Irontown Modular · Authorized Dealer

Modular ADU homes in Montana

My Cozy Outdoors is your authorized Irontown Modular dealer and direct point of contact through move-in. Irontown, the seller of record, brings more than 40 years of building experience to your backyard home.

Designed to the International Residential Code; set on a permanent foundation
Delivery and crane set included for the first 250 miles, then per truckload
Free zoning guidance with your quote
10 year limited structural warranty

Get a Quote and Zoning Guidance See the City and County Rules

What counts as a Montana ADU?

Montana defines an accessory dwelling unit as a self-contained living unit on the same parcel as a larger single-family dwelling, with its own cooking, sleeping and sanitation facilities. Mother-in-law suite, guest house, backyard cottage, casita, granny flat, tiny home and prefab ADU are everyday names for the same thing.

A modular ADU is factory-built to the International Residential Code, with engineered stamped plan sets, then set by crane on a permanent foundation as real property. A park model on wheels or any tiny home on wheels is a different product outside this guide.

Where can you put a modular ADU?

Start with zoning, permits, fees, covenants and code compliance. Before ordering, confirm zoning, permits, fees and covenants with local planning, and septic and well capacity with your county sanitarian. MCO shares code sections and suggested questions.

Start With Local Guidance
This guide is a starting point. MCO helps and advises but takes no responsibility for zoning, permits, impact fees, septic approval or code compliance. Before ordering, you must confirm your parcel, model and use with city or county planning and building offices, and septic approval with the health department. We strongly recommend contacting those offices. MCO can share the code sections it found and suggest questions.

Montana’s city and county ADU laws

MCA 76-2-345 binds every municipality since January 1, 2024; Montana’s Supreme Court upheld it March 17, 2026. Section 76-2-215 binds county land zoned under the county zoning part since October 1, 2025. Unzoned county land has no zoning rule.

Every city and town must allow at least one ADU by right on a single-family dwelling lot. Its ADU application fee cannot exceed $250.
The municipal cap is 1,000 sq ft or 75 percent of the house’s gross floor area, whichever is less. A city may allow more.
Municipalities cannot require owner occupancy, family relationships, parking, design matching, impact fees or restrictive covenants. Water and sewer will-serve letters remain possible; short-term rental rules stay local.
Counties that zone under the county zoning part must allow one ADU by right. DEQ provides 15-day expedited sanitation review where existing public water and wastewater service has capacity.
Building, fire, health codes and private covenants remain. Unzoned land retains septic permits, applicable state sanitation review, state electrical and plumbing permits, and floodplain rules.
The Department of Labor and Industry reviews model plans and a state-approved agency inspects factory work; approved units need only local zoning, utility and foundation checks.

Montana city and town rules

Every listed city and town is bound by state ADU law since January 1, 2024. Rows show September 2026 published codes, including unconformed rules. Where a local rule conflicts, ask the city how it applies state law now.

City	Detached ADU	What the local rule says
Bozeman	Allowed with conditions	Capped at 1,000 sq ft or 75 percent of the house, whichever is larger, under 38.320.120.B. Detached units need neighborhood compatibility; ask the city. Phone 406-582-2260.
Belgrade	Allowed with conditions	R and RS cap detached units at 1,000 sq ft; 10-3-39 still prints owner occupancy. Ask which rules apply and how the office measures floor area. Phone 406-388-3760.
Manhattan	Allowed with conditions	Capped at 1,000 sq ft or 75 percent of the house, whichever is less, under 10-19. Water and sewer will-serve letters required; short-term rentals prohibited. Phone 406-284-3235.
Three Forks	Ask first	Capped at 1,000 sq ft or 75 percent of the house, whichever is less. Ask whether 11-6A-5‘s 900 sq ft minimum applies. Phone 406-285-3431.
West Yellowstone	Allowed with conditions	Capped at 1,000 sq ft or 75 percent of the house, whichever is less, under 17.30. Water and sewer will-serve letters required; residential short-term rentals prohibited. Phone 406-646-7795.
Livingston	Allowed with conditions	Under 30.43, capped at 1,000 sq ft or 75 percent of the house, whichever is less. Ask how the office measures floor area. Phone 406-222-0083.
Big Timber	Ask first	State law caps ADUs at 1,000 sq ft or 75 percent of the house, whichever is less. Ask about 700 sq ft minimums and 154.242‘s one-story limit. Phone 406-932-5470.
Red Lodge	Allowed with conditions	Capped at 1,200 sq ft under 4.4.22(F). Short-term rentals need a licence; a rewrite is drafted, so ask which rules apply. Phone 406-446-1606.
Butte-Silver Bow	Ask first	State law caps ADUs at 1,000 sq ft or 75 percent of the house, whichever is less. Ask whether 17.10.040‘s one-story rule excludes the two-story Rabbit 1000. Phone 406-497-6250.
Anaconda-Deer Lodge	Allowed with conditions	Capped at 1,000 sq ft or 75 percent of the house, whichever is less. Septic and well need sanitarian approval; ask about 24-73‘s hearing requirement. Phone 406-563-4010.
Helena	Allowed	Capped at 1,000 sq ft or 75 percent of the house, whichever is less, under 11-2-5 J. City water and sewer required; ask about the rewrite. Phone 406-447-8490.
East Helena	Ask first	State cap: 1,000 sq ft or 75 percent of the house, whichever is less. Ask how state law replaces 6.1.04‘s accessory-dwelling prohibition. Phone 406-227-5321.
Dillon	Ask first	State cap: 1,000 sq ft or 75 percent of the house, whichever is less. Will-serve letter required; ask about 17.60.110 and 17.12.030 E’s story limit. Phone 406-683-4245.
Ennis	Ask first	State cap: 1,000 sq ft or 75 percent of the house, whichever is less. Ask whether the 1,000 sq ft manufactured-housing minimum applies to modular ADUs. Phone 406-682-4287. Source: Ennis Town Code Title 11 (zoning regulations), Sec. 11-4-3 (structure and site development provisions), current through Ordinance 159-2024
Deer Lodge	Ask first	State cap: 1,000 sq ft or 75 percent of the house, whichever is less. Ask about 550 and 700 sq ft minimums and 11.01.150.090‘s width rule. Phone 406-846-2238.
Missoula	Allowed	No size cap under 1.1.04-F.3: residential parcels allow two dwellings by right. No owner occupancy; short-term rentals need registration under 4.8.05-O. Ask the city about current fees. Phone 406-552-6625.
Hamilton	Allowed with conditions	Capped at 1,000 sq ft or 75 percent of the house, whichever is less, under 17.16.010.A.5. District lot minimums apply; ask the city. Phone 406-363-2101 ext. 218.
Stevensville	Ask first	Does 10-230‘s 1,000 sq ft dwelling minimum apply? Whether the town adopted state law could not be read. Phone 406-777-5271.
Kalispell	Allowed with conditions	Capped at 1,000 sq ft under 27.20.082; ask how the office measures floor area. An 18 ft one-story rule applies unless principal setbacks are met. Phone 406-758-7940.
Whitefish	Allowed with conditions	Capped at 1,000 sq ft or 75 percent of the house, whichever is less, under 11-3-1.B. Short-term rentals restricted; ask about pending codification. Phone 406-863-2410.
Columbia Falls	Allowed with conditions	Capped at 800 sq ft by administrative permit under 18.411.010; larger units need conditional approval. Rentals must last a month; ask which rewrite applies. Phone 406-892-4432.
Polson	Allowed with conditions	Ground floor capped at 50 percent of the house’s ground floor under 6.04.430.3. Renting requires owner occupancy and deed restriction; ask whether state limits apply. Phone 406-883-8213.
Libby	Allowed with conditions	Capped at 1,000 sq ft or 75 percent of the house, whichever is less. Ask about 14.02.060‘s width, city-utility requirements and 17.12.070’s 15 ft height. Phone 406-293-2731.
Billings	Allowed with conditions	Capped at 1,000 sq ft or 80 percent of the house, whichever is less, under 27-1008.G.4. Ask whether detached units instead use 75 percent. Phone 406-247-8676.
Laurel	Ask first	State cap: 1,000 sq ft or 75 percent of the house, whichever is less. Current zoning unread; ask which text replaces 17.08.030‘s rental prohibition. Phone 406-628-4796.
Great Falls	Allowed with conditions	Capped at 1,000 sq ft or 75 percent of the house, whichever is less. Ask about Exhibit 20-9‘s height limits and water and sewer letters. Phone 406-455-8430.
Havre	Ask first	State cap: 1,000 sq ft or 75 percent of the house, whichever is less. Ask whether Title 11‘s Class A 1,500 sq ft minimum applies. Phone 406-265-6719.
Miles City	Allowed with conditions	Ground floor capped at 50 percent of the house’s ground floor under 24-65(c)(5). Ask which cap applies and whether DEQ approval is required. Phone 406-234-3493.
Lewistown	Ask first	State law caps ADUs at 1,000 sq ft or 75 percent of the house, whichever is less. Ask about 11-4-1(A); R-1A’s story limit excludes the two-story Rabbit 1000. Phone 406-535-1775.
Glendive	Ask first	State cap: 1,000 sq ft or 75 percent of the house, whichever is less. Ask whether 155.064(B)’s 800 sq ft minimum applies to ADUs. Phone 406-377-3318.
Sidney	Allowed with conditions	Capped at 1,200 sq ft under 11-17-2.B.6. Ask which cap governs; R-1 requires 7,200 sq ft lots, and separate sale is prohibited. Phone 406-433-2809.

Unincorporated county land

County ADU law binds only land zoned under the county zoning part. Unzoned land has no zoning rule: septic permits, applicable state sanitation review, state permits and private covenants decide. Call the county sanitarian.

County (unincorporated)	Detached ADU	What the local rule says
Gallatin County rural Bozeman and Belgrade, Four Corners, Gallatin Gateway, Bridger Canyon, Big Sky’s Gallatin side, Hebgen Lake, Three Forks and Manhattan surroundings	Allowed with conditions	Caps differ by district: 1,200 sq ft under one acre and 2,000 above in the Bozeman Donut (15.02), 1,000 in Big Sky, 1,200 in Bridger Canyon. Septic and DEQ review apply. Phone 406-582-3130.
Madison County Big Sky’s Madison side, Ennis and Madison Valley outskirts, Cameron, Alder, Harrison, Pony, Norris, Ruby Valley around Sheridan and Twin Bridges	Ask first	No size cap or zoning. Ask the sanitarian about septic capacity, sanitation review and the construction permit under Ord. 2-2006. Phone 406-898-4331. Source: 2025 Madison County Growth Policy (no county zoning adopted)
Beaverhead County Dillon outskirts, Wise River, Polaris, Jackson, Wisdom, Dell, Lima area, Grasshopper and Big Hole valleys	Ask first	No size cap or zoning. Ask the sanitarian about septic capacity, sanitation review and the construction permit under Ord. 2-2006. Phone 406-898-4331. Source: Beaverhead County Growth Policy Update, adopted November 7, 2022 (no zoning regulations in effect)
Sweet Grass County Big Timber outskirts, McLeod, Greycliff, Melville, Reed Point area	Ask first	Outside Big Timber’s zoning area there is no size cap. Inside it, a detached ADU is not a listed use, and Table 4.1 sets 700 and 1,000 sq ft minimums. Septic approval remains. Phone 406-932-5470.
Stillwater County Columbus outskirts, Absarokee, Fishtail, Nye, Park City, Reed Point, Rapelje, Molt	Ask first	No size cap under Sec. IV. Ask how the county applies 76-2-215 because its ADU draft lacks confirmed adoption; septic approval remains required. Phone 406-322-8050.
Park County Paradise Valley, Gardiner, Cooke City, Silver Gate, Cokedale, Shields Valley	Ask first	Suce Creek has no size cap; Cooke City RRC and RRC1 cap at 1,000 sq ft under Ch. VI. Ask which district applies; septic limits remain. Phone 406-222-4102. Source: Suce Creek Planning and Zoning District Regulation, adopted August 2025, Sec. 7.B (accessory dwelling unit by right); the county’s Zoning page lists the other six district regulations
Carbon County Red Lodge outskirts, Roberts, Roscoe, Belfry, Joliet, Edgar	Allowed with conditions	No size cap under Secs. IV-A.5, V-A. Septic authorization requires one acre per living unit and proof the parcel’s sanitation approval allows another dwelling. Phone 406-690-1933.
Lewis and Clark County Helena Valley, Fort Harrison, Canyon Ferry, Lincoln, Wolf Creek, Craig, Augusta	Allowed with conditions	Helena Valley has no size cap under 702.12.02, 802.12.02, 902.02.14. Septic approval comes first; ask about unread districts and RR’s 10-acre minimum. Phone 406-447-8374.
Jefferson County Montana City, Clancy, Jefferson City; Boulder, Basin, Cardwell, Whitehall outskirts	Ask first	No size cap. North Jefferson prints a hearing requirement under 2.2.3, 2.2.5; ask how county ADU law applies and obtain septic approval. Phone 406-225-4040.
Broadwater County Townsend outskirts, Canyon Ferry Lake shore, Winston, Toston, Radersburg	Ask first	No size cap found. Ask whether a petitioned zoning district exists; septic capacity, applicable DEQ review and covenants remain gates. Phone 406-266-9211. Source: Broadwater County Community Development and Planning (no county zoning regulation posted)
Powell County Deer Lodge outskirts, Elliston, Avon, Ovando, Helmville, Garrison, Gold Creek	Allowed with conditions	No size cap under Ch. IV-C, V-A to V-F. Published rules require a hearing and scrutinize rental occupancy; ask about state law and septic approval. Phone 406-846-9795.
Granite County Georgetown Lake, Hall, Maxville, Rock Creek	Ask first	No size cap found. Georgetown Lake permits non-paying guests only under X.P; ask about district approval and heights. Elsewhere septic approval remains a gate. Phone 406-859-7021.
Cascade County Black Eagle, Sun Prairie, Vaughn, Ulm, Monarch, Belt and Cascade outskirts	Allowed with conditions	No size cap. Under 7.2.4, 7.3.4, some districts require hearings; ask how state law applies. Septic approval comes first. Phone 406-454-6905.
Yellowstone County Lockwood and the ring around Billings, Laurel outskirts, Shepherd, Huntley, Worden, Custer	Ask first	Capped at 750 sq ft, or 80 percent of the house if that is less; 1,000 sq ft on lots over 20,000 sq ft (27-1009.G). Owner occupancy and deed restriction print; ask. Phone 406-657-8247.
Hill County Havre outskirts in the City-County Planning area, Rudyard, Hingham, Gildford, Kremlin, Box Elder outskirts	Ask first	Size cap unknown: planning-area zoning could not be read. Ask for current rules; adding septic load requires written approval. Phone 406-740-7250. Source: Hill County Planning Office (the county names its Zoning Regulations and the City-County Planning area zoning permit; the regulations themselves are not posted)
Fergus County Lewistown outskirts, Lewistown Heights, Hilger, Roy, Winifred, Denton, Moore and Grass Range surroundings	Ask first	No size cap or county zoning. Ask about the Development Permit before construction; septic capacity and applicable DEQ review decide. Phone 406-535-9046.
Missoula County Lolo, Frenchtown, Seeley Lake, Condon, Bonner, Clinton, East Missoula, Evaro	Allowed with conditions	Capped at 980 sq ft and no larger than the house under 5.2.A.2. Public sewer or sanitation approval covering the ADU required under 5.2.A.4. Phone 406-258-4642.
Ravalli County Corvallis, Victor, Florence, the Bitterroot Valley outside Hamilton, Stevensville, Darby and Pinesdale	Ask first	No size cap outside citizen districts; district standards unread. Ask about district rules and septic approval under Regs 2.1. Phone 406-375-6530 (planning) or 406-375-6565 (sanitarian). Source: Ravalli County Planning: zoning (citizen-initiated zoning districts; no county-wide zoning)
Flathead County Bigfork, Lakeside, Somers, Evergreen, Marion, Hungry Horse, the North Fork	Allowed with conditions	Capped at 1,000 sq ft or 40 percent of the house, whichever is larger, under 8.05.160. Most lots need a DEQ certificate rewrite. Phone 406-751-8200.
Lake County Flathead Lake shores, Finley Point, Swan Lake, the Polson planning area	Allowed with conditions	Guest houses are capped at 1,000 sq ft in the zoned districts; larger units need conditional approval. Some districts, including XVII.CC, bar rentals or require owner occupancy. Septic approval is required. Phone 406-883-7235.
Lincoln County Fortine, Trego, Yaak, Rexford, Happy’s Inn, the Thompson Chain of Lakes	Ask first	No residential size cap or zoning. Ask the sanitarian about septic approval; rented second units need recorded sanitation review under BLR 6.B. Phone 406-283-2463. Source: Lincoln County Growth Policy Update 2019 (no zoning outside the Kootenai Business Park and airports)
Sanders County Trout Creek, Noxon, Heron, Paradise, Dixon, Lonepine, Camas Prairie	Ask first	No size cap or zoning. Ask about wastewater approval under 3(A)(2); rented units need recorded sanitation review under BLR 5.D. Phone 406-827-6965 (Land Services) or 406-827-6961 (Environmental Health).
Mineral County St. Regis, De Borgia, Haugan, Saltese, and land outside the towns of Superior and Alberton	Ask first	No size cap or zoning. Ask about wastewater alteration approval under Regs 1.5(4), replacement drainfield space under 3.4.E and applicable sanitation review. Phone 406-822-3525.

Every municipality must allow detached ADUs; some codes still print older rules the state law overrides, so ask the city how it applies the law now. Ask-first cities: Three Forks, Big Timber, Butte-Silver Bow, East Helena, Dillon, Ennis, Deer Lodge, Stevensville, Laurel, Havre, Lewistown, Glendive. Counties: Madison, Beaverhead, Sweet Grass, Stillwater, Park, Jefferson, Broadwater, Granite, Yellowstone, Hill, Fergus, Ravalli, Lincoln, Sanders, Mineral. Unzoned land depends on septic, sanitation review and covenants.

Ask About My Lot

How large can your ADU be?

Cities must allow up to 1,000 sq ft or 75 percent of the house’s gross floor area, whichever is less. Bozeman, Missoula, Red Lodge and Sidney publish broader allowances. State law sets no height or story cap; zoned counties set size caps. Walker’s 1,165 sq ft needs a broader local allowance.

House minimums at 75 percent (sq ft): 497 needs 663, 580 needs 774, 638 needs 851, 696 needs 928, 718 needs 958, 793 needs 1,058 and 989 needs 1,319. The Rabbit 1000 is 1,002 sq ft, 2 sq ft over: ask how the office measures floor area.

Plan	Size	Rooms	Footprint
Mysa 500	497 sq ft	1 bed, 1 bath	14 ft x 36 ft
Cabana 500	497 sq ft	1 bed, 1 bath	14 ft x 36 ft
Sledhaus 500	580 sq ft	1 bed, 1 bath	14 ft x 45 ft with deck
Cabana 700	718 sq ft	2 bed, 1 to 2 bath	14 ft 6 in x 49 ft 6 in (638 sq ft, 44 ft with one bath)
Torrey Flats	696 sq ft	1 bed, 1 bath	15 ft x 48 ft
Morada 800	793 sq ft	1 to 2 bed, 1 to 2 bath	39 ft x 21 ft
Morada 1000	989 sq ft	1 to 2 bed, 1 to 2 bath	43 ft x 24 ft
Rabbit 1000	1,002 sq ft	2 bed, 2 bath	34 ft 8 in x 14 ft 6 in, two story
Walker	1,165 sq ft	2 bed, 2 bath	42 ft x 27 ft

Nine Irontown ADU plans for Montana

These Multi-State Designer Series starting prices apply to Montana. Irontown’s ADU plans are designed to the International Residential Code, the residential code Montana adopts by state rule. Modern, Balance and Rustic finishes are priced in your quote.

Mysa 500

497 sq ft · 1 bed, 1 bath · from $142,600

497 sq ft, one bedroom, one bath. From $142,600.

See the Mysa 500 plan

Cabana 500

497 sq ft · 1 bed, 1 bath · from $184,400

497 sq ft, one bedroom, one bath, sloped roof. From $184,400.

See the Cabana 500 plan

Sledhaus 500

580 sq ft · 1 bed, 1 bath · from $179,300

580 sq ft, one bedroom, one bath, included front deck. From $179,300.

See the Sledhaus 500 plan

Cabana 700

718 sq ft · 2 bed, 1 to 2 bath · from $176,200

638 or 718 sq ft, two bedrooms, one or two baths. From $176,200.

See the Cabana 700 plan

Torrey Flats

696 sq ft · 1 bed, 1 bath · from $193,700

696 sq ft, one bedroom, one bath, open living area. From $193,700.

See the Torrey Flats plan

Morada 800

793 sq ft · 1 to 2 bed, 1 to 2 bath · from $242,400

793 sq ft, one to two bedrooms and baths. From $242,400.

See the Morada 800 plan

Morada 1000

989 sq ft · 1 to 2 bed, 1 to 2 bath · from $247,700

989 sq ft, one to two bedrooms and baths. From $247,700.

See the Morada 1000 plan

Rabbit 1000

1,002 sq ft · 2 bed, 2 bath · from $239,400

1,002 sq ft, two stories, two bedrooms, two baths. From $239,400.

See the Rabbit 1000 plan

Walker

1,165 sq ft · 2 bed, 2 bath · from $276,800

1,165 sq ft, two bedrooms, two baths, one story. From $276,800.

See the Walker plan

Home price and delivery to Montana

Multi-State starting prices include Designer finishes, module delivery and standard crane set for the first 250 miles from Spanish Fork. All Montana lies beyond them. Approximate extra transportation per load: West Yellowstone $1,500; Bozeman $2,700; Missoula $4,100; Billings $4,500; Kalispell $5,500.

Nearest townPlanTruckloads (estimated)

Approximate road miles from the factory

Estimated delivery beyond the 250 included miles

Starting price, delivered and set, plus estimated extra miles

Estimate only. Multi-State Designer Series starting price with standard delivery and crane set. Beyond 250 miles the rate is $12.75 per mile per truckload; plans wider than about 15 ft and two-story plans usually ship as two modules, and your quote confirms the count. Foundation, site work, stitch, utilities, permits, fees, engineering, pilot cars and sales tax are not included.

Beyond 250 miles, delivery costs $12.75 per mile per truckload, plus a pilot car if the permit requires it. Single-module plans use one load; bigger plans arrive as two modules on two trucks, stitched on your foundation. The calculator has a truckloads selector. Your written quote confirms loads, pricing, finishes, transportation and tax treatment.

Costs not in the home price

These costs come on top of the home price and are quoted by your general contractor, city and county, not MCO.

Site preparation, grading and foundation engineering
Foundation construction
Utility trenches, connections and capacity charges
Module stitching and finishing
Steps, porches, decks and landscaping
Permits, plan review and inspections
Septic permits and applicable sanitation review
Transport touch-ups
Any applicable tax

Cities and counties that zone under the county zoning part cannot assess ADU construction impact fees. Application fees cap at $250, plus usual building, review and inspection fees. Utility connection, capacity and system development charges remain local under 7-6-1601. Dillon publishes $725 water and $1,120 sewer development charges. Bozeman still prints impact fees; ask how the ban applies. Water and sewer connections can be the largest fee item. Ask your city or county which fees an ADU pays.

The Montana Department of Revenue states that Montana does not have a general-use sales tax. Nightly rentals under 30 days pay state lodging taxes. A modular home on a permanent foundation is real property; the county assessor sets its added value for property tax. Your written quote shows any tax that applies to the sale.

Living in or renting your ADU

Cities and counties that zone under the county zoning part cannot require owner occupancy or family relationships. The statutes leave long-term rental terms and separate sale unaddressed. Short-term rental rules stay local; stays under 30 days pay lodging taxes. Private covenants and HOA restrictions are preserved, so read your declaration before ordering.

Belgrade still prints owner occupancy. Polson prints owner occupancy and a deed restriction when renting. Lake County districts include rental bans or owner occupancy; Kalispell prohibits rentals under 30 days. Montana’s Supreme Court upheld the city ADU law in 2026. Ask how each office applies it now.

Plans, factory review and site permits

Submit stamped plans to your local building department, where one exists. Irontown’s feasibility review confirms how Montana’s factory-built review applies to your site.

Every city and town approves ADUs by right, without hearings. Review times: Anaconda-Deer Lodge 20 business days; East Helena 30 working days.
Irontown supplies engineered stamped plans designed for your site’s snow load, wind and applicable wildfire rules.
Irontown Homes (KEB Homes LLC) is on the Department of Labor and Industry’s approved factory-built building manufacturer list.
Certified departments permit and inspect foundations, utilities, set and stitch; elsewhere state electrical, plumbing and county septic permits are gates.
Complete applicable septic, sanitation review, well, floodplain, wildfire and covenant steps. Septic approval is separate from zoning; resolve well capacity early.

Irontown’s timeline

Irontown gives these durations for its three phases. Local permit review adds time. Septic, sanitation review, site readiness and weather can affect delivery; your city and contractor set their own schedules.

Phase 1 Feasibility Review (1 to 2 weeks). A $2,000 review, credited to the final contract, covers site access, route, budget, requirements, schedule and contractor support.
Phase 2 Pre-construction Agreement (2 to 3 months). Irontown visits your site, develops stamped plans, addresses site loads and helps you select finishes.
Phase 3 Construction and Delivery (12 to 16 weeks). Irontown builds, ships and sets the modules, communicating any permit, building or site delays.

Six steps on your property

Your general contractor coordinates site work with Irontown’s delivery and crane set. The contractor sets the schedule for these steps.

Pre-construction. Evaluate and prepare the site, obtain permits and coordinate delivery.
Foundation and utilities. Build the engineered foundation and install utility connections.
Module delivery and installation. Prepare access, inspect arriving modules and coordinate crane placement.
Stitching and finishing. Connect modules, finish seams, weatherproof and connect building systems.
Post-construction. Complete inspections, system testing, punch list and your walkthrough.
Ongoing support. Arrange warranty service and maintenance guidance when needed.

You need a general contractor

On-site work requires a general contractor licensed by Montana’s Department of Labor and Industry, priced separately. Registration became a Department licence January 1, 2026. Irontown has connections to some contractors; contact MCO to see whether we can recommend one for your area. Its feasibility review includes contractor support.

Building ADUs for your clients? Email support@mycozyoutdoors.com to join the MCO contractor network.

How to order through MCO

Choose your plan. Share your location, intended use and preferred finish series with MCO.
Request your quote. Get free zoning guidance sharing the rules MCO found.
Confirm first. Before ordering, confirm zoning, permits, fees and covenants with local planning, and septic and well capacity with your county sanitarian.
Start feasibility. Review access, delivery, budget and contractor support with Irontown.
Finalize your order. Irontown’s written contract confirms your home, options and delivery; your general contractor prices site work separately.

Visit the Spanish Fork factory

Visit Spanish Fork, Utah, about an hour south of Salt Lake City International Airport, with direct flights from Bozeman, Missoula, Billings and Kalispell. Walk finished modules on the line and see the finish series.

Schedule a Factory Visit

Common Questions

Does my city have to allow a detached ADU?

Every city and town must allow at least one ADU by right on a lot with a single-family house, including detached units. State law is not a permit for your particular plan. Building, health and covenant rules still apply.

How big can my ADU be?

The municipal guarantee reaches 1,000 sq ft or 75 percent of your house’s gross floor area, whichever is less. Cities may allow more. Counties that zone under the county zoning part set their own caps; unzoned land has no zoning size cap.

Can I rent it out without living on the property?

City law and the county law, where a county zones, prohibit owner-occupancy requirements. Short-term rental rules remain local, and private covenants remain relevant. Some published codes still print owner occupancy or rental restrictions; ask the office which rules it applies.

What will my ADU cost all in?

There is no single project total. Add your home’s quoted price and transportation to your contractor’s site-work quote, applicable permits, utility charges and tax. MCO quotes the home through Irontown; your contractor and local offices price the other work.

How long does it take?

Irontown lists 1 to 2 weeks for feasibility, 2 to 3 months for pre-construction, and 12 to 16 weeks for construction and delivery. Local permit review adds time, and site or sanitation requirements can affect the schedule.

Do I need a contractor?

Yes. A Montana Department of Labor and Industry licensed general contractor handles the foundation, utilities, delivery coordination, stitching and finishing. That work is priced separately. Contact MCO to see whether we can recommend a contractor for your area.

Rules were read in September 2026. This summary is not legal advice or approval; rules change and local offices decide their application. MCO takes no responsibility for zoning, permits, impact fees, septic approval or code compliance. You are responsible for confirming these matters with city or county planning and building offices and the health department for septic, and obtaining required permits before ordering. MCO strongly recommends contacting those offices and can share code sections and suggested questions.