Do ADUs require owner-occupancy or extra parking in Missoula?

No. Ordinance 3669, adopted by the Missoula City Council on October 19, 2020, removed both the owner-occupancy requirement and the additional off-street parking requirement for ADUs, though any parking required for the primary dwelling must still be maintained.

How big can an ADU be in Missoula?

Detached ADUs are capped at 600 sq ft. Internal ADUs are capped at the lesser of 40% of the primary dwelling's gross floor area (excluding an attached garage) or 600 sq ft. Maximum detached ADU height is 25 feet. Source: Missoula Municipal Code 20.45.060, as amended by Ordinance 3669.

Accessory Dwelling Unit (ADU) Permit in Missoula, Montana

Verified

Required for construction of a new accessory dwelling unit (detached, internal, or internal addition) on a residential parcel within Missoula city limits. Governed by Missoula Municipal Code Title 20 (Zoning), Section 20.45.060, as amended by Ordinance 3669 (October 2020), which removed the prior owner-occupancy and additional-parking requirements. A building permit is required in addition to zoning compliance review.

Verified 2026-07-02 · Source

$36Building Permit Fee — valuation-based (same table as new residential construction)

When you need this permit

ADUs allowed by right in all Residential, Business (B), Commercial (C), and Limited Industrial-Residential (M1-R) zoning districts
One ADU permitted per parcel occupied by a single detached house; not allowed in special districts or PUDs unless the district/PUD expressly permits them
Detached ADU floor area capped at 600 sq ft (per MMC 20.45.060.B.8.a, as amended by Ordinance 3669)
Internal ADU floor area capped at the lesser of 40% of the primary dwelling's gross floor area (excluding attached garage) or 600 sq ft
Maximum detached ADU height: 25 feet (MMC 20.45.060.C.3, as amended by Ordinance 3669)
No owner-occupancy requirement (removed by Ordinance 3669, effective ~November 2020)
No additional off-street parking required for the ADU itself, though existing required parking for the primary dwelling must be maintained
Building permit required for all new ADU construction or conversion of existing structures to include an ADU — apply through Accela Citizen Access

Required documents

Required
Building Permit Application (Accela Citizen Access)
Submitted online for the ADU construction or conversion scope
Required
Construction Drawings
Site plan, floor plan, elevations demonstrating compliance with size and height limits under MMC 20.45.060

Fee schedule

Fee type	Amount	Notes
Building Permit Fee — valuation-based (same table as new residential construction)	$36 minimum (valuation $1–$500) up to $1,582 for the first $100,000 plus $9.94 per additional $1,000; see full valuation table	City of Missoula FY26 Building Permit and Plan Review Fee Schedule (Resolution 8887, effective Jan 1–Dec 31, 2026)

Review timeline

~56–84 business days

Typical estimate — confirm current times with the Missoula building department

Inspection process

1
Footing and Foundation
Before concrete pour (detached ADU)
2
Framing/Structural
Structural framing, egress, fire separation
3
MEP Rough-In
Mechanical, electrical, plumbing rough-ins before wall cover
4
Final
All work complete, ready for occupancy

Tips

As of Ordinance 3669 (October 2020), Missoula ADUs no longer require owner-occupancy or a deed restriction, and no longer require an additional off-street parking space — verify current status with Development Services since ADU policy has been an active area of city housing-policy revision.
Detached and internal ADUs are capped at 600 sq ft; internal ADUs also cannot exceed 40% of the primary dwelling's gross floor area.
Confirm zoning eligibility before applying — ADUs are not allowed in special districts or PUDs unless the district/PUD explicitly permits them.
Contact Development Services' zoning information line at (406) 552-6625 or the general Building Division line at (406) 552-6630 to confirm current ADU rules for your parcel.

Frequently asked questions

Do ADUs require owner-occupancy or extra parking in Missoula?: No. Ordinance 3669, adopted by the Missoula City Council on October 19, 2020, removed both the owner-occupancy requirement and the additional off-street parking requirement for ADUs, though any parking required for the primary dwelling must still be maintained.
How big can an ADU be in Missoula?: Detached ADUs are capped at 600 sq ft. Internal ADUs are capped at the lesser of 40% of the primary dwelling's gross floor area (excluding an attached garage) or 600 sq ft. Maximum detached ADU height is 25 feet. Source: Missoula Municipal Code 20.45.060, as amended by Ordinance 3669.

Sources & verification

Verified against official sources. Last reviewed 2026-07-02.

Fees, timelines, and adopted codes are researched from each jurisdiction's published records — see how we verify. Requirements change and vary by project, so always confirm the current details with the Missoula building department before you submit. PermitBase is an independent reference and is not affiliated with any government agency.

Other permits in Missoula

Residential Building Permit (New Construction)Residential Addition / Remodel / Alteration Permit Residential Electrical Permit Residential Plumbing Permit Residential Mechanical / HVAC Permit Residential Re-Roof Permit Solar Photovoltaic (PV) Permit

Accessory Dwelling Unit (ADU) Permit in other cities

Bozeman, Montana Great Falls, Montana Helena, Montana Kalispell, Montana Unincorporated Yellowstone County, Montana Albuquerque, New Mexico Arvada, Colorado Aurora, Colorado

Compare accessory dwelling unit (adu) permit fees across Montana →

Related guides

ADU / In-Law Suite

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