Everything homeowners need to know about building an accessory dwelling unit in Fremont - size limits, setbacks, permits, and how California's statewide ADU law shapes what you can build here.
Last verified: August 2026
9/10 · Very ADU-friendly
1,200 sq ft
Max ADU size
16 ft*
Max height
Not required
Owner-occupancy
By-right
Permit type
This page summarizes Fremont Municipal Code Chapter 18.190 (Accessory Dwelling Units), layered on top of California's statewide ADU law (Government Code Section 65852.2), for general reference - it is not legal advice. Regulations change; always confirm current requirements with Fremont Planning, Building & Permit Services before designing or applying for permits. See sources below.
Zoning & size requirements
What you're allowed to build
ADU type
Max size
Max height
Notes
Detached (new construction)
1,200 sq ft
16 ft (18 ft within a half mile of major transit; +2 ft allowed to match the primary roof pitch)
4 ft side/rear setback; no setback for conversions of existing structures
Attached (new addition)
1,000 sq ft, and no more than 50% of the primary dwelling's floor area
Underlying zone limit, capped at 30 ft
Front setback matches the primary dwelling, waived if it would block a state-protected ADU
Junior ADU (JADU)
500 sq ft
Within existing primary structure
Owner-occupancy only required if the JADU shares sanitation facilities with the house
Allowed zoning districts
Single-family and multifamily residential zoning districts citywide, per state law and FMC Chapter 18.190. Multifamily properties can add up to 8 detached ADUs on an existing lot, plus interior conversions of up to 25% of existing units. Confirm your parcel's zoning district with Fremont Planning.
Additional standards
Setbacks, parking & other rules
Setbacks
4 ft from side and rear property lines for new construction; conversions of existing garages or other structures are exempt from setback requirements
Parking
No off-street parking required for any ADU, and no replacement parking required when a garage or driveway space is converted or demolished to build one
Units per lot
A single-family lot can generally add one detached new-construction ADU plus one conversion ADU or JADU within existing space; multifamily lots allow more. Exact stacking depends on your lot - confirm with Fremont Planning.
Owner-occupancy
Not required for a standard ADU, under both FMC 18.190.005 and statewide law (AB 976, effective January 1, 2024). JADUs require it only when sanitation facilities are shared with the primary home.
Building code
Must meet the California Residential Code as locally adopted by Fremont (2025 California Building Standards Code, effective January 1, 2026)
Rental rules
No separate ADU-specific rental license is required by the city; standard California landlord-tenant law applies. Confirm any short-term rental rules separately if that's the plan.
Ordinance history
How Fremont's ADU rules got here
2017Statewide by-right ADU law takes effect. California Government Code Section 65852.2 requires cities, including Fremont, to approve most ADUs ministerially - without a public hearing or discretionary review.
2020Ordinance updated for the 2020 state overhaul. Fremont amended its ADU regulations to conform with AB 68, AB 881, AB 587, AB 671, and related 2019-2020 state legislation that expanded where and how large ADUs could be built.
2023Ordinance 06-2023 adopted. Adopted by the City Council on July 11, 2023 and effective August 11, 2023, further amending Fremont's ADU standards.
2024Owner-occupancy ban and multifamily expansion. Statewide AB 976 permanently eliminated owner-occupancy requirements for standard ADUs, and SB 1211 let multifamily properties add up to 8 detached ADUs on one lot.
2026Ordinance 02-2026 adopted. Adopted May 5, 2026, aligning Fremont's local code with the latest statewide ADU package, including the stronger deemed-approved remedy for missed review deadlines under SB 543.
Worth knowing: Fremont also runs a Preapproved ADU Plans program, letting homeowners build from a designer-submitted plan set the city has already reviewed, which can shorten plan review meaningfully compared with a fully custom design. Even so, Bay Area land and construction costs remain the bigger practical barrier for many homeowners now that the zoning itself is this permissive.
Permit process
How Fremont ADU permitting works
1
Pre-application check
Confirm your lot's zoning district and any site constraints with Fremont Planning, Building & Permit Services before you design.
2
Choose standard or preapproved plans
Using one of the city's Preapproved ADU Plans can shorten plan review meaningfully compared with a fully custom design; either path is ministerial.
3
Prepare your plan set
You'll need a site plan, floor plans and elevations for the ADU, and existing floor plans of the primary home to verify size limits.
4
Submit your application
File through Fremont's permitting system for ministerial review - no public hearing or discretionary approval is required for a qualifying ADU.
5
Plan review & permit issuance
The city must decide within the state-mandated 60-day window; if it misses the deadline, the application is deemed approved under SB 543.
6
Construction & inspections
Once your building permit is issued, schedule the standard framing, plumbing, electrical, and final inspections as construction proceeds.
Fees and timelines are approximate and can vary by project type - confirm current figures with Fremont Planning, Building & Permit Services.
Budgeting
What it costs to build an ADU in Fremont
Garage conversion
Roughly $70,000-$180,000, the least expensive path since the shell already exists
Basement conversion
Basements are uncommon in California construction generally, so this is a smaller category locally; where they exist, conversions run roughly $100,000-$220,000 based on regional contractor estimates
New detached ADU
Roughly $150,000-$350,000+ for a code-compliant, freestanding unit, with Bay Area land and labor costs pushing many projects toward the upper end
Impact fees
ADUs of 750 sq ft or less are exempt from most local impact fees under state law (Government Code Section 66311.5); larger ADUs may owe proportional fees, and school fees can apply above 500 sq ft of livable area
Permit & plan-check fees
Design review, building permit, and plan-check fees apply and vary by project scope - confirm the current fee schedule with Fremont Planning, Building & Permit Services
These are general ranges from local contractor estimates and regional reporting, not quotes - actual cost depends heavily on lot conditions, finishes, and utility access. Fremont's Preapproved ADU Plans program can reduce design costs and review time for homeowners who don't need a fully custom layout.
Before you apply
Tips for a smooth approval
Look at the Preapproved ADU Plans list first. If one fits your lot, you can skip much of the custom design process and move to permitting faster.
Confirm your zoning district and lot constraints early. A pre-application check with Fremont Planning avoids redesigning a project that doesn't fit your parcel.
Keep new construction at or under 750 sq ft if avoiding impact fees matters to you. Crossing that threshold can trigger proportional local impact fees and, above 500 sq ft, school fees.
Budget for Bay Area construction costs, not national averages. Local labor and materials pricing tends to run well above the low end of typical ranges.
Get a complete application in the first time. The city's ministerial review clock runs from a deemed-complete application, so missing documents can add real delay even with the deemed-approved backstop.
FAQ
Common questions
Do I need to live on the property to build an ADU in Fremont?
No. California law (AB 976, effective January 1, 2024) permanently bars cities from requiring owner-occupancy for standard ADUs, and Fremont's own code reflects that. A Junior ADU only requires owner-occupancy if it shares sanitation facilities with the primary home.
How many ADUs can I build on one lot in Fremont?
A typical single-family lot can add a detached new-construction ADU plus a conversion ADU or JADU within existing space. Multifamily properties can add up to 8 detached ADUs plus interior conversions of up to 25% of existing units. Exact stacking depends on your lot - confirm with Fremont Planning.
Do I need extra parking for an ADU?
No. Fremont doesn't require off-street parking for any ADU, and you don't have to replace a garage or driveway space that's converted or demolished to build one.
How long does the permit process take?
Applications are reviewed ministerially within the state-mandated 60-day window. If the city misses that deadline, the application is deemed approved under SB 543. Using a Preapproved ADU Plan can speed up the design and review portion of the timeline.
What's the maximum size for a detached ADU in Fremont?
Up to 1,200 sq ft, with a 16 ft height limit (18 ft within a half mile of major transit, plus 2 ft to match the primary dwelling's roof pitch).
How much does an ADU cost to build in Fremont?
Garage conversions tend to run roughly $70,000-$180,000, basement conversions (less common in California) roughly $100,000-$220,000, and new detached units $150,000-$350,000 or more, based on local contractor estimates and regional reporting. Bay Area labor and land costs push many projects toward the higher end.
Are there fees specifically for ADUs in Fremont?
ADUs of 750 sq ft or less are exempt from most local impact fees under state law. Larger ADUs may owe proportional impact fees, and school fees can apply above 500 sq ft of livable area. Design review, building permit, and plan-check fees also apply - confirm current amounts with the city.
Can I add multiple ADUs if I own a multifamily property in Fremont?
Yes. Under statewide SB 1211 (2024), owners of existing multifamily properties can add up to 8 detached ADUs on one lot, plus interior conversions of up to 25% of existing units, subject to Fremont's standards.
What is the Preapproved ADU Plans program?
It's a Fremont program where architects and designers submit ADU plan sets for city pre-review. Homeowners who build from one of these preapproved plans can generally expect a faster plan-review timeline than a fully custom design.
