Accessory Dwelling Unit (ADU) in Washington City, Utah

Washington City requires an accessory dwelling unit (adu) permit for: Property must qualify under Washington City Ordinance #2019-25 — contact Planning and Zoning at (435) 656-6325 before creating plans; Accessory Dwelling Unit Deed Restriction — must be completed, notarized, and recorded at the Washington County Assessor's office; the recorded document is uploaded with the permit application; Site plan showing lot layout, setbacks, easements, topographical details (if slope >10%), utilities, and nearest hydrant location; Defensible space provisions per the Utah Wildland Urban Interface Code (adopted under Utah Code § 15A-2-103), if required. If your project isn't listed, confirm with Washington City Building Department at (435) 656-6326 before starting work.

In Washington City, the published Building Permit is: Valuation-based per the Washington City Building Permit Fee Table (see residential building permit fees above). These are the jurisdiction's own published figures — see the fee schedule table and source citations on this page.

Washington City does not publish a plan-review timeline for this permit. Contact Washington City Building Department at (435) 656-6326 for current turnaround.

You'll need: Online Permit Application (CityInspect Builder Account); ADU Deed Restriction; Site Plan. Depending on your project, Washington City may also ask for: Owner Builder Certification. See the required-documents checklist on this page for details on each.

Washington City requires 3 inspection(s) for an accessory dwelling unit (adu) permit, in order: Foundation, Framing, Final. Schedule each through Washington City Building Department ((435) 656-6326).

Apply through Washington City Building Department at 111 N 100 E, Washington, UT 84780. Phone: (435) 656-6326. Office hours: Mon–Thu 7:30am–5:30pm, Fri 8am–Noon. Official information: https://washingtonutah.gov/development/building.

Washington City, Utah has adopted: 2024 International Building Code (IBC), including Appendices C and J — CURRENT statewide as of 7/1/2026 per Utah Code § 15A-2-103(1)(a). Washington City Building Department's own 'Climatic and Geographic Design Criteria' notice was live-checked 2026-07-16 (raw HTML, not an AI summary) and STILL displays '2021 IBC' — the city page has NOT been updated to reflect the statewide 7/1/2026 transition; 2021 Utah State Residential Code (based on IRC) — REMAINS CURRENT; Utah Code § 15A-2-103(1)(b) did not change this edition in the 7/1/2026 amendment. Washington City's own page (live-checked 2026-07-16) correctly still shows '2021 UTAH STATE RESIDENTIAL CODE'; Appendix AQ of the 2021 IRC — statewide per Utah Code § 15A-2-103(1)(c); not separately itemized on Washington City's own page, added here per statute; 2024 International Plumbing Code (IPC) — CURRENT statewide as of 7/1/2026 per Utah Code § 15A-2-103(1)(d). Washington City's own page was live-checked 2026-07-16 and STILL displays '2021 IPC' — the city page has NOT been updated; 2024 International Mechanical Code (IMC) — CURRENT statewide as of 7/1/2026 per Utah Code § 15A-2-103(1)(e). Washington City's own page was live-checked 2026-07-16 and STILL displays '2021 IMC' — the city page has NOT been updated; 2024 International Fuel Gas Code (IFGC, listed on city page as 'IFCI') — CURRENT statewide as of 7/1/2026 per Utah Code § 15A-2-103(1)(f). Washington City's own page was live-checked 2026-07-16 and STILL displays '2021 IFCI' — the city page has NOT been updated; 2023 National Electrical Code (NEC) — REMAINS CURRENT; Utah Code § 15A-2-103(1)(g) did not change this edition in the 7/1/2026 amendment. Washington City Building Department page explicitly updated 'MAY 7 2025 UPDATE OF ADOPTED CODES BY THE STATE OF UTAH: 2023 NEC code update' (superseding the previously listed 2020 NEC, still shown struck-through/superseded on the live page as of 2026-07-16); this is one of the few Washington County-area jurisdiction pages independently confirmed current on the electrical code edition, not just inferred from state law; 2024 International Energy Conservation Code (IECC), single unsplit statewide edition — CURRENT statewide as of 7/1/2026 per Utah Code § 15A-2-103(1)(h). Washington City's own page was live-checked 2026-07-16 and STILL displays '2021 IECC' — the city page has NOT been updated; Residential provisions of the 2024 International Swimming Pool and Spa Code (ISPSC) — CURRENT statewide as of 7/1/2026 per Utah Code § 15A-2-103(1)(n). Washington City's own page was live-checked 2026-07-16 and STILL displays '2021 ISPSC', and the city's Swimming Pool permit instructions (ISPSC sections 305.3.3/305.3.4, 807, 809, 323) likewise still cite the 2021 edition — the city has NOT updated either page; 2024 International Existing Building Code (IEBC) — statewide per Utah Code § 15A-2-103(1)(i); NOT listed at all on Washington City's own Building Department page (live-checked 2026-07-16), added here per statute since the City's own materials omit it entirely; ICC A117.1-2009 or 2017 (Accessibility Standard) — listed on Washington City Building Department page; not part of Utah Code § 15A-2-103's construction-code list, left unchanged; 2018 IBC construction-type valuation table (ICC Building Valuation Data) — used directly in the city's own published 'Square Foot Construction Costs Table B' on its fee schedule; a fee-calculation reference table, not a code edition, left unchanged; NOTE (2026-07-16 re-verification): The Utah Code § 15A-2-103 version effective 7/1/2026 (superseded 1/1/2027) took effect 15 days before this re-verification. IBC/IPC/IMC/IFGC/IECC/IEBC/residential ISPSC are now 2024 statewide; IRC (2021) and NEC (2023) did NOT change. Washington City's own Building Department page ('Climatic and Geographic Design Criteria' notice) was independently re-fetched 2026-07-16 (raw HTML, not an AI summary, to guard against summarizer fabrication) and STILL displays 2021 editions for IBC/IMC/IPC/IFCI(IFGC)/IECC/ISPSC — confirmed NOT updated to reflect the statutory transition, unlike its NEC line which was separately updated in May 2025. This file now states the governing statutory codes (2024/2021/2023 editions per subsection) as current per Utah's statewide-mandatory code regime (Utah Code § 15A-1-204), while preserving the City's own (lagging) page text above as historical/local-document context. The Utah Code § 15A-2-103 citation in the sources array below has been updated to the current in-force version link. Local amendments apply — see the Washington City overview page for the full list.

Only if your property qualifies under City Ordinance #2019-25. Washington City's Building Department instructs applicants to contact Planning and Zoning at (435) 656-6325 to confirm eligibility before creating any plans. A recorded Deed Restriction is also required.