Washington County · 106,288 residents
St. George ADU rules
St. George: internal ADUs allowed; detached ADUs allowed. Owner occupancy applies.
Internal ADU (inside the home)
Detached ADU (backyard building)
✓ Checked against city sources on September 24, 2026 See sources
St. George ADU rules at a glance
| Rule | Internal ADU (basement, attic, inside the home) | Detached ADU (backyard building) |
|---|---|---|
| Allowed? | Allowed | Allowed |
| Minimum lot | No minimum lot size: one ADU is allowed on any lot with a single-family home, and lots of 11,000 sq ft or more can have one attached plus one detached ADU. | No minimum lot size for a single detached ADU on a lot with a single-family home; lots of 11,000 sq ft or more may have one attached and one detached ADU. |
| Owner occupancy | An owner must live on the property, in either the main home or the ADU, and a deed restriction confirming owner occupancy must be recorded before the ADU is rented. | An owner must live on the property, in either the main home or the ADU, and a deed restriction confirming owner occupancy must be recorded before the ADU is rented. |
| Parking | One additional off-street parking space per ADU; tandem parking is not allowed, and garage or carport spaces lost to the ADU must be replaced if needed to keep the house compliant. | One additional off-street parking space per ADU; tandem parking is not allowed. |
| Size limits | Not yet verified — confirm with the city | Must be smaller than the gross floor area of the main home. |
| Height | Not yet verified — confirm with the city | Maximum 25 ft. |
| Setbacks | Entrances must use an existing door or be on the side or rear; basement stairs may extend up to 4 ft into a side or rear yard. | A one-story unit in the rear yard can be built up to the rear and side lot lines (0 ft). A unit in a front, street-side or side yard, or any two-story unit, must meet the house setbacks for the zone. Every detached unit needs 6 ft of separation from other structures and cannot sit over a utility easement without approval. |
| Zones | Allowed on any lot with a single-family home; lots of 11,000 sq ft or more (or inside the Downtown Boundary) may add a second ADU. | Allowed on any lot with a single-family home; up to two ADUs on lots of 11,000 sq ft or more (one attached, one detached) or within the Downtown Boundary. |
| Short-term rentals | Short-term rental of an ADU is not permitted. | Short-term rental of an ADU is not permitted. |
| Permit process | An accessory dwelling permit is required in addition to any building permits, along with a site plan, floor plans, owner verification and a rental dwelling business license. | An accessory dwelling permit plus building permits and a rental dwelling business license. Existing legal accessory buildings may be converted if they meet the ADU standards. A rear-yard unit shorter than the house does not have to match its design. |
What the St. George council decided
Recorded votes and actions on ADU rules, linked to the public meeting record on OpenUtah.
· City Council · Approved (5-0)
City Council approved Ordinance 2026-068 allowing one attached plus one detached ADU on lots of 11,000+ sq ft to comply with SB 284; vote from transcript.
Read the meeting record· St. George City Council · Approved
City Council approved Ordinance 2025-066 amending Title 10 regarding ADUs in multiple-family residential and mobile home zones.
Read the meeting record· St. George City Council · Approved
City Council approved Ordinance 2025-059 amending ADU standards in 10-17A-3 to allow two ADUs per lot within downtown boundaries.
Read the meeting record
State law: detached ADUs from October 1, 2026
St. George 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 St. George 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; St. George makes the decision.
- No numeric external minimum is recorded for St. George. The map keeps the statewide 11,000 sq ft external screen and shows the researched status (generally allowed) on the property report.
- "Likely" above 15,000 sq ft is this site's planning band for a large recorded lot. It is not a sentence in the St. George 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.
Sources
We link only to government sources and public meeting records. Codes change; confirm the current version with St. George before you apply.
- St. George City Council, Aug 20, 2026 agenda packet — Ordinance 2026-068 (Title 10-17A-3 ADU standards)
Staff report and full text of 10-17A-3 as amended: owner occupancy, parking, number of ADUs, 11,000 sq ft second-ADU rule, detached size/height/setback table, conversions.
- St. George City Council, Aug 20, 2026 — Ord. 2026-068 adoption (OpenCity)
Transcript and decision record: ADU amendment approved 5-0 on roll call.
- Utah S.B. 284 (2026), enrolled copy
Enacts Utah Code 10-21-304 (effective Oct 1, 2026): specified municipalities must permit a detached ADU on single-family lots of 11,000 sq ft or more; defines 'specified municipality'.
- Utah Code 10-2-301 — Classification of municipalities
City class population thresholds.
- Utah Code 17-60-104 — Classification of counties
County class population thresholds.
- U.S. Census Bureau Vintage 2024 subcounty population estimates
July 1, 2024 population estimates for Utah places and counties.
- Official St. George website
Common St. George ADU questions
Can you build an ADU in St. George?
St. George: internal ADUs allowed; detached ADUs allowed. Owner occupancy applies. This is planning guidance, not a permit. Confirm the zone on your parcel with St. George.
What lot size does St. George require for an ADU?
Internal ADU: No minimum lot size: one ADU is allowed on any lot with a single-family home, and lots of 11,000 sq ft or more can have one attached plus one detached ADU. Detached ADU: No minimum lot size for a single detached ADU on a lot with a single-family home; lots of 11,000 sq ft or more may have one attached and one detached ADU.
Does St. George require the owner to live on the property?
Internal ADU: An owner must live on the property, in either the main home or the ADU, and a deed restriction confirming owner occupancy must be recorded before the ADU is rented. Detached ADU: An owner must live on the property, in either the main home or the ADU, and a deed restriction confirming owner occupancy must be recorded before the ADU is rented.
How much parking does a St. George ADU need?
Internal ADU: One additional off-street parking space per ADU; tandem parking is not allowed, and garage or carport spaces lost to the ADU must be replaced if needed to keep the house compliant. Detached ADU: One additional off-street parking space per ADU; tandem parking is not allowed.
Can an ADU in St. George be a short-term rental?
Internal ADU: Short-term rental of an ADU is not permitted. Detached ADU: Short-term rental of an ADU is not permitted.
What does it cost to build an ADU in St. George?
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 St. George?
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 St. George 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 St. George lot?
Free, no obligation. We review your parcel against these rules and, if you want, introduce independent design and construction partners. Partners may pay us for referrals.
Utah ADU Builder provides educational planning guidance. This page is not legal advice and not a permit. Population: U.S. Census Bureau population estimate (2024). Editorial standards.