Utah County · 37,268 residents
American Fork ADU rules
American Fork: internal ADUs allowed; detached ADUs are not generally allowed today. Beginning October 1, 2026, state law (S.B. 284) requires the city to permit a detached ADU on qualifying single-family lots of 11,000 sq ft or more. Owner occupancy applies.
Internal ADU (inside the home)
Detached ADU (backyard building)
Not yet fully verified · last reviewed September 7, 2026 See sources
American Fork ADU rules at a glance
| Rule | Internal ADU (basement, attic, inside the home) | Detached ADU (backyard building) |
|---|---|---|
| Allowed? | Allowed | Not generally allowed |
| Minimum lot | Not yet verified — confirm with the city | 11,000 sq ft |
| Owner occupancy | Required (owner in main or apartment) | Not yet verified — confirm with the city |
| Parking | 2 off-street spaces in addition to 2 required for the single-family home (tandem in driveway may count); lot that cannot meet parking cannot have accessory apartment | Not yet verified — confirm with the city |
| Size limits | No explicit size cap in ADU section summaries | Not yet verified — confirm with the city |
| Setbacks | Dedicated entrance on side or rear; interior access to main living area must be maintained | Not yet verified — confirm with the city |
| Zones | All single-family residential zones subject to §17.5.134 | Not yet verified — confirm with the city |
| Permit process | Permitted use with conditions of §17.5.134; landlord registration rules vary by zone | Public hearings Sep 16, 2026 Planning Commission on definitions + Detached Accessory Dwelling Units section |
State law: detached ADUs from October 1, 2026
American Fork is a “specified municipality” under Utah S.B. 284. Beginning October 1, 2026, it must permit one detached ADU as a permitted use on a lot of 11,000 sq ft or more that has a detached single-family home. The city can still apply setbacks, height, design, owner-occupancy and limited parking rules, and it may allow detached ADUs on smaller lots. How the state ADU laws work.
How our property map screens American Fork lots
The map colors parcels using the rules on this page and the recorded lot size. A color is a planning screen, not a permit; American Fork makes the decision.
- Because external ADUs are not typical in the American Fork research, the map does not mark a new external ADU as likely there.
- "Likely" above 15,000 sq ft is this site's planning band for a large recorded lot. It is not a sentence in the American Fork code. Owner occupancy, parking, setbacks, zones, and HOA rules below still have to be checked.
Planned communities, PRDs and PUDs
Reviewed on September 22, 2026 against this city's research file, its published ADU page where one was found, and Utah meeting packets. No adopted sentence was confirmed that allows or bans an ADU in every PUD, PRD, PRUD, or planned community. If the assessor class or subdivision name says PUD, PRD, PRUD, planned unit development, planned residential development, planned community, resort community, or master planned community, the map keeps that lot highly unlikely regardless of size. A plat, CC&Rs, or development agreement can still prohibit an ADU where the zone allows one.
Planning notes for American Fork
American Fork emphasizes complete applications: show the entire lot, existing house, all accessory structures, setbacks and public utility easements. A good site plan is useful even for a basement conversion because parking and access still need to work. Treat the archived §17.5.134 apartment handout as a reference to reconcile with current rules, not a substitute for that check.
Bring these to your review
- One scaled plan showing every existing and proposed structure
- Easements, driveway and parking dimensions
- Floor plan and description of internal, attached or detached work
The question to resolve first
Which current apartment or detached-ADU provisions apply to this parcel and application date?
Sources
We link only to government sources and public meeting records. Codes change; confirm the current version with American Fork before you apply.
- American Fork Building Department — submittal requirements
Published city guidance
- American Fork §17.5.134 — accessory apartments, archived city copy
Historical code copy; confirm current amendments
- Utah S.B. 284 (2026), enrolled bill
Statewide detached-ADU requirements for specified municipalities, operative October 1, 2026.
- Official American Fork website
Common American Fork ADU questions
Can you build an ADU in American Fork?
American Fork: internal ADUs allowed; detached ADUs are not generally allowed today. Beginning October 1, 2026, state law (S.B. 284) requires the city to permit a detached ADU on qualifying single-family lots of 11,000 sq ft or more. Owner occupancy applies. This is planning guidance, not a permit. Confirm the zone on your parcel with American Fork.
What lot size does American Fork require for an ADU?
Internal ADU: Not yet verified — confirm with the city. Detached ADU: 11,000 sq ft minimum.
Does American Fork require the owner to live on the property?
Internal ADU: Required (owner in main or apartment). Detached ADU: Not yet verified — confirm with the city.
How much parking does a American Fork ADU need?
Internal ADU: 2 off-street spaces in addition to 2 required for the single-family home (tandem in driveway may count); lot that cannot meet parking cannot have accessory apartment. Detached ADU: Not yet verified — confirm with the city.
What does it cost to build an ADU in American Fork?
Wasatch Front planning bands are often about $55,000–$145,000 for an internal suite, $70,000–$175,000 for a garage conversion, and $95,000–$250,000 or more for a new detached unit, before unusual site work. These are planning ranges, not bids.
Can an HOA block an ADU in American Fork?
City approval does not override CC&Rs or plat notes. Read the HOA documents and your subdivision plat before you design. A private restriction can stop a unit the city would otherwise allow.
Before you design: general checks for any Utah ADU
General planning advice, not American Fork code.
- Confirm the zoning district on the city zoning map. The county assessor’s “residential” class is not zoning.
- Read your HOA CC&Rs and subdivision plat notes; private restrictions can block a unit the city allows.
- Sketch existing and proposed parking. Driveway geometry and access often decide what fits.
- Ask early about sewer, water and electrical capacity; utilities can force a redesign.
- Expanding a building’s footprint usually triggers full setback and height rules.
Nearby city ADU rules
Want to know what fits on your American Fork lot?
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Utah ADU Builder provides educational planning guidance. This page is not legal advice and not a permit. Population: UGRC POPLASTESTIMATE / Census-derived municipal estimates (manual fill where UGRC blank). Editorial standards.