Salt Lake County, UT Building Setbacks & Zoning: Lot Coverage Limits (2026)

Section 19.15.080 is two sentences long, and both do work. The first says lot coverage maximums are "as outlined per each zone", so the percentage you can build is whatever your zone's own chapter sets. The second applies that limit to two kinds of project: any addition to an existing building, and construction of a detached ADU. Both must follow section 19.15.050 on setbacks and cannot exceed the allowable lot or rear yard coverage standard of the underlying zone, except as section 19.15.050 provides.

In the R-1 single-family zones (R-1-3 through R-1-43), the standard that matters is section 19.14.070: no accessory building or group of accessory buildings shall cover more than twenty-five percent of the rear yard. A detached ADU competes for that rear yard ceiling with any garage, shed or workshop already behind the house. The A, Forestry and PC zones carry their own coverage rules in their own chapters, which section 19.15.080 incorporates by reference.

Coverage is also a gate on eligibility. Section 19.15.030(B) says an ADU is never permitted on a lot that cannot satisfy parking, setback or lot coverage requirements. Section 19.15.030(A) sets the minimum lot at six thousand square feet for an internal ADU and seven thousand square feet for a detached ADU, with six thousand allowed in a PC Zone where the county has approved design standards.

The setback rules that sit beside coverage shape where a detached ADU can go. Rear yard setbacks are a minimum of ten feet, the unit must be at least six feet from the main dwelling, and where a public utility easement is wider than the required setback, the easement boundary becomes the minimum. A detached ADU cannot sit in a front or corner lot side yard unless the lot is at least one acre and the unit is at least thirty feet from the front lot line (section 19.15.110(H)). New detached ADUs must also be offset ten feet or more from the front facade of the main dwelling (section 19.15.110(I)).

Height ties into the same footprint math. A detached ADU with a rear or side yard setback under ten feet tops out at twenty feet, while one set back ten feet or more can match the height of the primary dwelling (section 19.15.070). Only one ADU, internal or detached, is allowed per lot (section 19.15.100).