Accessory Structures in Billings, MT (2026)
3 verified accessory structures rules for Billings, Montana, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
Billings allows one accessory dwelling unit on any lot where a single dwelling is permitted or already exists, as long as the lot holds at least 3,000 square feet. The ADU is capped at 80 percent of the main home's floor area or 1,000 square feet, whichever is less, and it can never be sold separately from the primary dwelling or lot.
Billings, MT Accessory Dwelling Unit (ADU) Rules
Some RestrictionsBillings City Code § 27-1008(G)
G. Accessory dwelling units. 1. Applicability. (a) Accessory dwelling units are permitted on any parcel where a single dwelling unit is permitted or currently exists. (b) The minimum lot size for a lot that has both a primary dwelling unit and an accessory dwelling unit is three thousand (3,000) square feet. 2. Ownership and occupancy. (a) The accessory dwelling unit shall not be sold separatel...
ADU Owner Occupancy
Billings requires the property owner to live in either the main house or the ADU at least six months a year, with a recorded deed restriction.
Billings ADU Owner-Occupancy Rule
Some RestrictionsSec. 27-1008(G)(2), Billings Municipal Code
2.Ownership and occupancy.(a)The property owner shall live in either the primary or accessory dwelling unit, with one of the units serving as their principal residency for at least six months in a year. No third-party rentals shall occur in the owner-occupied unit.(b)The property owner shall record a deed restriction with the Yellowstone County Recorder requiring owner-occupancy of the property.
Shed & Carport Rules
Billings zoning caps detached accessory buildings like sheds and shops at 1,500 square feet once they pass 200 square feet, and bars building in a required setback or within 5 feet of another structure.
Billings Shed and Accessory Building Size Rules
Some RestrictionsSec. 27-1008
No accessory building shall be erected in any required setback nor within five (5) feet of any other building except as specified in this section. ... Detached buildings for accessory residential uses ... greater than two hundred (200) square feet in size shall not exceed the principal building first story gross floor area on the lot or one thousand five hundred (1,500) square feet, whichever i...
Looking for Yellowstone County county-wide rules?
County ordinances apply to unincorporated areas and may supplement Billings city rules.
Accessory Structures in Yellowstone County →