On October 1, 2026, 11,000 Square Feet Decides Your St. George ADU
Service Area: St. George, UT
On October 1, 2026, Utah Code section 10-21-304 takes effect and St. George loses the ability to deny a detached ADU on a qualifying lot. If you have been putting off the backyard-unit question, that is the date the answer changes.
Apex Drafting draws custom house plans, ADU sets and permit-ready documents for St. George and Washington County. Statutes below are cited by number, and where the public data disagrees, we say so.
The growth here is migration, not birth rates
Washington County reached 209,129 residents as of July 1, 2025, up 4,751 people (2.32%). Composition matters more than the total: 4,146 of those came from net migration, about 87%, against 605 from natural increase. Migration-driven growth needs finished, permit-ready housing now, drawn to a code the arriving owner has never read.
The county was the third-largest contributor to Utah's 2025 population growth, 10.7% of the statewide total, behind only Utah and Salt Lake counties. In 2024 the city issued 2,515 building permits valued at $481.5 million, about 800 of them single-family, against 2,419 permits at $328.5 million in 2023: a 47% jump in valuation in one year. County-wide, 3,152 new private housing units were authorized.
One caveat nobody else here publishes: the long-run forecast was revised down, sharply. The late-2025 projection has Washington County at 384,339 by 2065, up 175,255 (about 84%), against an early-2022 projection of roughly 155% growth by 2060. Near-term demand is real, but the 40-year story is more moderate than the version still quoted around town.
What a St. George house is worth depends on who you ask
The two largest public sources disagree on direction, and picking the flattering one would be the easy move. Redfin reports a $539,000 median sale price for the three months ending May 2026, up 4.7% year over year, at $260 per square foot (down 4.6%). Zillow reports a typical home value of $506,835, down 5.3% over the past year.
The two measures are built differently and pull apart when new construction is a large share of closings, so budget from your own scope and the $260 per square foot reference.
Apex Drafting is a remote studio. We do not have a St. George storefront and will not invent one. What matters is whether the person drawing your set knows which code section governs your lot.
Utah SB 284 takes effect October 1, 2026
SB 284 (2026 General Session, "Local Land and Water Modifications") created Utah Code section 10-21-304, effective October 1, 2026. Municipalities of 5,000 or more residents must permit a detached accessory dwelling unit on any lot of 11,000 square feet or larger containing a single-family dwelling where single-family is a permitted use.
- A city cannot require a conditional-use permit for a qualifying detached ADU. That removes the discretionary hearing, where most backyard-unit projects historically died.
- A city cannot impose a maximum size other than capping the unit at the size of the primary home.
- Setbacks, height, parking, owner-occupancy and design standards remain local. The state sets a floor on whether you may build. The city still controls how.
- Cities without a conforming ADU policy must adopt one by October 2026, so the local rulebook is in motion.
HB 82 already made internal ADUs a right in 2021
The detached mandate is new. The internal one is not. HB 82 (2021), codified at Utah Code 10-9a-530 and effective October 1, 2021, made internal ADUs a permitted use by right in most residential zones statewide, with no conditional-use permit or discretionary hearing. It removed the statewide owner-occupancy mandate while letting cities keep their own, and defined internal ADUs as rentals of 30 days or more, which excludes nightly rentals.
Lot size decides which path you are on. Under 11,000 square feet, the internal route under 10-9a-530 is what exists. At 11,000 or more, 10-21-304 opens the detached route.
St. George City Code section 10-17A-3: what the city requires
State law sets the floor. St. George City Code section 10-17A-3 governs the rest, and it was amended by Ordinance 2025-059, codified in August 2025. A plan drawn against the pre-2025 text is drawn against a code that no longer exists. Confirmed in the code text itself:
- An ADU is a subordinate residential living area within a single-family dwelling or in a detached building on the same lot.
- Owner-occupancy is required. The owner must live on the property, in the primary dwelling or the ADU.
- Short-term rental of an ADU is not permitted.
- One ADU or guesthouse per lot, except within the Downtown Boundary, where two ADUs per lot are allowed.
A guesthouse is a different use under a different section. Under section 10-17A-7 it runs a minimum of 150 square feet and a maximum of 400 square feet, only on lots of 8,000 square feet or larger with an existing owner-occupied single-family dwelling, with an exception path for smaller lots in PD zones. For a small detached space for family, that is often the shorter road.
On the numbers we are not printing: the code also sets ADU size and setback standards, and figures for those circulate widely on local real estate blogs. Those versions trace to a blog, not the post-Ordinance 2025-059 code text, so we do not publish them. Apex confirms the current figures with St. George planning before drafting begins.
Working on a St. George, UT project right now?
Send us the lot and what you want to build. We'll confirm which local rules apply to your parcel and come back with a firm number, at no cost.
Little Valley and Desert Color are two different drafting problems
Writing to "St. George" as one market is how the thin pages on this topic get written. The subdivisions do not behave alike.
Little Valley closed 227 homes over the trailing twelve months at medians between $695,000 and $940,000, dominated by custom builders. That is the custom-plan submarket here: larger lots, buyers already committed to a one-off house, and enough price headroom that a plan drawn around the lot pays for itself. Many Little Valley lots also clear the 11,000 square foot line 10-21-304 keys on, making a detached ADU a live conversation there on October 1.
Desert Color is the opposite geometry: a 2,058 square foot median home on roughly a 0.09-acre lot, every home built 2020 or later, average build year 2024. A 0.09-acre lot is about 3,900 square feet, so most Desert Color lots will not qualify for the state-mandated detached ADU. Worth knowing before you pay anyone to draw one. The internal path under 10-9a-530 may still be open.
Where the demand actually sits
About 800 single-family permits a year, an ADU mandate in October, and a custom-builder submarket point demand at three services.
ADU Plans & Design
Section 10-21-304 opens the detached path on October 1 for lots of 11,000 square feet or larger; 10-9a-530 already covers internal units. Which applies is what we settle first.
ADU Plans & DesignCustom House Plans
Little Valley closed 227 homes in a year at $695,000 to $940,000 medians in a custom-builder market. That is the profile where a plan drawn around the lot beats one adapted to it.
Custom House PlansPermit-Ready Drawings & As-Builts
St. George processed 2,515 permits in 2024. A complete, correctly formatted set is the difference between one review cycle and three.
Permit-Ready Drawings & As-BuiltsStock house plans start at $799. Worth stating plainly, because most of this market publishes no prices at all and the local published range we can point to for stock plans runs from $2,236 to $4,562. If a stock plan fits your lot, there is no reason to pay a multiple of that. If it does not fit, we say so. Additions and remodels, 3D renderings, energy-efficient design and multigenerational design come out of the same studio, with numbers on the pricing page.
What happens when the drawings hit the counter
Every competing page here is a service menu; none explains how submittal works, which is the part that costs people weeks. The City of St. George takes plan submittals through the CityInspect Portal. Washington County accepts building permit applications electronically only, so a paper set is a non-starter on an unincorporated-county project. Washington City publishes its own separate residential submittal requirements. Three jurisdictions, three intake processes, and we format the set for the office that will open it. The guide on permit-ready house plans covers what a complete set contains; the full menu is under services.
St. George drafting questions we get
What does Utah SB 284 change for a St. George ADU on October 1, 2026?
SB 284 created Utah Code section 10-21-304, effective October 1, 2026. Municipalities of 5,000 or more residents must permit a detached ADU on any lot of 11,000 square feet or larger holding a single-family dwelling. No conditional-use permit, and no maximum size other than the size of the primary home. Setbacks, height, parking and owner-occupancy stay local.
Does St. George require the owner to live on the property with an ADU?
Yes. City Code section 10-17A-3 requires the owner to live on the property, in the primary dwelling or the ADU. SB 284 does not remove that, because owner-occupancy is a standard the state leaves to the city.
Can I rent a St. George ADU on Airbnb or VRBO?
No. Short-term rental of an ADU is not permitted under section 10-17A-3. If nightly rental income is the reason for the project, an ADU is the wrong instrument.
What is the difference between an ADU and a guesthouse in St. George?
Separate uses under separate sections. A guesthouse under 10-17A-7 runs 150 square feet minimum to 400 square feet maximum, only on lots of 8,000 square feet or larger with an existing owner-occupied single-family dwelling. An ADU under 10-17A-3 sits inside the dwelling or in a detached building on the same lot. One of either per lot, except within the Downtown Boundary, where two ADUs are allowed.
Will a Desert Color lot qualify for a detached ADU under SB 284?
Usually not. Desert Color lots run around 0.09 acres, roughly 3,900 square feet, well under the 11,000 square foot threshold. The internal path under Utah Code 10-9a-530 may still be open, but any proposal leaning on SB 284 for a typical Desert Color lot is wrong.
Utah coverage
St. George is our covered Utah metro. The statewide picture, including how HB 82 and SB 284 apply outside Washington County, is on the Utah hub.
The rest of southern Utah we draft for
Each is a separate jurisdiction with its own counter, and the state mandate applies municipality by municipality.
Cedar City earns its own mention: Iron County reached 69,939 residents in 2025, up 2,042 (3.01%), tied with Tooele as the fastest-growing county in Utah, about 80% of it net migration.
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