An ADU builder in Salt Lake City is a licensed contractor who designs and constructs accessory dwelling units — detached backyard units, garage conversions, attached additions, and junior ADUs (JADUs). Because an ADU is a complete second dwelling, the builder coordinates foundation, framing, plumbing, electrical, and HVAC work and pulls it through Salt Lake City's permit process and utility connections. Not every general contractor has built one, so the right builder is one with ADU-specific experience in Utah.
What ADU Builders Cost in Salt Lake City [10][11]
Based on our Salt Lake City cost data, expect the following ranges from local ADU builders. Quotes for the same scope typically vary 20-40% between contractors, so getting at least three bids is the single best way to control cost.
| New Detached ADU (all-in) | $180,000-$350,000 |
| Cost per Sq Ft | $300-$350 |
| Garage Conversion | $120,000-$200,000 |
| Prefab / Modular ADU (installed) | $100,000-$180,000 |
| City Permit & Plan Review | About $3,000-$5,000 in building-permit plus plan-review fees for a $150,000-$300,000 ADU: permit $1,425.97 plus $8 per $1,000 over $100,000 (Code 18.32.035), plan review 65% of that (FY2027 Consolidated Fee Schedule, amended 6/16/2026). Trade permits and a $35-per-unit rental licence are extra. |
| Impact Fees | Charged on every new dwelling unit (ADU Handbook v2.2). FY2027 city impact fees per residential unit: single-family rate $5,832 (park $5,173, transportation $429, fire $171, police $59) or multi-family rate $3,550 (park $3,078, transportation $242, fire $171, police $59); Building Services (801-535-7712) assigns the ADU's category. A $545 sewer and $1,871 water connection fee apply only if the ADU gets its own service; storm water $374 per 1/4 acre where it applies (CFS FY2027; Code 18.98, 17.44.060, 17.16.040). |
For a full line-item breakdown, see our Salt Lake City ADU cost guide. To confirm what you're allowed to build before you hire, review the Salt Lake City ADU rules (max detached size: 1,000 sq ft of gross floor area (21A.40.200.J.1). Only the ADU's floor area counts when the building also holds a garage or other accessory use; stairs to a second-level ADU, loft space under 7 ft and a storage-only basement with no internal connection are excluded (J.3). A covered patio up to 120 sq ft does not count toward the cap but does count toward lot coverage (H.3). Accessory buildings together may cover at most 50% of the rear yard in single/two-family districts (ADU Handbook v2.2).; owner-occupancy: Required on single-family lots: a deed-listed owner, a relative by blood, marriage or adoption, or a family-trust trustor must live in the house or the ADU (21A.40.200.C). Not required when the principal use is a duplex, multi-family or non-residential building (C.4.a); absences of up to 3 years for military service or job assignments and moves into medical or nursing care are excused (C.4.b-c). A recorded restrictive covenant carries the requirement and bans short-term rental of both units (P).).
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How to Vet an ADU Builder in Salt Lake City
- License: Confirm a current contractor's license in Utah and that it's in good standing. Ask for the license number and verify it with the state board.
- ADU-specific experience: Ask how many ADUs they've completed in or near Salt Lake City and request addresses or photos. ADU permitting and setbacks differ from a kitchen remodel.
- Portfolio & references: Get references from recent ADU clients and, if possible, visit a finished unit.
- Insurance: Verify general liability and workers' compensation coverage. Ask for a certificate of insurance.
- Written, detailed bid: Insist on an itemized, fixed-price or clearly-scoped bid — not a verbal estimate. It should state whether permits (About $3,000-$5,000 in building-permit plus plan-review fees for a $150,000-$300,000 ADU: permit $1,425.97 plus $8 per $1,000 over $100,000 (Code 18.32.035), plan review 65% of that (FY2027 Consolidated Fee Schedule, amended 6/16/2026). Trade permits and a $35-per-unit rental licence are extra.), plan check (65% of the building-permit fee (Code 18.32.035, CFS FY2027). Expedited review costs twice the standard plan-review fee (18.20.050); review of an identical plan set is 30% (Utah HB 368, 2025). Review duration is not published.), and impact fees (Charged on every new dwelling unit (ADU Handbook v2.2). FY2027 city impact fees per residential unit: single-family rate $5,832 (park $5,173, transportation $429, fire $171, police $59) or multi-family rate $3,550 (park $3,078, transportation $242, fire $171, police $59); Building Services (801-535-7712) assigns the ADU's category. A $545 sewer and $1,871 water connection fee apply only if the ADU gets its own service; storm water $374 per 1/4 acre where it applies (CFS FY2027; Code 18.98, 17.44.060, 17.16.040).) are included.
- Permit handling: Confirm they manage Salt Lake City's permit process ("Building permit through Building Services for every ADU (21A.40.200.M); plans are also reviewed by Public Utilities, Engineering and Transportation (ADU Handbook v2.2, p. 26). Before occupancy: record the ADU restrictive covenant with the Salt Lake County Recorder and give Planning a copy (P.6), obtain a zoning certificate (O.1) and, if renting, a rental dwelling business licence with Good Landlord enrolment (O.2). A licensed general contractor must pull the permit for an attached second unit (Utah Code 58-55-301, 58-55-305).", typically Review times are not published. The Handbook shows building-code, fire, Public Utilities, Engineering and Transportation reviews before the permit, then covenant, owner-occupancy and zoning-certificate steps before occupancy; ask Building Services (801-535-7968) for the current residential queue.) and who is responsible if revisions are required.
- Payment schedule: Avoid large upfront payments. A reasonable schedule ties payments to completed milestones.
Questions to Ask Before You Hire
- How many ADUs have you built in Salt Lake City in the last two years?
- Is your bid fixed-price, and what would trigger a change order?
- Are permits, plan check, and utility connection fees included?
- What's a realistic timeline, including permit review (Review times are not published. The Handbook shows building-code, fire, Public Utilities, Engineering and Transportation reviews before the permit, then covenant, owner-occupancy and zoning-certificate steps before occupancy; ask Building Services (801-535-7968) for the current residential queue.) and construction?
- Who is my point of contact and how are delays communicated?
- What warranty do you provide on workmanship?
- Can you share three recent Utah ADU client references?
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