Accessory Dwelling Unit (ADU) Permit in Kalispell, Montana

Kalispell requires an accessory dwelling unit (adu) permit for: An ADU (or a second unit provided as part of a duplex) is a permitted use in any zone where a single-family dwelling is a permitted use (KMC 27.20.082(1), as amended by Ord. 1950, eff. 5-4-2026); Maximum height: single story, no more than 18 feet, unless the setbacks for a principal structure are met (in which case the district's standard maximum building height applies) — KMC 27.20.082(2)(a); Gross floor area of living space limited to no more than 1,000 square feet — KMC 27.20.082(2)(b); Rental periods of less than 30 days are not permitted for an ADU (i.e., ADUs cannot be used as short-term rentals) — KMC 27.20.082(2)(c); An ADU shall not contain more than one dwelling unit — KMC 27.20.082(2)(d); An ADU must meet the setbacks required for a principal structure, unless an existing conforming or nonconforming accessory structure is being converted into the ADU (in which case existing setbacks may be maintained) — KMC 27.20.082(3)(a); A building permit is required for all ADU construction, reviewed against the 2021 IRC and applicable zoning standards; Separate trade permits (electrical, plumbing, mechanical) required for ADU construction. If your project isn't listed, confirm with City of Kalispell Building Department at (406) 758-7730 before starting work.

In Kalispell, the published Building Permit Fee — valuation-based (same Building Permit Fee Schedule as new construction) is: $23.50 minimum (valuation $1-$500) scaling to $6,444.85 for the first $1,000,000 plus $5.25 per additional $1,000 over $1,000,000. These are the jurisdiction's own published figures — see the fee schedule table and source citations on this page.

Kalispell's published plan-review target for an accessory dwelling unit (adu) permit is 14–21 business days.

You'll need: Residential Building Permit Application; Site Plan. See the required-documents checklist on this page for details on each.

Kalispell requires 4 inspection(s) for an accessory dwelling unit (adu) permit, in order: Foundation, Framing, MEP Rough-In, Final. Schedule each through City of Kalispell Building Department ((406) 758-7730).

Apply through City of Kalispell Building Department at 201 1st Avenue East, Kalispell, MT 59901 (mailing: PO Box 1997, Kalispell, MT 59903). Phone: (406) 758-7730, email: bldgdept@kalispell.com. Office hours: Not published on the department page; phone (406) 758-7730 and email bldgdept@kalispell.com listed as primary contact methods. Official information: https://www.kalispell.com/614/Building.

Kalispell, Montana has adopted: 2021 International Building Code (IBC) — with Montana/Kalispell amendments; 2021 International Mechanical Code (IMC); 2021 International Fuel Gas Code (IFGC); 2021 International Fire Code (IFC); 2021 International Existing Building Code (IEBC); 2021 International Residential Code (IRC); 2021 Uniform Plumbing Code (UPC) — Montana uses the Uniform Plumbing Code, not the International Plumbing Code; 2021 Energy Code; 2020 National Electrical Code (NEC) / NFPA 70; 2021 International Swimming Pool and Spa Code (ISPSC). Local amendments apply — see the Kalispell overview page for the full list.

As of Ordinance 1950 (effective May 4, 2026), an ADU is a permitted use in any zone where a single-family dwelling is a permitted use in Kalispell. It is limited to 1,000 square feet of living space, a single story/18-foot height (unless full principal-structure setbacks are met), and cannot be used as a short-term rental (minimum 30-day rental period). Source: Kalispell Municipal Code Section 27.20.082.