ADU Builders in San Bernardino, CA (2026)

ADU builders in San Bernardino typically quote $150,000-$300,000 for a new detached unit, or about $180-$280 per square foot, including design, permitting, and construction. A garage conversion runs $75,000-$150,000 and a prefab/modular ADU averages $180,000-$320,000. Add city permit and plan-review fees (The posted Building & Safety fee schedule (07/2020) has no ADU line, so a new detached unit is priced like a new in-fill dwelling: plan review at the hourly rate of $122.37 (5 hours, about $612, for a new dwelling; 3 hours, about $367, for an addition), a building permit of $1,461 for a unit up to 1,200 sq ft (Table 1B, including electrical, plumbing and mechanical inspections) or $1.92 per sq ft for an attached unit with a bath or kitchen ($375 minimum, $1,459 maximum up to 1,200 sq ft), plus a 2% technology fee and 2% General Plan maintenance fee, a $55 zoning consistency review, $167.40 for the certificate of occupancy when it is on the building permit, state SMIP at 0.0001 x valuation and archive fees of $3.15 per plan sheet; expect roughly $2,300-$2,800 in city plan-check and permit fees for a detached ADU before school, sewer and impact fees. The Planning Division's February 2024 schedule lists no ADU review fee; MC-1659 lets the city set an ADU-permit processing fee by council resolution (4.b), so confirm with Planning. Pre-approved plans are bought from their designer at the designer's price) plus impact fees of None for a JADU or for an ADU of 750 sq ft or less of interior livable space (Gov. Code 66311.5(c)(1) as amended by SB 543; MC-1659 8.a words the city's version as 'less than 750 sq ft', and the state boundary controls). Above 750 sq ft the fee is prorated: ADU floor area divided by the main house's floor area, times the full single-family fee (8.a.iii). The city's posted Land Development impact-fee schedule (effective February 15, 2022, indexed to the ENR index every July 15, so ask for current figures) totals about $17,300 per detached dwelling: local circulation $232.94, regional circulation $2,435, storm drain $3,925.91, law enforcement $639.07, library $637.89, aquatic $326.11, public meeting facilities $1,089.54 and parkland $8,044.32, so an 800 sq ft ADU behind a 1,600 sq ft house would owe about half of that. School fees are separate: San Bernardino City USD charges $5.38 per sq ft (effective August 3, 2026) on an ADU over 500 sq ft and nothing at 500 sq ft or less (66311.5(c)(3)); Rialto and Redlands USD set their own rates and the city asks for a school-fee letter at 501 sq ft and up. Sewer: SBMWD Rule 25 lists a $180 application fee, a $3,500 residential treatment capacity charge per dwelling unit and $420 per bedroom for collection capacity; a conversion ADU or JADU inside existing space owes no new connection or capacity charge (8.b.ii, 66311.5(d)), and a new detached unit may be charged only in proportion to its burden by floor area or fixture units (8.b.iii, 66311.5(e)). Addresses in the East Valley Water District pay that district instead. Quotes for the same scope commonly vary 20-40% between builders, so collect at least three bids.

Look for a licensed contractor with completed ADU projects in San Bernardino specifically — ADUs involve local zoning, setback rules, and utility connections that general remodelers may not have handled. Verify the license, ask for an ADU-specific portfolio and references, confirm they carry liability and workers' comp insurance, and get a written fixed-price or detailed bid. Submit a request below and we'll forward it to local ADU builders serving San Bernardino for free quotes.

Most full-service ADU builders manage the permit process for you. In San Bernardino the approval process is "Ministerial: every ADU and JADU needs an ADU permit and a building permit, approved without a hearing when the plans meet 19.04.030(2)(P) (subsection 4). The city's ADU page lays out the steps: 1) check zoning on the city GIS map and whether the lot is in a high-wind, high-seismic or fire-severity area; 2) submit plans to the Planning Division (909-998-2300, cityofsbplanning@sbcity.org) for planning pre-approval; 3) file at the Building & Safety counter, 201 N. E Street, 3rd floor: three sets of 24 x 36 in. plans with photovoltaic shown (it cannot be deferred), two sets of structural and energy calculations and spec sheets, the building permit application, and the hold-harmless form if you use a pre-approved plan; plan-review fees are paid at submittal and permit fees before issuance; 4) obtain clearances from San Bernardino County Fire (online only), the Water Department for a sewer capacity/will-serve letter (1350 S. E Street, 909-384-5095), the NPDES and Land Development sections of Public Works, and Real Property for the new address, then send them to Community Development or drop them at the counter; 5) plan review, then permit issuance once fees and any school-fee letter are in hand; 6) inspections by phone at 909-998-2000. A denial must list every deficiency and how to fix it, and can be appealed in writing to the Planning Commission, which rules within 60 business days (4.c.iv-v). Owner-builders may pull their own permit with the Owner-Builder Acknowledgment form" with a typical review timeline of 15 business days for the city to tell you in writing whether the application is complete (and what is missing), the same 15 business days for each resubmittal, then 60 days from a complete application to approve or deny or the ADU is deemed approved; the clock pauses only if you ask for a delay or the ADU is filed with a new house (19.04.030(2)(P)(4)(c), SB 543). Building & Safety says a first plan-check round takes 15-20 business days and each later round 10-15 business days, with status on the online permit portal. Confirm in writing whether permit fees, plan check (Plan review is paid at submittal at $122.37 per hour (5 hours for a new dwelling, 3 for an addition) and is done in-house; expedited review goes to an outside vendor at the vendor's rate. The city quotes 15-20 business days for the first round and 10-15 for each later round, inside the 60-day statutory decision window. Plans must follow the 2025 California building codes in force since January 1, 2026, and fire sprinklers are required only if the main house has them (19.04.030(2)(P)(6)(c))), and impact fees are included in the bid or billed separately.

Plan for the permit review (15 business days for the city to tell you in writing whether the application is complete (and what is missing), the same 15 business days for each resubmittal, then 60 days from a complete application to approve or deny or the ADU is deemed approved; the clock pauses only if you ask for a delay or the ADU is filed with a new house (19.04.030(2)(P)(4)(c), SB 543). Building & Safety says a first plan-check round takes 15-20 business days and each later round 10-15 business days, with status on the online permit portal in San Bernardino) plus construction. Most detached ADUs take 4-8 months of construction after permits are issued; garage conversions and prefab units are often faster. Ask each builder for a realistic schedule and what could delay it.