Prefab ADUs in Fontana
Fontana permits more ADUs every year — 240 in 2025 — and a detached ADU up to 800 sq ft needs no parking and no design review. We deliver an all-in prefab ADU from our factory in Lathrop — permits, foundation, delivery and installation included — at one fixed price.
Free lot check · zoning, setbacks, utilities · reply with a fixed price
Licensed builder · Our own factory in Lathrop, CA
Real homes we build, start to finish
Quick answer
ADUs in Fontana — key facts for 2026
Most Fontana homeowners can add a detached ADU of up to 800 sq ft with no parking, no design review and no impact fees under 750 sq ft. Bay Modular delivers a factory-built ADU all-in for $124,900–$271,900 — the same price anywhere in California.
- Can I build an ADU in Fontana?
- Yes, on most single-family lots. Fontana allows a detached ADU up to 800 sq ft and 16 ft tall with 4-ft side and rear setbacks, no parking and no design requirements; larger ADUs up to 1,200 sq ft add local rules.
- How long does a Fontana ADU permit take?
- ADUs that meet the state standards are approved ministerially; state law requires a decision within 60 days of a complete application.
- What fees does Fontana charge?
- No impact fees under 750 sq ft (state law). Fontana Unified's school fee applies only to ADUs over 500 sq ft.
- How much does a prefab ADU cost in Fontana?
- Bay Modular: $124,900–$271,900 all-in, the same price as anywhere in California, permits and installation included.
- How many ADUs does Fontana build?
- 240 ADU permits in 2025 — 27% of all new homes permitted in the city, up from 86 in 2021.
- What does an ADU rent for in Fontana?
- Average asking rent in Fontana was $3,190 a month in August 2026 (Zillow), up 3.7% in a year.
Sources: HCD APR 2025, Fontana Municipal Code Sec. 30-467 and the City’s ADU Information Sheet (March 2026), Zillow ZORI Aug 2026. Last reviewed October 2026.
Fontana in numbers
Fontana builds more ADUs every year
ADU permits grew every year from 86 in 2021 to 240 in 2025 — 27% of all new homes permitted in Fontana last year were ADUs.
ADU permits issued in the City of Fontana
Source: California HCD Annual Progress Report data (Table A2), City of Fontana, permits issued per year. Percent = ADUs among all housing units permitted in the city that year.
average Fontana asking rent in one year ($3,076 → $3,190)
Zillow Observed Rent Index, City of Fontana, Aug 2026more ADU permits in 2025 than in 2021 (86 → 240)
HCD APR data, 2021–2025Can I build in Fontana?
Most Fontana lots with a house can add an ADU
Fontana’s ADU rules (Municipal Code Sec. 30-467) split detached ADUs into two classes. Here is what matters for most homeowners:
A Class 1 detached ADU can be up to 800 sq ft — all our models fit. Class 2 allows up to 1,200 sq ft with extra local rules.
4 ft from side and rear lot lines; 16 ft tall for a Class 1 ADU (16–18 ft for Class 2, with an 18-ft front setback).
A Class 1 ADU has no architecture or design requirements — approved ministerially under state standards.
No parking for a Class 1 detached ADU. Class 2 and new attached ADUs need one space unless an exemption applies.
One JADU, one Class 1 ADU and one conversion ADU on a single-family lot.
Fontana publishes pre-approved ADU plans under AB 1332 — we use our own HCD-approved designs.
Based on Fontana Municipal Code Sec. 30-467 and the Planning Department’s ADU Information Sheet (updated March 2026). Not legal advice — rules depend on your exact lot. More in our ADU guides.
New in 2027: under AB 956 (Chapter 791, Statutes of 2026), from January 1, 2027 state law lets you build two detached ADUs on a lot with a single-family home, and HOA rules can’t block an ADU on a lot zoned to allow one.
Costs & fees in Fontana
What an ADU costs in Fontana
Same all-in price as anywhere in California. Our models are all under 750 sq ft, so none pays impact fees — and four of five pay no school fees.
| Model | All-in price | School fees | City impact fees |
|---|---|---|---|
| Backyard Studio120 sq ft · home office or guest studio, not a rentable ADU | $75,900 | $0 | $0 |
| Small Studio256 sq ft | $124,900 | $0 | $0 |
| Large Studio ADU320 sq ft | $154,900 | $0 | $0 |
| 1 Bedroom ADU480 sq ft | $214,900 | $0 | $0 |
| 2 Bedroom ADU640 sq ft | $271,900 | $3,443 | $0 |
Sources: Gov. Code §66311.5; Ed. Code §17620 and State Allocation Board 2026 school fee maximum; Fontana Unified School District developer fees. Launch pricing runs through December 31, 2026. Comparison is general — every project differs.
Renting in Fontana
Renting out an ADU in Fontana
average asking rent for all homes in Fontana — up 3.7% in a year. HUD's 2027 fair rent for a 1-bedroom in the area is $1,705.
Zillow Observed Rent Index, City of Fontana, Aug 2026 · HUD FY2027 FMR ADU for rental incomeA JADU can't be rented for less than 30 days; long-term tenants are the safe plan for any ADU.
Owner occupancy applies only to a JADU that shares a bathroom with the main house.
A new ADU is exempt from California's statewide rent cap (AB 1482) for 15 years after its certificate of occupancy.
Same money, other options
Yearly income per dollar, before taxes and costs. An ADU wins because you already own the land. Full comparison →
Sources: Fontana ADU Information Sheet (March 2026); Gov. Code §66333; Civil Code §1947.12. Comparison: HUD FY2027 2-bedroom Fair Market Rent, Riverside-San Bernardino-Ontario ($2,103) × 12 ÷ $271,900; U.S. Treasury (Oct 6, 2026); FTSE Nareit (Sep 2026); Zillow ZORI ÷ ZHVI, Riverside metro (Aug 2026); FDIC (Sep 2026). Not legal or investment advice.
Permits in Fontana
How your Fontana permit works — we handle it
Free lot check
Zoning, setbacks, ADU class, sewer, water and power for your Fontana address.
Plans & submittal
Our HCD-approved plans plus your site plan. A Class 1 ADU is reviewed under state standards — no design review.
City review
Planning and Building & Safety plan check; we answer comments and arrange the ADU address.
Decision in 60 days
State law requires a decision on a complete ADU application within 60 days. Your ADU is built in our factory meanwhile.
Install & move in
Delivered from our Lathrop factory, installed in about a week, inspected, then your Certificate of Occupancy.
Based on the City’s ADU Information Sheet (March 2026) and Gov. Code §66317. Fontana also publishes AB 1332 pre-approved ADU plans.
Why now
Start your Fontana ADU with zero risk
Lock in launch pricing, see exactly what you get, and only decide once you have a fixed price for your lot.
All-in from $75,900 — everything included
- Backyard Studio (home office)$75,900All-in · fixed in writing
- Small Studio$124,900All-in · fixed in writing
- Large Studio ADU$154,900All-in · fixed in writing
- 1 Bedroom ADU$214,900All-in · fixed in writing
- 2 Bedroom ADU$271,900All-in · fixed in writing
Zero-risk start
- Free lot check & quoteNo obligation, no credit card.
- One fixed all-in priceDesign, permits, delivery and install — one number.
- HCD-approved plansState approval #1585366, financed and appraised like a home.
- 2-year warrantyOn materials and workmanship.
Visit our factory in Lathrop, CA and walk through a finished ADU.
Fontana ADU questions
Read our ADU guides, see all of California, or call (209) 214-6845.
Can I build an ADU on my lot in Fontana?
Most Fontana single-family lots can add a Class 1 detached ADU up to 800 sq ft and 16 ft tall, with 4-foot side and rear setbacks and no parking, plus a JADU and a conversion ADU. We check your address for free.
How much does an ADU cost in Fontana?
Our all-in prices are the same as anywhere in California: from $124,900 for a Small Studio to $271,900 for a 2 Bedroom ADU, with launch pricing through December 31, 2026. No impact fees under 750 sq ft, and school fees only above 500 sq ft.
How long does an ADU permit take in Fontana?
A Class 1 ADU is approved ministerially under state standards, and state law requires a decision within 60 days of a complete application. Your ADU is built in our factory at the same time, so most projects take 4–6 months from signing to keys.
Do I need parking for an ADU in Fontana?
Not for a Class 1 detached ADU up to 800 sq ft. Larger Class 2 and new attached ADUs need one space unless an exemption in FMC Sec. 30-467 applies.
What is the difference between Class 1 and Class 2 ADUs?
Class 1 follows state rules: up to 800 sq ft, 16 ft, no parking, no design requirements. Class 2 allows up to 1,200 sq ft but needs parking, an 18-ft front setback and a compatible design.
Do I have to live on the property?
No. Owner occupancy applies only to a JADU that shares a bathroom with the main house.
Can Bay Modular deliver to Fontana?
Yes. We build in our Lathrop factory and deliver statewide at the same all-in price, including Southern California.
Is an ADU a better investment than a rental property in Fontana?
For most homeowners with room on their lot, yes: you don't buy land. A 2 Bedroom ADU at HUD's 2027 fair rent for a 2-bedroom in the Riverside-San Bernardino area ($2,103) earns about 9.3% a year on its price before costs, vs. about 5.2% for a typical Inland Empire rental home (Zillow, Aug 2026). Not investment advice.
Free · no obligation
Can you build an ADU on your Fontana lot?
Send your Fontana address. We'll check zoning, setbacks, ADU class and utilities, and send a fixed all-in price — permits included.
HCD-approved plans (#1585366) · 2-year warranty · factory in Lathrop, CA
Sources: California HCD Annual Progress Report data, Table A2 (City of Fontana, 2021–2025, updated Oct 2026); Zillow Observed Rent Index, City of Fontana (Aug 2026); HUD FY2027 Fair Market Rents (Riverside-San Bernardino-Ontario); Fontana Municipal Code Sec. 30-467; City of Fontana ADU Information Sheet (March 2026) and Standard ADU Plans page. Prices: Bay Modular, October 2026. Not legal advice.