ADU Pass
Clinton
ADU Pass helps homeowners in Clinton, Granite County, Montana navigate the permit paperwork for building an accessory dwelling unit. This area covers 1 ZIP code.
Map
ADU details
ADU legality: allowed
Montana preempts most local ADU restrictions. Clinton permits ADUs by right in single-family zones per its zoning ordinance.
Cost scenarios
| Scenario | Sq ft | Permit | Build | Total |
|---|---|---|---|---|
| minimum | 150 | $2,100 | $39,750 | $41,850 |
| 600 | 600 | $2,100 | $159,000 | $161,100 |
| midpoint | 675 | $2,100 | $178,875 | $180,975 |
| maximum | 1,200 | $2,100 | $318,000 | $320,100 |
Fee breakdown
Viability (permitted uses)
- Long-term rental: yes Long-term rental of ADU explicitly permitted; Montana owner-occupancy preemption (where applicable) makes ADU eligible for full landlord-tenant treatment.
- Short-term rental: with-restrictions STR rules vary by city. Clinton regulates STRs separately from ADU permitting; check local STR ordinance and HOA covenants.
- Office rental: with-restrictions Detached office rental requires home occupation permit or rezoning.
- Home office: yes Home occupation permitted with restrictions on signage and customer traffic.
- Studio / workshop: yes Personal artist studio is a permitted accessory use.
- Agriculture: with-restrictions Limited urban agriculture permitted in residential zones; livestock varies by district.
- Relative support: yes Family-occupancy ADU explicitly permitted in single-family zones.
Utilities
- Water: Clinton Water Utility · 21d connect · $4,500
- Sewer: Clinton Sewer / Wastewater · 21d connect · $5,500
- Electric: Clinton Electric Utility · 14d connect · $1,800
- Gas: Clinton Gas Utility · 21d connect · $1,500
Property values & taxes
Construction timeline
Realistic total: best 7mo · typical 11mo · worst 17mo
Financing
State ADU loans:
Insurance impact
HOA prevalence & preemption
Montana's HOA statute Mont. Code Ann. § 70-17-901 (https://mca.legmt.gov/bills/mca/title_0700/chapter_0170/part_0090/section_0010/0700-0170-0090-0010.html) prohibits an HOA from adopting or enforcing a covenant amendment that imposes more onerous use restrictions than those in place when a member acquired their interest, unless the affected member consents in writing. After 2019-05-09, an HOA also may not enforce a covenant in a way that limits uses that were allowed when the member acquired the property. This is a one-way ratchet protecting existing uses, not an affirmative ADU preemption: an HOA's pre-existing covenant prohibiting ADUs remains enforceable against owners who took title with that restriction in place. SB 528's text expressly addresses municipal zoning, not private covenants, and § 70-17-901(2) carves out covenants required to comply with applicable federal, state, and local laws — but a covenant banning ADUs is not 'required' by SB 528, so the carve-out does not flip pre-existing ADU bans. A homeowner subject to an HOA covenant prohibiting ADUs has no state-law remedy under current Montana law and must seek the consent or amendment process within the association.
Technical envelope (climate & building code)
Climate & energy code
Building code
Amendments:
- Amendment
- Amendment
Legal history (timeline)
Current ordinance: City of Clinton Municipal Code — Accessory Dwelling Units, adopted 2020-01-01, last amended 2024-04-01
- 2024-01-01 — City of Clinton ADU code refresh (city-ordinance)
Conforming local-code amendments aligning with current Montana accessory-dwelling framework.
Effect: Codified by-right ADU standards consistent with state law and local zoning.
Granite County — county ADU rules and overlays
County ADU ordinance
Granite County (Philipsburg county seat; west-central Montana between Missoula and Butte; ~3,400 residents across 1,727 sq mi; mining-historic terrain centered on the Sapphire Mountains, Flint Creek Range, and the eastern Pintler / Anaconda-Pintler Wilderness; gateway to the Anaconda-Pintler Scenic Byway (MT-1); historic silver and sapphire mining heritage with significant operating sapphire mines at Gem Mountain, Rock Creek, and others) does not maintain a comprehensive countywide zoning code, but has adopted citizen-initiated zoning districts under Mont. Code Ann. § 76-2-101 et seq. - notably the Philipsburg-area zoning district and several smaller residential districts. ADUs in those zoning districts are governed by district-specific use tables; outside the districts, ADU construction proceeds through subdivision regulations and Montana state building code (IRC 2018, administered by the Montana Department of Labor & Industry, Building Codes Bureau). Granite County contains two incorporated municipalities: Philipsburg (county seat, ~950 residents) and Drummond (~310). Both are subject to Montana SB 528 (2023, Mont. Code Ann. § 76-2-345) ADU preemption inside their town limits. SB 528 applies to ALL incorporated Montana cities (NOT population-gated per the Montana AG interpretation underlying the MT-CW2 finding). At the COUNTY tier, SB 528 is municipal-only and does NOT reach unincorporated county land. Philipsburg has emerged as one of Montana's most active small-town short-term rental destinations - a restored Victorian-era main street, the Philipsburg Brewing Company, the Sweet Palace candy shop, the Granite County Museum, and proximity to the Discovery Ski Area, Georgetown Lake, and the Anaconda-Pintler Wilderness drive significant tourism demand and STR pressure. Drummond is a smaller agricultural community and rail stop on the I-90 corridor.
State-floor overlay: Montana SB 528 establishes a state ADU floor for incorporated Montana cities; Philipsburg and Drummond are squarely subject inside their town limits. SB 528 does NOT extend to unincorporated Granite County or to the citizen-initiated zoning districts. ADU permissibility on unincorporated parcels is determined by local zoning district where applicable, otherwise by state-level oversight only.
County regulatory overlays
Granite County's overlay landscape includes five material categories: (1) Wildland-Urban Interface - Beaverhead-Deerlodge National Forest, the Anaconda-Pintler Wilderness, and the Sapphire Mountains all generate significant WUI exposure; the Sapphire Mountains, Flint Creek Range, and Pintler gateway parcels carry elevated wildfire risk. (2) FEMA NFIP floodplain along the Clark Fork River (northern county margin), Rock Creek, Flint Creek, and Willow Creek. (3) Anaconda-Pintler Wilderness boundary - the wilderness covers the western and southwestern county margin; USFS has no direct authority over private land but federal-action triggers can apply (Section 7 ESA for bull trout, lynx, grizzly recovery zone). (4) Mining-historic resources - Philipsburg historic district (NRHP), Granite (ghost town NRHP), Hasmark, and other 19th-century silver-mining heritage sites; abandoned mine reclamation remains an ongoing concern under federal SMCRA and Montana DEQ jurisdiction. (5) Sapphire mining areas - Gem Mountain, Rock Creek, and other operating sapphire mines impose mining-claim and federal mineral-rights considerations on adjacent parcels.
- Wildland-Urban Interface - Sapphire Mountains, Flint Creek Range, Anaconda-Pintler gateway, Beaverhead-Deerlodge NF — Voluntary Firewise USA participation is widespread (Philipsburg, Georgetown Lake). Insurance markets are tightening: some carriers have stopped writing new homeowner policies in the highest-WUI zones (Pintler gateway, Discovery Ski Area access, Georgetown Lake). ADU economics need to factor in higher insurance cost (15-30% premium versus equivalent valley-floor parcel).
- FEMA NFIP Special Flood Hazard Areas - Clark Fork River, Rock Creek, Flint Creek, Willow Creek — Spring snowmelt drives late-spring flooding peaks. New ADUs in mapped SFHA must be elevated to or above the Base Flood Elevation; elevation cost can add $20,000-$40,000 in this market. Clark Fork River downstream Superfund implications (residual mining contamination) intersect floodplain compliance in the Bonita / Bearmouth area.
- Anaconda-Pintler Wilderness boundary / USFS Beaverhead-Deerlodge NF — Private inholdings within or adjacent to the wilderness face access constraints. Federally-financed ADU projects (FHA, USDA RD, HUD-184) on adjacent parcels can face Section 7 ESA consultation timelines.
- Philipsburg NRHP Historic District; Granite ghost town NRHP; mining-era heritage sites — ADU work on Philipsburg NRHP-listed contributing properties triggers town historic-preservation review and can add 30-60 days to permit timelines. ADU work on a NRHP-listed contributing property triggers Section 106 review only if federal financing or permitting (FHA, USDA RD, HUD-184) is involved. Philipsburg's restored Victorian streetscape is the town's primary tourism asset; preservation review is taken seriously.
- Mining-claim and abandoned-mine overlay — Title research on Granite County rural parcels should include mineral-rights review. ADU construction on or adjacent to abandoned mine sites can encounter waste-rock contamination requiring Montana DEQ remediation review. The Clark Fork River Superfund Operable Unit (downstream of Butte) has tail-end impacts in the Bonita / Bearmouth area of northern Granite County.
County permitting (unincorporated parcels)
Granite County issues no countywide building permits for residential construction in unincorporated areas; like most rural Montana counties without a full county building department, building-code enforcement is delegated to the State of Montana (Department of Labor & Industry, Building Codes Bureau) only for certain commercial or state-jurisdiction projects. Single-family residences and ADUs in unincorporated Granite County are typically constructed without municipal-style plan review. State-level oversight applies to on-site septic (DEQ Subdivision review for parcels created after 1973) and well construction (DNRC water rights). Floodplain development requires a permit through the county floodplain administrator under MCA Title 76 Ch. 5 - applicable along the Clark Fork River, Rock Creek, Flint Creek, and other corridors. Citizen-initiated zoning districts (Philipsburg-area and others) impose additional zoning verification through the Granite County Planning Office. Philipsburg and Drummond operate their own town permitting processes inside town limits. Granite County is in IECC climate zone 6B-7; high-elevation parcels in the Pintler / Anaconda-Pintler gateway face elevated snow loads (60-90 psf typical at valley floors, 90-120+ psf at higher elevations approaching the wilderness boundary).
Montana state — ADU law and programs
State ADU law
Montana has enacted strong statewide ADU preemption through Senate Bill 528 (2023), codified at Mont. Code Ann. § 76-2-345. SB 528 is part of the 2023 'Montana Miracle' housing reform package (also including SB 323 duplex preemption and SB 245 commercial-zone multifamily). SB 528 requires every Montana city to allow at least one ADU by right on any lot containing a single-family dwelling, with size capped at the lesser of 1,000 sq ft or the floor area of the primary dwelling. ADUs may be attached, detached, or internal. Cities are prohibited from requiring additional parking, fees, design-match to the primary dwelling, owner-occupancy, occupant-relationship limits, or impact fees specifically for ADUs. ADUs must still meet building, fire, and public-health codes. Effective 2024-01-01. The Montana Supreme Court (September 2024) lifted a Gallatin County district-court injunction obtained by Montanans Against Irresponsible Densification (MAID), allowing the law to take effect; a Daily Montanan March 2025 ruling confirmed the affordable-housing bills are a 'legitimate government concern.' The 2025 session continued the reform trajectory (HB 533 wildfire-insurance transparency); no rollback bills have advanced as of 2026-04-26.
State HOA preemption
Montana's HOA statute Mont. Code Ann. § 70-17-901 (https://mca.legmt.gov/bills/mca/title_0700/chapter_0170/part_0090/section_0010/0700-0170-0090-0010.html) prohibits an HOA from adopting or enforcing a covenant amendment that imposes more onerous use restrictions than those in place when a member acquired their interest, unless the affected member consents in writing. After 2019-05-09, an HOA also may not enforce a covenant in a way that limits uses that were allowed when the member acquired the property. This is a one-way ratchet protecting existing uses, not an affirmative ADU preemption: an HOA's pre-existing covenant prohibiting ADUs remains enforceable against owners who took title with that restriction in place. SB 528's text expressly addresses municipal zoning, not private covenants, and § 70-17-901(2) carves out covenants required to comply with applicable federal, state, and local laws — but a covenant banning ADUs is not 'required' by SB 528, so the carve-out does not flip pre-existing ADU bans. A homeowner subject to an HOA covenant prohibiting ADUs has no state-law remedy under current Montana law and must seek the consent or amendment process within the association.
State financing programs
Montana Board of Housing (MBOH) under the Montana Department of Commerce does not operate an ADU-specific loan or grant product as of 2026-04-26. Construction or rehab of an ADU on a primary residence may be financed indirectly through MBOH's Regular Bond Loan Program (30-year, low-interest first mortgage geared to first-time buyers under income and purchase-price limits) or the Bond Advantage / MBOH Plus Down Payment Assistance Programs (up to 5% / $15,000 in DPA). All MBOH first-mortgage products require qualifying for an underlying FHA, VA, RD, or HUD-184 loan; an existing ADU on the property is generally permissible. The Department of Commerce's Coal Trust Multifamily Loan Program funds rental housing developments which can include ADU-style units in multi-unit projects but is not a homeowner-facing instrument.
State housing programs
Montana does not operate a statewide pre-approved ADU plan catalog as of 2026-04-26. The 2023 Montana Miracle reform package (SB 528, SB 323, SB 245, SB 382) established the country's most aggressive state preemption of single-family-only zoning, but did not pair the preemption with a state plan library, impact-fee waiver fund, or per-ADU rebate. SB 382 (the Montana Land Use Planning Act, https://archive.legmt.gov/bills/2023/BillPdf/SB0382.pdf) restructures comprehensive-planning requirements for cities of 5,000+ residents toward a more streamlined, plan-then-permit model. Implementation by the Department of Commerce and the Department of Environmental Quality continues; the DEQ Energy Code office published an ADU best-practices guide in fall 2023.
Federal (United States) — ADU-relevant rules and programs
Federal ADU law
The United States has no federal statute that directly regulates accessory dwelling unit entitlement or design. Land-use authority over ADUs resides with states and local governments under the traditional police power. Federal engagement is limited to financing (Fannie/Freddie/FHA/VA/USDA), flood insurance (FEMA/NFIP), and discretionary housing programs (HUD), which are recorded in sibling sections of this file.
Federal financing programs
Federal housing-finance agencies and GSEs set nationwide underwriting rules that govern whether an ADU can be financed, appraised, and counted toward mortgage qualifying income. The relevant actors are Fannie Mae, Freddie Mac, FHA (HUD), VA, and USDA Rural Development.
Federal tax credits
There is no ADU-specific federal tax credit. ADUs may incidentally qualify for existing federal energy-efficiency and clean-energy tax credits when the ADU construction includes qualifying measures.
Federal housing programs
HUD administers several discretionary programs that can fund ADU-related activity at the grantee's election, but none is an ADU-specific program.
ZIP Code
- 59825
Post Office
- 20455 E Mullan Rd, 59825