Salt Lake City has become one of the more ADU-friendly cities in Utah, with zoning rules that allow homeowners to add secondary units across a wide range of residential neighborhoods. An accessory dwelling unit, commonly called a granny flat, in-law suite, backyard cottage, or carriage house, is a self-contained secondary home on the same lot as a primary residence. Landlords and homeowners build them to generate rental income, house family members, or increase property value. This guide covers everything you need to know before breaking ground, from zoning and size limits to permits, costs, and rental rules.
Where ADUs are allowed in Salt Lake City
ADUs are permitted in single-family and certain multi-family residential zoning districts across the city. Before doing anything else, confirm your parcel's zoning designation. The Salt Lake City Building Services ADU page includes a zoning lookup tool that makes this check straightforward.
Only one ADU is allowed per lot. The unit must be fully self-contained, with its own kitchen, bathroom, and sleeping area. It cannot be used as a short-term rental without a separate city license, which is a distinct approval from the ADU permit itself.
Salt Lake City expanded its list of eligible zoning districts through ordinance updates in 2022 and 2023, so properties that weren't eligible a few years ago may qualify now. If you were told no in the past, it's worth checking again under the current rules.
Types of ADUs allowed
Salt Lake City recognizes several ADU configurations:
Detached ADUs are standalone structures built in a backyard or side yard, separate from the main house. These tend to offer the most privacy for tenants and the most flexibility in design.
Attached ADUs are additions physically connected to the primary residence but with a separate entrance and self-contained living space.
Internal ADUs are units carved from existing space inside the home, such as a finished basement, an attic conversion, or a converted garage. Because they don't expand the building footprint, they face fewer lot-coverage restrictions.
Each type goes through the same general permit process, though internal conversions often have a simpler path because they don't trigger the same site and setback review as new construction.
Size limits, setbacks, and height rules
Salt Lake City caps detached ADU floor area at 1,000 square feet. That's the ceiling, but your actual buildable envelope may be smaller once lot coverage limits and setbacks are applied. A compact lot with existing structures can eat into that allowance quickly.
Setback requirements vary by zone. As a general rule, detached ADUs must sit at least four to six feet from rear and side property lines. Height limits for detached accessory structures typically fall between 20 and 24 feet, depending on the zoning district. Specific numbers for your zone are in the Salt Lake City ADU Handbook, and it's worth checking them early in your planning process rather than designing to the maximum and then discovering you're over the limit.
Internal ADUs must meet the same habitability standards as detached units, including ceiling height, natural light, ventilation, and egress requirements, but they don't add to the building's footprint, so lot coverage isn't usually the constraint.
Owner-occupancy requirements
Salt Lake City requires owner-occupancy for most ADU permits. Either the primary residence or the ADU must be the owner's primary home. You can rent one and live in the other, but you can't own the property as a pure investment and rent out both units under a standard ADU approval.
The city clarified its enforcement language during the 2023 ordinance updates, but the underlying requirement didn't go away. If your situation is unusual, such as a trust-held property or an LLC ownership structure, confirm your eligibility directly with the Planning Division before investing in design work.
The permit process, step by step
Getting an ADU permitted in Salt Lake City follows three main stages.
Pre-application review. Confirm zoning eligibility, determine whether your project fits a city-approved standard plan, and identify whether you'll need a conditional use permit. The city released a library of pre-approved standard plans that have already cleared design review. Using one of these can cut weeks off your timeline.
Application and plan review. Submit site plans, floor plans, and required documentation to Salt Lake City Building Services. Custom designs may also require Planning Division review. Some ADU configurations still require a conditional use permit, which triggers a public hearing before the Planning Commission. Approval at that hearing isn't automatic, so factor the time and uncertainty into your schedule.
Building permit and inspections. Once plans are approved, you pull a building permit and proceed under standard construction inspection requirements. Don't start any work before the permit is issued. Permit fees are based on the project's construction value; check the current schedule with Building Services directly, as fees update periodically.
Parking requirements
Most Salt Lake City residential zones require one off-street parking space per ADU. Properties within a qualifying distance of a TRAX light rail stop or UTA bus route may be eligible for a parking waiver. The city has gradually loosened parking requirements near transit corridors, so if your property is close to a transit line, confirm current waiver eligibility through the Planning Division before designing a new space into your site plan.
How Utah state law affects Salt Lake City ADUs
Utah has passed state legislation encouraging ADU development statewide, and Salt Lake City's local code must stay consistent with those standards. State law addresses minimum lot sizes, permissible setbacks, and other baseline rules. Where city regulations are stricter than state minimums, city rules apply. Where state law preempts local restrictions, Salt Lake City has had to bring its code into alignment.
This interplay has generally moved in a direction that makes ADUs easier to build, not harder. If you want to track the legislative picture, the Utah State Legislature website is the best source for current statutes affecting ADU development across the state.
Renting out your ADU
Long-term rentals of 30 days or more are permitted under a standard ADU approval, provided the owner-occupancy requirement is met. Short-term rentals through platforms like Airbnb require a separate short-term rental license from the city. Salt Lake City enforces this distinction, so don't assume your ADU permit covers vacation-style rentals.
If you're renting your ADU, review your insurance coverage before you put a tenant in. A standard homeowner's policy typically won't cover tenant-related liability or loss of rental income. Landlords renting ADUs in Utah should look into dedicated landlord coverage; Steadily's Utah landlord insurance page is a useful starting point for comparing options.
HOA considerations
If your property is governed by a homeowners association, the HOA's covenants, conditions, and restrictions may impose limits on ADU construction that go beyond city zoning rules. Some HOAs prohibit detached structures, restrict exterior modifications, or require architectural approval before you can build. City zoning permission doesn't override HOA rules, so review your CC&Rs before committing to a design. If there's a conflict, you may need to seek a variance from the HOA board or consult an attorney about your options.
Costs and financial planning
ADU costs in Salt Lake City vary considerably depending on type and scope. An internal basement conversion generally costs less than a detached new-build. Recent projects in the area have ranged from roughly $150,000 for simpler conversions to well over $300,000 for detached units with higher-end finishes and challenging site conditions. Budget for permits, design fees or standard plan costs, construction, utility connections (which may require separate meters), and a contingency for surprises.
Financing options include home equity lines of credit, construction loans, and renovation mortgages. The city doesn't currently offer direct incentives for ADU construction, though Utah Housing Corporation programs may apply depending on your income and project type.
When choosing a contractor, prioritize someone with direct Salt Lake City ADU experience. Familiarity with the local permit process and the city's standard plan library can save meaningful time. Verify any contractor's license through the Utah Division of Occupational and Professional Licensing.
Frequently asked questions
Can I build an ADU if I don't live on the property?
Generally, no. Salt Lake City's owner-occupancy requirement means either the main house or the ADU must be your primary residence. Exceptions are limited; if your ownership structure is unusual, confirm eligibility with the Planning Division before investing in plans.
Does Salt Lake City allow ADUs in all residential zones?
Not all zones qualify. Single-family residential zones are typically eligible, but you need to verify your specific parcel. Use the city's ADU information page to check your address.
What's the maximum size for a detached ADU?
1,000 square feet, subject to your lot's coverage limits. Setbacks and existing structures may reduce the actual space you can build on, so don't assume the full 1,000 square feet is available on every lot.
Can I rent my ADU on Airbnb?
Only with a separate short-term rental license from the city. The standard ADU permit covers long-term tenancies of 30 days or more. Short-term rentals require an additional approval step.
Does using a pre-approved standard plan speed up permitting?
Yes, noticeably. Standard plans have already cleared design review, so that step is essentially bypassed. If your design preferences are flexible, using one of the city's pre-approved plans is one of the most practical ways to reduce your timeline.
How many ADUs can I have on one lot?
One. Salt Lake City limits each residential lot to a single ADU regardless of lot size.
Do I need separate utility meters for my ADU?
Not always, but separate metering is often required or strongly recommended, particularly for detached units. Confirm utility connection requirements with Salt Lake City Public Utilities and your contractor early in the planning process, since connection costs can be significant.
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