San Bernardino ADU Cost & Permit Fee Calculator
A 600 sq ft ADU in San Bernardino runs about $247,000 all in, $8,228 of it city and school fees. Price your own build, fees and rental payback.
Updated · By Niraj Kumar · 11 sources
https://checkpre.com/construction/adu-cost-san-bernardino
1. The ADU
School fees start above 500 sq ft and impact fees at 750 sq ft.
Impact fees from 750 sq ft are scaled by the ADU's size against the house.
2. Site work
Distance from the house's sewer lateral to the ADU.
Architect, structural engineer, Title 24 and survey, as a share of the build. About 4% with a city pre-approved plan.
3. San Bernardino fees
San Bernardino estimate.
Waived: under 750 sq ft (state law).
Charged on new detached and attached units.
$5.38 a sq ft on the whole unit.
4. Rent and financing
HUD's FY 2026 fair market rent for the metro, a conservative figure. Enter a local listing to replace it.
Charged on the ADU's construction cost only; the house is not reassessed.
Net rent ÷ cap rate is how appraisers value income. 4-6% is typical for California rentals.
At 500 sq ft it would pay no school fees, saving $3,228.
- Construction
- $238,602
- build, site work, design and contingency
- City and school fees
- $8,228
- Monthly cash flow, year one
- $1,185
- on $1,700 rent
- Payback
- 14 years
- 5.8% cash-on-cash in year one
- Value added
- $284,468
- $37,638 more than it costs, at a 5% cap rate
- 1Construction$193,200
- 2Contingency$20,286
- 3Design and engineering$15,456
- 4Utility trenching$9,660
- 5School fees$3,228
- 6Permit and plan check$3,000
- 7Sewer and water capacity$2,000
Year-by-year rent and cash flowShowHide
| Year | Rent collected | Running costs | Loan | Cash flow | Cumulative |
|---|---|---|---|---|---|
| 1 | $19,380 | $5,157 | $0 | $14,223 | -$232,607 |
| 2 | $19,961 | $5,285 | $0 | $14,676 | -$217,930 |
| 3 | $20,560 | $5,417 | $0 | $15,143 | -$202,787 |
| 4 | $21,177 | $5,552 | $0 | $15,625 | -$187,162 |
| 5 | $21,812 | $5,691 | $0 | $16,122 | -$171,040 |
| 6 | $22,467 | $5,833 | $0 | $16,634 | -$154,407 |
| 7 | $23,141 | $5,979 | $0 | $17,162 | -$137,245 |
| 8 | $23,835 | $6,129 | $0 | $17,706 | -$119,539 |
| 9 | $24,550 | $6,283 | $0 | $18,267 | -$101,272 |
| 10 | $25,287 | $6,440 | $0 | $18,846 | -$82,425 |
| 11 | $26,045 | $6,602 | $0 | $19,443 | -$62,983 |
| 12 | $26,826 | $6,768 | $0 | $20,058 | -$42,924 |
| 13 | $27,631 | $6,939 | $0 | $20,693 | -$22,232 |
| 14 | $28,460 | $7,114 | $0 | $21,347 | -$885 |
| 15 | $29,314 | $7,293 | $0 | $22,021 | $21,136 |
| 16 | $30,193 | $7,477 | $0 | $22,716 | $43,852 |
| 17 | $31,099 | $7,666 | $0 | $23,433 | $67,285 |
| 18 | $32,032 | $7,860 | $0 | $24,172 | $91,457 |
| 19 | $32,993 | $8,059 | $0 | $24,934 | $116,391 |
| 20 | $33,983 | $8,263 | $0 | $25,719 | $142,111 |
How the San Bernardino ADU Cost & Permit Fee Calculator works
A new 600 sq ft detached ADU in San Bernardino costs about $247,000 to build in 2026, including $8,228 in permit, capacity and school fees. Impact fees do not apply under 750 sq ft. Rented at $1,700 a month, it pays back in about 14 years.
Cost = sq ft × rate₍type, finish₎ × city index + utility runs + panel + design + contingency + fees
fees = permit + impact × (ADU ÷ house, from 750 sq ft) + capacity (new builds) + school × sq ft (over 500)
Payback: Σ₍y₎ (rent × (1 − vacancy) − tax − insurance − upkeep − loan) ≥ cash investedThis page uses the same method as the California ADU Cost & ROI Calculator, which explains each term and assumption in full.
Worked example
A 600 sq ft detached one-bedroom ADU at standard finish behind a 1,600 sq ft house in San Bernardino, with utility lines run 50 ft from the house, paid in cash.
- 1Construction: 600 sq ft at about $322 a sq ft is $193,200; utility trenching adds $9,660, design $15,456 and a 10% contingency $20,286
- 2Fees: $3,000 in permit and plan check, no impact fees (under 750 sq ft), $2,000 in sewer and water capacity, and $3,228 in school fees
- 3Rent of $1,700 a month less 5% vacancy, property tax, insurance and upkeep leaves $14,223 a year
The ADU costs about $246,830 all in, $411 a sq ft, of which $8,228 is fees. The rent repays it in about 14.0 years, a 5.8% cash return in the first year.
Frequently asked questions
How much are ADU permit fees in San Bernardino?
For a new 600 sq ft detached ADU, city and school fees come to about $8,228: $3,000 in permit and plan check, $2,000 in sewer and water capacity charges and $3,228 in school fees. At 800 sq ft they rise to about $14,304, including $3,000 in impact fees. Going from 749 to 750 sq ft alone adds about $4,818. A garage conversion pays a smaller permit fee and no capacity charge.
How much does it cost to build an ADU in San Bernardino?
About $247,000 for a 600 sq ft detached ADU at standard finish, all in, or $411 a sq ft, and about $329,000 for 800 sq ft. Rented as a one-bedroom at $1,700 a month, the HUD fair market rent for the area, it would repay a cash build in about 14.0 years. A garage conversion typically costs 35-45% less.
What is unusual about ADU fees in San Bernardino?
No ADU-specific fee total is published; the figures are estimates in line with Riverside. San Bernardino City Unified collects its developer fee directly on ADUs over 500 sq ft.
Sources
- California Gov. Code §66324: impact fees and utility charges for ADUs · checked
- California Ed. Code §17620: school fees, with ADUs of 500 sq ft or less exempt · checked
- HCD, Accessory Dwelling Unit Handbook · checked
- State Allocation Board: Level 1 school fee raised to $5.38 per sq ft (28 January 2026) · checked
- HUD Fair Market Rents, FY 2026 · checked
- City of San José, Building Division fee schedule · checked
- City of Long Beach, Development Impact Fees · checked
- SFPUC, Capacity charges · checked
- City of Fresno, ADU Quick Start Guide · checked
- Los Angeles Department of City Planning, Parks Dedication Fee quick guide · checked
- SnapADU, City of San Diego ADU fees by size · checked
Related calculators
- California ADU Cost & ROI CalculatorWhat an ADU or garage conversion costs to build in 20 California cities, with each city's permit, impact and school fees and the state exemptions applied, and how long the rent takes to pay it back.
- Riverside ADU Cost & Permit Fee CalculatorA 600 sq ft ADU in Riverside runs about $255,000 all in, $8,228 of it city and school fees. Price your own build, fees and rental payback.
- Los Angeles ADU Cost & Permit Fee CalculatorA 600 sq ft ADU in Los Angeles runs about $315,000 all in, $16,728 of it city and school fees. Price your own build, fees and rental payback.
- Long Beach ADU Cost & Permit Fee CalculatorA 600 sq ft ADU in Long Beach runs about $294,000 all in, $8,872 of it city and school fees. Price your own build, fees and rental payback.