It's imperative to know local laws and avoid unnecessary fines and penalties if you're considering building or purchasing a tiny home or accessory dwelling unit (ADU) in Montana.

While tiny homes are legal in the State of Montana, requirements vary across different jurisdictions. The state has adopted Appendix Q from the International Residential Code (IRC) as its minimum requirement for tiny houses. 

However, building and zoning regulations across the state make it a potential minefield if you're unaware of the regulatory landscape. 

In this article, we'll provide a comprehensive overview of tiny house regulations in Montana. 

The article covers multiple scenarios and types of tiny homes to ensure you're on the right side of tiny house laws at every step of the building or purchasing process. 

Are tiny houses legal in Montana?

Tiny houses are legal in Montana. On the 7th of December 2019, the state adopted Appendix Q, the tiny house requirements drafted by the International Residential Code (IRC). Certified local jurisdictions in the state may adopt the same minimum requirements as part of their building code. 

The IRC sets the “minimum standards and requirements for detached one- or two-family dwellings and multiple single-family dwellings and their accessory buildings.” 

These requirements are known as Appendix Q. The State of Montana has made several amendments to tailor the requirements to local realities. 

Tiny houses, per the definition of Appendix Q, include all single-family dwelling buildings built on a permanent foundation with a floor area of 400 square feet. 

Appendix Q stipulates the minimum dimensions and requirements for different parts of a tiny house, including ceiling height, emergency escape, loft area, various rooms, stairways, and more.

Furthermore, The Treasure State has clarified that you cannot use tiny homes for commercial or business purposes. You can rent out tiny homes for 30 days minimum; you cannot use the unit for Airbnb-style rentals. 

What kind of tiny houses are permitted in Montana?

Montana permits different kinds of tiny houses, particularly those built from scratch and factory-built buildings mounted on permanent foundations. 

Are tiny houses on foundation permitted in Montana?

The State of Montana permits tiny houses mounted on permanent foundations as long as they meet the requirements and standards in Appendix Q of the International Residential Code (IRC) family dwelling framework. 

The tiny homes must also meet local tiny house and building code requirements, as most jurisdictions have varying standards and expectations. 

For example, Livingston defines tiny homes with a maximum of 400 square feet, while Bozeman and Missoula peg tiny homes as dwelling units under 600 square feet. 

Are Tiny Houses on Wheels permitted in Montana?

There isn’t clear regulation on tiny homes on wheels in the State of Montana. Adopted rule 24.301.154 announcing the adoption of Appendix Q mentions only tiny houses installed on permanent foundations but is silent on tiny houses on wheels. 

House Bill 494 sought to address this gap, but the bill did not pass. 

The bill would have classified tiny homes on wheels as travel trailers whenever they are in transit and give cities the power to tax them as other residential properties. 

Tiny homes on wheels are seen equally as recreational vehicles (RVs) in most Montana communities and are not considered primary residences. 

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What does a tiny house need to be up to Montana building codes?

As stated above, tiny houses in Montana must conform to the standards and requirements outlined in Appendix Q by the IRC. 

Counties and cities in the state build on this framework and may have additional requirements. 

You must consult with local zoning laws and a tiny house builder to get a lay of the local rules and requirements. 

Rules for permanent structures

The minimum requirement incorporated by the State of Montana for permanent structure is in Appendix Q by the IRC. 

Here are some of the major highlights to keep in mind when building or buying tiny homes in Montana:

• The tiny home must meet the standards of section R310, the “emergency escape and rescue opening requirements” framework by the IRC. 
• The ceiling height of all hallways and space must be at least 6 feet 8 inches. Sleeping lofts can have lesser ceiling height than this. The ceiling height must be a minimum of 6 feet 4 inches for bathrooms, kitchens, and toilet rooms. 
• Lofts must have a floor area of at least 35 square feet and a minimum horizontal dimension of 5 feet. 
• Stairways accessing lofts should have a width no less than 17 above the guardrail or 20 inches below. The headroom for the same must be at least 6 feet 2 inches. 
• The height for risers for stairways accessing lofts must be between 7 and 12 inches. 
• All local ordinances regarding other features like setbacks, building height, foundations, and parking apply. 

Furthermore, each tiny house you build must adhere to the residential building code of the local jurisdiction. Local rules and regulations trump that of the state for residential buildings with less than five dwelling units. 

You must build according to the State’s building code if the local jurisdiction has not adopted any building code. The same applies to tiny houses and all residential apartments.

That means Appendix Q applies as adopted by the State’s Department of Labor and Industry if a local jurisdiction has not adopted any local ordinances for tiny houses. 

Lastly, you must remove the towing tongue if you’re mounting the tiny house on wheels on a permanent foundation.

Rules for temporary tiny houses

The law in Montana only permits building tiny houses on permanent foundations. As such, you must mount your tiny house on a permanent foundation, even if you intend to live temporarily in the structure. 

Places like the City of Billings permit parking motor homes in the rear yard as long as you park it on an asphalt or concrete surface. 

In addition to the above information, you cannot live or sleep in such structures if stored or parked on residential lots for more than five consecutive days. 

Rules for transitional structures

For transitional structures like manufactured houses on wheels, the State of Montana requires that the product meets the standards set by the United States Department of Housing Land and Urban Development (HUD). 

The tiny house must have a certificate to prove this. 

All mobile homes or factory-built buildings with or less than 400 square feet or less in floor area, excluding lofts, qualify as tiny houses. 

Furthermore, the State notes that no “mobile home or vacation trailer shall be located anywhere within the corporate limits of the city except in a licensed mobile home park.” 

It bears repeating that a proposed bill sought to regulate tiny houses on wheels. The bill sought to recognize them as travel trailers while in transit and that tiny houses also qualify for the same taxes as mobile homes when used as a residence. 

However, the bill didn’t pass through the Montana State Legislature. The bill preceded the State’s adoption of Appendix Q. 

The summary is that: tiny houses on wheels are classified as RVs or travel trailers. You may park your transitional structure outside a licensed mobile home park for not more than 48 hours, provided the property is unoccupied. 

What Montana counties allow tiny houses?

Some areas in Montana have explicit regulations that allow for the construction of tiny houses, while others regulate them as part of Accessory Dwelling Units (ADUs). 

We examine some of the areas below and their specific guidelines.

The City of Missoula

• The City of Missoula permits tiny homes as ADUs. The structure must not be between 350 and 600 square feet to qualify as an ADU. The key rules and regulations include the following:
• You must build a detached ADU on a lot already occupied by a single-family residence. 
• The exterior materials you use for the tiny home must match that of the detached house. The same applies to the roof pitch and trim of the tiny house. 
• ADUs must not exceed 50% of the actual rear yard area of the lot. 
• There must be at least a 10-foot distance between the main building and the ADU. 
• All ADUs must not exceed 22 feet in height or the height of the primary building, whichever is smaller. 
• You’ll need to acquire a building permit from the City’s Development Services to build an ADU. 
• You do not require a zoning compliance permit if the dwelling unit is less than 120 square feet in area or 12 feet in height. 

Tiny house village regulations in Missoula

The City of Missoula also has specific regulations for tiny home developments or villages. Here are the main takeaways:

• All tiny home villages must not exceed 5 acres in size. 
• The yard size for each tiny home must be 1.5 “times the home’s gross floor area or 1,000 square feet, whichever is bigger.”
• You must mount the tiny homes on a permanent foundation and connect it to the city’s water and sewer system. 
• The tiny house village must have a maximum density of twenty tiny homes per acre.
• All tiny homes must conform to the city’s setback and height requirements for accessory structures.

The City of Bozeman

The City of Bozeman is one of the cities in Montana that has adopted Rule 24.301.154 and Appendix Q as passed by the State. 

Bozeman does not have a minimum required square footage for a tiny house - or a residential building, for that matter - as long as it meets the city’s building code requirements. 

That said, tiny homes built as ADUs cannot exceed 600 square feet. 

The city is also considering several sweeping changes to its ADU regulations. The changes include relaxing the need for at least one off-street parking space and access to an alley. 

Tiny homes also feature in the City’s Community Housing Action Plan. Some highlights related to tiny homes include:

• Exploration of the incorporation of Moveable Tiny Homes in its code provisions. 
• Alter current utility and engineering standards to propel and encourage the construction of more tiny home villages. 

The City of Livingston

Like the City of Bozeman, Livingston has adopted Appendix Q as its de facto requirement for tiny homes. 

All tiny homes are also subject to all building and zoning ordinances for residential buildings, especially for setbacks and design. 

Furthermore, the City requires residents to install all tiny homes on a permanent foundation. Per the City’s ordinances, tiny homes are dwelling units below 400 square feet of gross floor area. 

The City also defines a permanent foundation as “a standard footing-type, perimeter foundation built to frost depth, with or without a basement.”

The City of Great Falls

The city has adopted the IRC 2021 version, but there’s no explicit indication that this includes Appendix Q, which provides a standard for tiny homes. 

The city also has regulations for factory-built or manufactured dwellings, including:

• Minimum roof pitch between 2 and 12
• Ceramic tiles, wood shingles, and fiberglass standing seam metal are suitable materials for roof coverings.
• Wood, vinyl, Exterior Insulation and Finish System (EIFS), and wood shingles are some of the approved materials for the siding. 
• You must fasten the building to a permanent foundation that meets all the most recent IRC requirements for residential structures. 

You may also like: How to Choose the Right Materials for Your Tiny House Construction

Can you permanently live in a tiny house in Montana?

The State of Montana and many local jurisdictions see tiny houses as a suitable solution to the challenges of providing affordable housing for residents. 

Tiny houses are seen as residential structures for permanent residence as long as they meet the prescribed local laws and Appendix Q requirements. 

How tiny can a house be in Montana?

There are tiny homes in Montana as small as 150 square feet. There’s no evidence the state enforces a minimum size of tiny houses. The state’s guidelines define tiny houses as residential structures with 400 square feet or below. 

Appendix Q of the 2018 IRC residential requirements defines tiny houses as residential structures with a square footage of 400 and below. 

Most local jurisdictions in Montana only prescribe a maximum size definition for tiny homes in all the ordinances we examined.

Examining the tiny house landscape shows structures as low as 150 square feet. 

The Housing First Village, a tiny house community in Bozeman, has homes within the range of 150-300 square feet in size. Human Resource Development Council (HRDC), a not-for-profit organization, built the project. 

Where can I build a tiny house in Montana?

Many options are available to build a tiny house in Montana, including an ADU, RV parks, or tiny house communities. However, each town building code jurisdiction has areas you can and cannot install a tiny house. 

For example, the City of Livingston does not permit tiny houses or villages in central business districts (CBD), light industrial, industrial, public, and neighborhood commercial districts. 

Also, most locations in Montana require that you plug your tiny home into the public water and sewer system. So, you have to consider the cost of doing so. 

Do I have to pay property taxes for my tiny house?

In the State of Montana, you’re liable for property taxes if you own the land where your tiny home is situated. Similarly, tiny houses placed on a foundation may also accrue local property taxes due to being classified as real property. 

Tiny house owners do not have to pay the same property taxes if their homes are on wheels because they’re classified as RV automobiles or mobile homes. Automobiles are not subject to local personal property tax. 

Installing a tiny house as an ADU will likely increase the property value, thus making them liable to property tax. While other states levy a sales tax on tiny houses, Montana doesn’t. 

It’s also important to stress that while tiny houses have been around for a long time, the idea of regulating tiny houses is still relatively new. As such, there may be ambiguity around if tiny houses qualify for property taxes in different locations. 

Where can I park a tiny house on wheels in Montana?

You can park a tiny house on wheels or mobile homes in a registered mobile park, tiny house communities, or a lot you purchased or rented. Tiny houses on wheels are generally considered RVs or mobile homes in the State of Montana.

Most cities or towns in Montana see tiny houses on wheels as recreational vehicles and treat them as such and not as dwelling units. That said, parking regulations vary per area. 

For example, you can park a tiny house on wheels in your rear yard in the City of Billings. 

However, you must park the tiny home on an asphalt or concrete surface. Furthermore, you cannot live or sleep in a tiny house for more than five consecutive days. 

On the other hand, Missoula permits you to temporarily park your unoccupied mobile homes outside a licensed mobile home park for 48 hours. 

Other than that, you're not allowed to park a mobile home within the corporate limits of the city. You must park your tiny house on wheels in a mobile home park. 

Can I build and put a tiny house in my backyard in Montana?

You can build and put a tiny house in your backyard in Montana as an accessory dwelling unit (ADU). You must, however, seek approval, maintain the number of ADUs per lot, follow restrictions on size, and adhere to owner-occupancy requirements.

In addition to the above, the tiny house must meet local requirements. For example, Bozeman has the following major requirements:

• The property owner must stay in either the primary or accessory building.
• The ADU cannot exceed 600 square feet and must have one bedroom.
• Only a maximum of two persons can occupy the ADU.

In Missoula, lot size and district determine if you can build a tiny house in your backyard. For instance, you’ll need a lot size of 5,400 square feet in the R5.4 district to be eligible for an ADU in Missoula. 

The nuances across the State are not one size fits all. You must still do due diligence to ensure you’re not flouting any law. 

How much does it cost to build a Tiny House in Montana?

The average cost of building a tiny house varies across the State of Montana. The cost of a tiny home in Montana ranges from just over $51,000 in Missoula to approximately $57,500 in Helena. 

The minimum price paid for a tiny house in Montana ranges from $11,010 in Missoula to $12,315. From the available data, it seems it’s cheaper to build a tiny house in Missoula. 

Remember that these are just estimates. You can get tiny houses built for less or more than the average price. 

Before embarking on a self-built tiny house, it’s best to consult with professionals to ensure you get a place you love that meets the requirements of local laws.

Various factors affect the cost of building a tiny house, including:

• Size
• Quality of amenities
• Permits
• Materials and supply
• Cost of hiring tiny house builders
• Inspection and building fees

You may also like: tiny homes between $20-40k.

Are there tiny home communities in Montana?

There are several communities in the State of Montana for tiny house enthusiasts or those looking for where to temporarily or permanently install their homes. 

Examples of such communities include:

• Tiny Homes Village at St. Mary
• The Housing First Village
• The William Booth Village

Ensure that any tiny home community you join is licensed and built up to the standard required by the city or town. 

Why are Montana residents exploring tiny homes & park model homes?

Montana is suffering from two challenges: housing affordability and availability. Between the first half of 2020 and the first half of 2022, home prices increased by 50% in Montana. 

Between two years prior, home prices grew by 13%. Montana ranks fifth on the list of states with the highest home value increase since the pandemic.  

Suffice it to say that the rising prices have created a barrier for first-time homebuyers. It’s easy to see why: the average income in Montana is lower than the national average, but house prices are higher than the United States average. 

According to the Montana Department of Labor Economy, the soaring house prices is primarily due to demand outstripping supply.

The National Housing Low Income Coalition also notes that Montana has a shortage of affordable rental homes, forcing many low-income families to spend over 50% of their income on rent. 

All these issues contribute greatly to why many residents are looking at tiny homes as cheaper alternatives. 

Many cities and towns in the State also consider tiny houses and accessory dwelling units as one of the key strategies to curb homelessness and the scarcity of affordable housing. 

However, in some areas, residents push back against tiny home villages. The two reasons for the resistance by residents are fear of declining property values and a potential uptick in crime. 

Takeaway: Learn the key tiny house rules in Montana before moving into one

Tiny houses are legal in Montana. The State adopted Appendix Q by the IRC to provide a base framework for tiny house standards in the State. 

Different cities like Great Falls, Bozeman, and Livingston have adopted the guidelines with existing residential buildings and zoning ordinances. 

The tiny house movement has continued to grow in popularity in the State of Montana due to skyrocketing house prices and the lack of affordable rental housing. 

Despite this, it’s important to slow down and choose locations favorable toward tiny houses. That way, you can build the tiny home of your dreams without any future rancor. 

Not sure where to start with building your tiny house? Get started with this practical guide: How to Build a Tiny House.