ADU in San Bernardino, CA
Junior ADU and interior conversion in San Bernardino typically runs $85,000-$165,000 all-in, drawings through final inspection, while site prep and utility upgrades add $15,000-$45,000 depending on whether your 1950s ranch needs a 200-amp panel and new water lateral. We’re Ellery ADU Studio, a design-build practice that handles the permit set, construction, and final inspection under one written contract - no designer-versus-builder blame gap. Call (951) 476-1467 for a free estimate with a written price before any work starts, per Haven Standard Clause 1.
Why San Bernardino Homes Are Different
San Bernardino’s flatland neighborhoods are dominated by 1950s-1970s concrete-slab ranch homes on 7,000-10,000+ sq ft lots - oversized by California standards, which puts most properties well within by-right lot-coverage limits. But those same mid-century homes almost universally have original 100-amp electrical panels and aging galvanized water supply lines that must be upgraded before the city will approve any new dwelling unit.
The valley floor regularly hits 108-115°F in summer and sits directly in the path of Cajon Pass Santa Ana wind events, so any ADU here needs robust HVAC and tight insulation to be rentable year-round. Foothill-adjacent parcels fall in Very High Fire Hazard Severity Zones, triggering ember-resistant venting and ignition-resistant cladding that coastal cities don’t require. Older flatland blocks around the Westside and near downtown often have rear-alley access and deep backyards suited for detached units, but the infrastructure upgrades are non-negotiable.
San Bernardino sits at the center of the Inland Empire’s warehouse and logistics corridor - BNSF intermodal, San Bernardino International Airport cargo ops, and the I-10/I-215 distribution belt - generating relentless demand from workers priced out of coastal rents. ADU rental yield here is unusually strong relative to still-low property values, making the math work faster than in Riverside or Redlands for many owners.
Our Main San Bernardino Services
San Bernardino homeowners most often call us about these three services, each with its own dedicated page and pricing.
ADU Design & Permitting in San Bernardino
We produce the full permit set - architectural drawings, structural calcs, Title 24 energy compliance, and San Bernardino building department submittal - as a standalone deliverable or bundled into construction. Most flatland ranches qualify for by-right approval under state law, but the city’s plan check still requires fire-department sign-off on water supply and access. ADU Design & Permitting in San Bernardino covers our full process and typical timeline.
Garage Conversion ADU in San Bernardino
The detached two-car garage is the most common conversion target in San Bernardino’s ranch neighborhoods. We assess slab thickness, roof structure, and whether the existing electrical feed can handle a second dwelling unit - usually it cannot, and the panel upgrade becomes part of the same contract. Garage Conversion ADU in San Bernardino details our assessment and pricing.
New Detached ADU in San Bernardino
Deep backyards on the Westside and downtown-adjacent blocks with rear-alley access are ideal for new detached units. We coordinate prefab systems from Abodu, Cover, or Dvele within the same single contract, handling foundation, utility trenching, and final tie-in. New Detached ADU in San Bernardino explains site requirements and brand options.
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.
Before
AfterJunior ADU & Interior Conversion in San Bernardino
Junior ADU and interior conversion in San Bernardino solves a specific problem: homeowners who want rental income or multigenerational housing without building new square footage. The city’s 1950s-1970s ranch stock offers generous interior footprints - 1,200-1,800 sq ft on a single level - with underutilized basements, attached garages, and spare rooms that convert efficiently. Santa Ana winds and 108°F summer highs make HVAC and insulation critical, not optional, for any interior unit to be legally rentable year-round. We handle Junior ADU & Interior Conversion as a single contract: permit set, construction, and final inspection at one written price.
Room-to-ADU Conversion
Signs you need it
You have a 200+ sq ft spare bedroom, den, or former formal living room you’re not using, and you want a separate entrance and kitchenette without adding to the building footprint.
What it costs in San Bernardino
Room-to-ADU conversions in San Bernardino typically run $85,000-$135,000 all-in, including the permit set, fire-rated separation from the main unit, kitchenette rough-in, and dedicated meter or submeter.
How we do it
We measure existing conditions, produce the permit set with fire-rated drywall assemblies and egress window specifications, then build to the drawings with a documented photo record on every visit.
Interior JADU
Signs you need it
You need a compact rental unit under 500 sq ft inside your existing home, with a separate entrance and efficiency kitchen, for a family member or single tenant.
What it costs in San Bernardino
Interior JADUs in San Bernardino typically run $75,000-$125,000 all-in, including permit set, fire separation, kitchenette, bathroom rough-in, and HVAC tied to the main system or mini-split.
How we do it
We identify the smallest viable footprint that meets JADU code, produce the permit set with owner-occupancy affidavit, and build with sound-rated assemblies between units.
What Junior ADU & Interior Conversion Costs in San Bernardino
| Item | Typical range in San Bernardino |
|---|---|
| Room-to-ADU conversion (all-in) | $85,000 - $135,000 |
| Interior JADU (all-in) | $75,000 - $125,000 |
| Above-garage ADU (all-in) | $110,000 - $175,000 |
Does a Junior ADU require a separate meter in San Bernardino?
No - California law allows JADUs to share electrical and water service with the primary residence, though many San Bernardino owners opt for submeters to simplify tenant billing. Call (951) 476-1467 for an exact quote on your setup - estimates are free.
Can I convert any room, or does it need to be on the ground floor?
Ground-floor rooms are simplest, but second-story conversions are allowed if they meet egress window requirements and the floor structure can support kitchen and bathroom loads - we assess this in our first site visit. Call (951) 476-1467 to schedule yours.
ADU Site Prep & Utilities in San Bernardino
ADU site prep and utilities in San Bernardino addresses the hidden infrastructure gap that stops most projects before they start: original 100-amp panels, galvanized water lines, and ungraded yards that don’t meet current code. The city’s 1950s-1970s ranch stock was built for single-family electrical loads, not second dwelling units, and San Bernardino’s building department enforces this strictly. Summer heat and Santa Ana wind exposure add further requirements - upsized HVAC electrical loads and, on foothill parcels, fire-resistant exterior assemblies. We bundle ADU Site Prep & Utilities into the main contract or price it separately for homeowners who need to phase their project.
Electrical Panel Upgrade
Signs you need it
Your main panel is 100 amps or has no open breaker spaces, which is standard on San Bernardino ranch homes built before 1980.
What it costs in San Bernardino
Electrical panel upgrades in San Bernardino typically run $4,500-$8,500 for 200-amp service, including permit, SCE coordination, and new grounding.
How we do it
We pull the permit, coordinate with Southern California Edison for service disconnect, install the new panel and load calculations for the ADU, then schedule city inspection.
Plumbing Lateral
Signs you need it
Your home has original galvanized or undersized copper supply lines, or the sewer lateral is clay or Orangeburg pipe common to the era.
What it costs in San Bernardino
Plumbing lateral replacement in San Bernardino typically runs $6,000-$14,000 depending on trench length, pavement restoration, and whether the connection point is in the alley or street.
How we do it
We locate the existing lateral with camera inspection, produce the trenching plan, replace with ABS or copper to code depth, and backfill with compaction testing.
What ADU Site Prep & Utilities Costs in San Bernardino
| Item | Typical range in San Bernardino |
|---|---|
| Electrical panel upgrade to 200A | $4,500 - $8,500 |
| Plumbing lateral replacement | $6,000 - $14,000 |
| Foundation and grading (new detached) | $12,000 - $28,000 |
Will San Bernardino let me start construction before utilities are upgraded?
No - the building department requires proof of adequate electrical, water, and sewer capacity before issuing the construction permit for the ADU itself. Call (951) 476-1467 and we’ll sequence the work so you’re not paying for idle time.
How long does the utility upgrade phase take?
Utility upgrades typically add 3-6 weeks before construction starts, mostly in SCE scheduling and city inspection availability; we coordinate this parallel to plan check to compress the overall timeline. Call (951) 476-1467 for a schedule on your property.
Brands We Service in San Bernardino
We specify and coordinate prefab and modular systems from Abodu, Cover, Dvele, and James Hardie within our single-contract model. Parts and warranty support are stocked through Inland Empire distributors, so replacement materials don’t wait on coastal shipping. Most brand-specific repairs or modifications schedule within 5-7 business days. See our brands for full compatibility details.
Pricing for ADU in San Bernardino, CA
| Service | Typical range in San Bernardino |
|---|---|
| Room-to-ADU conversion | $85,000 - $135,000 |
| Interior JADU | $75,000 - $125,000 |
| Above-garage ADU | $110,000 - $175,000 |
| Basement ADU | $95,000 - $155,000 |
| Attached addition ADU | $120,000 - $195,000 |
| Electrical panel upgrade (200A) | $4,500 - $8,500 |
| Plumbing lateral replacement | $6,000 - $14,000 |
| Foundation and grading (new detached) | $12,000 - $28,000 |
| Gas line extension | $3,500 - $7,500 |
| Landscaping and hardscape (post-build) | $8,000 - $22,000 |
Prices in San Bernardino push toward the high end when properties need combined electrical and plumbing upgrades, when foothill fire-zone requirements trigger ignition-resistant cladding, or when alley access is too narrow for standard equipment and hand-work is required. Every project is quoted with a written price before any work begins, per Haven Standard Clause 1 - no change orders, no door-side upsells.
Neighborhoods We Serve in San Bernardino
We work across San Bernardino’s flatland and foothill neighborhoods, from the ranch-stock blocks near downtown to the larger parcels edging the National Forest. Crews dispatch from our Inland Empire office; most San Bernardino properties are within 20 minutes of scheduled arrival.
- Westside
- Del Rosa
- Arrowhead
- University District
- Mount Vernon
Service Area - Cities Near San Bernardino
Our crews serve the full Inland Empire corridor. We regularly schedule projects in Rialto, CA, Redlands, CA, Riverside, CA, and Fontana, CA, with the same written-price guarantee and documented photo record on every visit.
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
By-right ADU applications typically clear plan check in 60-90 days if the submittal is complete; incomplete permit sets or properties needing zoning verification take longer. We produce the full set to avoid this delay.
Foothill-adjacent parcels in Very High Fire Hazard Severity Zones require ember-resistant venting, ignition-resistant exterior cladding, and fire-rated assemblies between units; flatland properties follow standard California Building Code with standard smoke and CO detection.
California law prohibits HOAs from outright banning ADUs, but some San Bernardino-area associations impose design guidelines or parking requirements that affect placement; we review CC&Rs during our first site visit and address conflicts in the permit set.
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."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."Every allowance was itemised at the start, so the finish selections did not turn into a surprise at the end."
- Benedict H.