General Contractor in Lehi, Utah

For an internal ADU, Section 26.030 of the Lehi City Development Code sets conditions that include these, in its own order.

• One ADU in an owner-occupied single-family detached home, with a permit from the Planning Division before construction and an active ADU license while the unit is rented and in use
• The owner living in the dwelling that holds the ADU, with a recorded affidavit that the primary dwelling will be owner occupied
• A single-family appearance for the structure, with no outside evidence that more than one family lives there
• One off-street parking stall of at least 9 by 20 feet, separate from and not in tandem with the home's parking
• A lighted walkway from the parking area to the ADU entrance
• A location outside the areas on the ADU Restricted Area Map, on a lot of at least 6,000 square feet
• A physical connection, such as a locking door, between the home and the ADU, so the space can rejoin the home if the unit is discontinued
• A building permit from the Building and Inspection Department before construction, with the unit built to the city's adopted building codes
• One ADU in service per lot, and never an active ADU and an active short-term rental permit at the same time

For a detached ADU, Section 26.040 adds conditions that include these, in its own order.

• A lot of at least 11,000 square feet
• A unit with less finished living area than the home, set beside or behind it, at least 6 feet away, on a permanent foundation
• A separate city-assigned address, the home's address followed by ½, displayed clearly from the street
• Utility services connected to the primary dwelling, and all-weather access at least 12 feet wide for emergency vehicles and utilities
• Two off-street parking stalls for a unit larger than 650 square feet, or one for a smaller unit, in addition to the home's parking
• For a unit built or converted from a building permitted after December 31, 2020, placement within 5 feet of a side or rear property line only when the wall within 5 feet has no windows or two small opaque windows of 2 square feet or less, a 10-foot setback for a one-story unit up to 20 feet tall with larger windows, and the home's setbacks for a two-story unit or one taller than 20 feet
• For those units, a height no greater than the home's, up to 35 feet, and at least 300 square feet of living space

Section 26.040, last amended July 14, 2026, sets the 11,000-square-foot minimum lot listed above. Lehi's Table 05-030-A, the table of uses for agriculture and residential districts, last amended February 11, 2025, still states that a detached ADU requires a lot of at least 15,000 square feet and may require a conditional use permit based on year built. We confirm the lot size and the approval path for your property with Lehi's Planning Division during preconstruction.

Utah's ADU statutes apply in Lehi as well, as our ADU page explains.

Sources: Lehi City Development Code, Chapter 26; Table 05-030-A; Utah Code 10-21-303; Utah Code 10-21-304. Section 26.070 ties the 35-foot maximum to lots of 22,000 square feet.

Utah ADU Law and Building Code