From 14,520 to 11,000
Lots between a quarter and a third of an acre that were out before can qualify now.
Lehi, Utah
Lehi lowered its lot size for backyard ADUs.
Lehi already allowed detached ADUs, but only on lots of 14,520 square feet or more. The city updated its code this summer, and the minimum is now the state's 11,000 square feet, which brings in a lot of new homeowners.
Rules updated, July 2026
What we confirmed for Lehi
Source: Deseret News, October 14, 2026; Herald Extra, July 15, 2026; Lehi City detached ADU guidance.
- Before
- Detached ADUs only on lots of 14,520 sq ft (a third of an acre) or more
- Now
- Lots of 11,000 sq ft or more with a single-family home
- Spacing
- A detached unit must be at least 6 ft from the main house
- Limit
- One ADU per lot
- Eligible lots
- Lehi's development director estimated eligible lots could grow by 20 percent or more
- Adopted
- July 2026
Not confirmed: Lehi's final size, setback and parking figures for each lot size. Confirm them with Lehi Planning.
What it means for you
What changes for Lehi homeowners.
Family or rental use
A parent suite or a long-term rental is exactly the case this change was written for.
One per lot
Only one ADU is allowed on a lot, so choose the plan that does the most for you.
Plans that fit
Compact floor plans for a Lehi backyard.
Small plans are easier to fit inside setbacks and cap parking at one space under 650 square feet. Open any plan for photos and the floor plan.
Final fit depends on your lot, utilities, the delivery route and the city's current standards. We confirm all of it in a lot review.
Budget the site work before you fall for a plan.
The home is only part of what a detached ADU costs. Sewer, water and power connections, trenching, the foundation and the finish work that joins the modules add up, and they depend on how far your lot is from the utilities. Taylorsville city staff told their council that utility connections alone could run 50 to 70 percent of the cost of a detached unit. We price the site and the utilities line by line in a lot review, before you commit to a plan.
How to plan the full budgetHow it works here
From your lot to move-in.
- Lot review. We check lot size, setbacks, utilities and the delivery route to your backyard.
- Choose a plan and finishes. Pick a floor plan and one of four finish series.
- City review. We help you prepare the plans and site information Lehi will want for approval and the building permit.
- Foundation and utilities. Site work happens on your lot while the home is built in the factory.
- Delivery and set. The home arrives by truck and is set by crane, then finished, connected and walked through with you.
Questions
Lehi ADU questions.
Does SB 284 apply to Lehi?
Yes. Lehi is covered by the state mandate, which requires a covered city to allow a detached ADU on a lot of 11,000 square feet or more that has a single-family home, as a permitted use. Cities can still set size, height, setback, owner-occupancy and rental rules within the limits of the law. Read the SB 284 guide.
How much parking does a detached ADU need?
A city cannot require more than one on-site space for a detached ADU under 650 square feet, or more than two for a unit of 650 square feet or larger.
Can I rent it out?
The state allows a city to require rentals of at least 90 consecutive days and to require the owner to live on the property. Check how Lehi applies those rules to your lot.
What if my lot is smaller than 11,000 square feet?
The state mandate does not reach it, but a city may choose to allow smaller lots. Ask Lehi Planning what applies to your parcel.
Does Stoneward work in Lehi?
Yes. Stoneward is based in American Fork and serves Utah County and the rest of the Wasatch Front. We run a lot review first and tell you plainly if a detached ADU does not fit.
General information, not legal advice. Cities can amend their ordinances, so confirm current rules with Lehi before you design or buy.
Own a lot in Lehi?
Send us your address. We will check the lot against Lehi's rules and tell you honestly whether a detached ADU fits.