ADU Rules in Salt Lake City, UT (2026)
ADU rules, permit requirements, size limits, and fees for Salt Lake City, UT. Source-cited from official municipal code.
Yes, ADUs are allowed in Salt Lake City, UT.
Salt Lake City, UT permits accessory dwelling units (ADUs) on residential properties. ADUs — also called granny flats, in-law units, backyard cottages, or secondary suites — are secondary housing units on a single-family or multifamily lot. State and local law actively preempts local restrictions, making ADU approval a streamlined ministerial process. In Salt Lake City, the Salt Lake City Building Services handles ADU permit applications. Below you will find the current size limits, setbacks, fees, and timeline for building an ADU in Salt Lake City.
ADU Size Limits
ADU Size Limits in Salt Lake City: Detached ADU: up to 1000 sq ft (max height: 25 feet). Attached ADU: No greater than 50% of primary dwelling floor area, up to 1,000 sqft. Salt Lake City Code Title 21A limits ADUs to 1,000 sqft maximum. Utah does not use the JADU designation from California law. Internal ADUs (attached/within dwelling) are permitted by-right statewide under SB 174. Detached ADUs are also allowed in SLC residential zones with building permit.
| Type | Max Size | Max Height |
|---|---|---|
| Detached ADU | 1000 sq ft | 25 feet |
| Attached ADU | No greater than 50% of primary dwelling floor area, up to 1,000 sqft | Per zone height limit |
Permit Fees
ADU Permit Fees in Salt Lake City: Plan check fee: $300-$1,500. Building permit fee: Based on construction valuation — typically $800-$3,500. Impact fees: Water/sewer impact fees may apply — Salt Lake City Public Utilities charges connection fees. School fees: None or N/A. Total estimated permit cost: $1,500-$6,000 total permit fees for typical ADU. Salt Lake City Public Utilities water/sewer impact fees for ADU connections. Fee schedule: https://www.slc.gov/planning/permits/
| Fee Type | Amount |
|---|---|
| Plan Check | $300-$1,500 |
| Building Permit | Based on construction valuation — typically $800-$3,500 |
| Impact Fees | Water/sewer impact fees may apply — Salt Lake City Public Utilities charges connection fees |
| School Fees | None |
| Total Estimate | $1,500-$6,000 total permit fees for typical ADU |
Permit Timeline
Salt Lake City ADU Permit Timeline: Salt Lake City Division of Planning processes ADU permits. Standard ADU permit: 4-8 weeks plan review. Internal ADUs typically faster (ministerial approval per SB 174). Construction typically 3-9 months. Apply through the Salt Lake City Building Services online permit portal. Phone: (801) 535-6000.
Setback Requirements
ADU Setback Requirements in Salt Lake City: Front setback: Same as zone standard. Side setback: 5 feet. Rear setback: 10 feet. ADUs must comply with zone setback standards. Minimum 5 ft side and 10 ft rear setbacks for detached ADUs. Garage conversions to ADU may have reduced setbacks if converting existing structure. Salt Lake City Code Title 21A.
Parking Requirements
Parking Requirements: Utah SB 174 and local code: 1 parking space per ADU unit in most residential zones. No additional parking required for internal ADUs under SB 174. Salt Lake City reduces parking requirements near TRAX light rail and UTA bus rapid transit.
Restrictions & Requirements
- ADU must comply with Salt Lake City Code Title 21A setback and lot coverage standards
- ADU cannot be sold separately from principal dwelling
- Short-term rental of ADU requires SLC STR license
- ADU must have permanent foundation
- External ADU design should be architecturally compatible with primary structure
- ADU access must maintain required parking and circulation on lot
How Many ADUs Are Allowed?
Number of ADUs Allowed in Salt Lake City: Single-family lots: 1 ADU per single-family lot (internal ADU required by state law; detached ADU also allowed in most SLC residential zones). Multifamily properties: ADUs and additional units permitted in RMF zones per Salt Lake City Code. Utah SB 174 requires at least 1 internal ADU per single-family lot by-right. SLC local code allows detached ADUs in addition, giving single-family lots up to 2 additional dwelling units in some configurations.
Single-Family Lots
1 ADU per single-family lot (internal ADU required by state law; detached ADU also allowed in most SLC residential zones)
Multifamily Properties
ADUs and additional units permitted in RMF zones per Salt Lake City Code
State Law & Preemption
State Preemption: Utah Senate Bill 174 (effective May 5, 2021) requires all Utah municipalities to allow at least one internal ADU (within or attached to the primary dwelling) by-right on all single-family lots. Municipalities cannot require a conditional use permit for internal ADUs. Salt Lake City complies with state law and has also expanded local ADU provisions to include detached ADUs in many zones. Subsequent legislation including HB 572 (2024) has further expanded ADU incentives statewide.
Historic District Considerations
Historic District Requirements: Salt Lake City has 9 historic districts where additional design review may be required for ADU construction. Design review approval is required before obtaining a building permit for properties in historic overlay zones. Salt Lake City has multiple Historic Preservation Overlay (H) districts including The Avenues, Capitol Hill, South Temple, and 9th and 9th. Certificate of Appropriateness required for exterior alterations in historic districts. Salt Lake City Historic Landmark Commission administers review. Look up historic district boundaries at: https://www.slc.gov/planning/historic-preservation/
Frequently Asked Questions
Can I build an ADU in Salt Lake City?
Yes. Salt Lake City, UT allows accessory dwelling units. On a single-family lot you can build 1 ADU per single-family lot (internal ADU required by state law; detached ADU also allowed in most SLC residential zones).
How big can an ADU be in Salt Lake City?
The maximum size for a detached ADU in Salt Lake City is 1,000 square feet.
How long does it take to get an ADU permit in Salt Lake City?
The typical ADU permit timeline in Salt Lake City is Salt Lake City Division of Planning processes ADU permits. Standard ADU permit: 4-8 weeks plan review. Internal ADUs typically faster (ministerial approval per SB 174). Construction typically 3-9 months.. Total estimated permit fees are $1,500-$6,000 total permit fees for typical ADU.
Do I need extra parking for an ADU in Salt Lake City?
No, Salt Lake City does not require additional parking for ADUs.
Do I have to live on-site to have an ADU in Salt Lake City?
No, owner-occupancy is not required for ADUs in Salt Lake City.
Source: Salt Lake City Code Title 21A; Utah Code Section 10-9a-534 (SB 174 ADU requirements). Last verified April 5, 2026. View source