What do you need to know about Tiny Houses?

by Chuck Osterday

You hear about them on the news and read about them in blogs. The Tiny House Movement has garnered a lot of attention and interest over the last decade. Often touted as the solution to many of the problems we face today: financial concerns, retirement security, and environmental issues, Tiny House owners also face challenges of their own – zoning requirements and building codes are at the top of the list. Tiny homes are generally no more than 120 square feet, which does not meet many accepted building codes. For example, the 2012 IRC defines the standards for one and two family dwellings as:

R304.1 Every dwelling unit shall have at least one habitable room that shall have not less than 120 square feet of gross floor area

R304.2 Other habitable rooms shall have a floor area of not less than 70 square feet (except kitchens)

R304.3 Habitable rooms shall not be less than 7 feet in any horizontal dimension (except kitchens)

R304.4 Portions of a room with a sloping ceiling measuring less than 5 feet between floor and ceiling shall not be considered as contributing to the minimum required habitable area for that room.

R307 Toilet, bath and shower spaces shall be provided with minimum spacing requirements.

The recently updated 2015 International Residential Code removes many of the size requirements previously seen for one and two family dwellings, however, many states are still using the 2009 or 2012 IRC as the basis for their state building codes.

So how are tiny homes legal?

Many tiny homes are built on a chassis with wheels, and are classified as park models, or recreational vehicles. These are 400 square feet or less, and must comply with codes specific to park models and recreational vehicles, usually ANSI A119.5. If the tiny home is greater than 400 square feet, it must comply with HUD’s manufactured housing program. Some states, such as Minnesota and Idaho have released fact sheets, allowing tiny home owners to see what is required. 

Minnesota recently released their tiny home fact sheet which summarizes that if the tiny house does not:

• have a chassis and axles, or
• have a HUD manufactured home label, or
• have an RVIA park model label, then

It is either a pre-fabricated or industrialized modular building and is subject Minnesota Rules Chapters 1360 or 1361, or site-built subject to Minnesota Rules Chapter 1309.

Some tiny houses can be classified as an Accessory Dwelling Unit (ADU). ADU’s can be used as rental units, “mother-in-law cottages”, or caregiver dwellings. A good example is Sonoma County, California, where a caregiver dwelling is allowed in the backyard of a person who needs assistance.

As the tiny house movement continues to gain momentum, more states will follow Idaho and Minnesota’s examples and clarify their stance on tiny houses. NTA stays informed of all the latest changes and updates to the housing industry and building codes.  For more information on how NTA can help you with RV Approvals, HUD code, or modular structure compliance, contact us!