismic grading that contractors in newer cities skip. ADU Site Prep & Utilities handles these prerequisites as a scoped line item within our single contract, not as open-ended extras, because Haven Standard Clause 1 locks the written price before work starts.
Electrical Panel Upgrade
Signs you need it
Your main panel is rated 60 or 100 amps, has no open breaker slots, or shows corrosion from decades of valley heat cycling.
What it costs in San Bernardino
Electrical panel upgrades in San Bernardino typically run $4,500-$9,000 including permit, SCE coordination, and new grounding.
How we do it
We verify load calculations for the ADU, specify the new panel and service conduit, pull the permit, coordinate with Southern California Edison, and pass inspection before rough-in.
Plumbing Lateral
Signs you need it
Your existing sewer line is cast iron with bellied sections, or the water main is galvanized steel with pressure below 40 PSI at the rear of the property.
What it costs in San Bernardino
Plumbing lateral replacement or extension in San Bernardino typically runs $8,000-$18,000 depending on trench length and street-to-house distance.
How we do it
We camera the existing line, produce the permit set with trench details and backflow prevention, excavate with proper shoring, install ABS or copper as specified, and pressure-test before cover.
What ADU Site Prep & Utilities Costs in San Bernardino
| Item | Typical range in San Bernardino |
|---|---|
| Electrical panel upgrade | $4,500-$9,000 |
| Plumbing lateral (replace/extend) | $8,000-$18,000 |
| Foundation & seismic grading | $12,000-$28,000 |
Is the electrical upgrade included in the ADU price or separate?
We line-item it separately in your written quote so you see exactly what the existing home needs versus what the new unit needs, per Haven Standard Clause 5. Call (760) 493-7752 for an exact quote, estimates are free.
How long does utility coordination take with SCE?
Southern California Edison typically schedules service upgrades within 4-6 weeks in San Bernardino, so we submit immediately after permit issuance, not after rough-in. Call (760) 493-7752 for an exact quote, estimates are free.
Brands We Service in San Bernardino
We specify and coordinate prefab and modular systems from Plant Prefab, Tuff Shed, and James Hardie within our single contract, with parts and assembly sequences documented in the permit set before construction starts. Our brands page lists full specifications and typical San Bernardino turnaround timelines.
Pricing for ADU in San Bernardino, CA
| Service | Typical range in San Bernardino |
|---|---|
| Room-to-ADU conversion | $85,000-$140,000 |
| Interior JADU | $75,000-$125,000 |
| Electrical panel upgrade | $4,500-$9,000 |
| Plumbing lateral | $8,000-$18,000 |
| Foundation & seismic grading | $12,000-$28,000 |
| Gas line extension | $3,500-$8,500 |
| Landscaping & hardscape (post-build) | $5,000-$15,000 |
| Full site prep & utilities package | $25,000-$75,000 |
Seismic engineering review and Title 24 heat-gain compliance push San Bernardino prices above standard Inland Empire ranges. Every project is quoted with a written price before any work begins, per Haven Standard Clause 1, with scope locked at signing per Clause 5.
Neighborhoods We Serve in San Bernardino
Our crews work across San Bernardino’s established neighborhoods, from the historic downtown-adjacent districts to the postwar tracts north and south of the 210. Scheduling and dispatch are coordinated from our Inland Empire office with response typically next business day for site visits.
- Arrowhead
- Del Rosa
- Mount Vernon
- Valley View
- Westside
Service Area - Cities Near San Bernardino
We serve homeowners throughout the San Bernardino Valley and surrounding mountain communities. Recent projects have taken us to Highland, CA for hillside grading work, Rialto, CA for garage conversions on similar postwar stock, Crestline, CA for snow-load foundation design, and Fontana, CA where seismic requirements differ meaningfully from San Bernardino’s fault-strand conditions.
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 runs 8-14 weeks for ADU plan check, longer than Redlands or Riverside due to staffing capacity still rebuilding after the bankruptcy years. We submit complete permit sets with pre-checked Title 24 and seismic calcs to avoid the revision cycles that add months.
California law prohibits HOAs from outright banning ADUs, but some San Bernardino neighborhood associations impose design guidelines on exterior materials or setback landscaping that affect your project’s look and cost. We review CC&Rs during our first site visit and note any compliance requirements in your written scope.
San Bernardino County reassesses only the new ADU value, not the entire property, under California’s Prop 13 rules. The city has actively streamlined ADU permitting partly to expand its property-tax base, so the incremental increase is typically predictable and modest relative to rental income potential.
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
"They walked us through setbacks and utility capacity before we paid anything, and told us one of our two options was not going to get approved."
- Mireille T."The rental income has covered the payment since the second month. They were realistic about the numbers rather than optimistic."
- Odette N."The permit set and the build were one contract with one number. Our neighbours used two firms and spent a year watching them blame each other."
- Helena V.