Weber County · 38,785 residents
Roy ADU rules
Roy: internal ADUs allowed (lot 6,000+ sq ft); 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.
Internal ADU (inside the home)
Detached ADU (backyard building)
Not yet fully verified · last reviewed September 7, 2026 See sources
Roy ADU rules at a glance
| Rule | Internal ADU (basement, attic, inside the home) | Detached ADU (backyard building) |
|---|---|---|
| Allowed? | Allowed | Not generally allowed |
| Minimum lot | 6,000 sq ft. Statewide statute includes a small-lot pathway around 6,000 sq ft for many internal ADUs — confirm how Roy applies it on your zone. | 11,000 sq ft. S.B. 284 statewide detached floor for specified municipalities: roughly 11,000 sq ft on qualifying single-family lots (operative Oct 1, 2026). Local detached eligibility is limited or prohibited until a compliant ordinance is in force. |
| Owner occupancy | Owner occupancy is expected for the primary home or ADU. | Not yet verified — confirm with the city |
| Permit process | Rental dwelling license typically required for rented units; confirm current internal ADU registration/notice steps with Planning. | Not yet verified — confirm with the city |
State law: detached ADUs from October 1, 2026
Roy 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 Roy 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; Roy makes the decision.
- Because external ADUs are not typical in the Roy 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 Roy 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 Roy
Roy adopted an internal-ADU framework covering permitted uses and parking. Later council material discusses garage space as part of an internal conversion, so the project need not begin and end with a basement concept. We can help check the current code and how replacement parking affects a garage-based plan.
Bring these to your review
- Basement and garage dimensions
- Parking retained after conversion
- Existing permits and proposed occupancy
The question to resolve first
Could a garage or basement conversion satisfy Roy’s current internal-ADU requirements?
Sources
We link only to government sources and public meeting records. Codes change; confirm the current version with Roy before you apply.
- Roy City Council minutes, July 20, 2021
Minutes record approval of Ordinance 21-11; later amendments require verification
- Roy council material — internal ADUs and garage space
Discussion record, not proof of a later ordinance adoption
- Utah S.B. 284 (2026), enrolled bill
Statewide detached-ADU requirements for specified municipalities, operative October 1, 2026.
- Official Roy website
Common Roy ADU questions
Can you build an ADU in Roy?
Roy: internal ADUs allowed (lot 6,000+ sq ft); 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. This is planning guidance, not a permit. Confirm the zone on your parcel with Roy.
What lot size does Roy require for an ADU?
Internal ADU: 6,000 sq ft minimum. Statewide statute includes a small-lot pathway around 6,000 sq ft for many internal ADUs — confirm how Roy applies it on your zone. Detached ADU: 11,000 sq ft minimum. S.B. 284 statewide detached floor for specified municipalities: roughly 11,000 sq ft on qualifying single-family lots (operative Oct 1, 2026). Local detached eligibility is limited or prohibited until a compliant ordinance is in force.
Does Roy require the owner to live on the property?
Internal ADU: Owner occupancy is expected for the primary home or ADU. Detached ADU: Not yet verified — confirm with the city.
What does it cost to build an ADU in Roy?
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 Roy?
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 Roy 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 Roy 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.