The Tiny House Movement

2018 IRC to include appendix for tiny houses installed on a permanent foundation
Julie Ruth
August 7, 2017
COLUMN : Code Arena | Codes & Standards

Most people consider owning a home to be the American dream. Typically, this home would include a kitchen, living room, dining room, family room, and multiple bedrooms and bathrooms. But some people dream of owning a “tiny home,” defined as a house that measures less than 400 square feet in area.

The reasons for wanting to own a tiny house are many. Some people point to their low price point. This group includes minimalists who reason that reducing the amount of resources one commits to housing frees up resources that can be used for other things. Other parties point to their “tiny” impact on the environment. Although the heating and cooling equipment might not be as efficient as traditional HVAC systems and the building envelope might not be as well insulated, tiny houses potentially use much less energy than traditional homes due to their small size. They also require significantly less materials to build, further reducing their demand on natural resources.

Then there is the potential mobility of a tiny house. They are often built within the highway height and width restrictions of a truck or trailer, with the intent of being easily relocatable. Tiny houses have also been promoted as a cost-effective solution to homelessness in some jurisdictions. And, there appears to be a growing industry for tiny homes as rental units, with a number of resorts now offering tiny houses as vacation cabins.

Code conflicts

The life safety provisions of the International Residential Code are based upon a “standard” size single-family home. Although the IRC establishes minimum room sizes, it does not limit the total square footage of the home. The only maximum size restrictions are that it not exceed three stories in height above grade plane.

Some code officials have had difficulty determining the appropriate requirements for tiny houses in their jurisdiction. Since they are typically constructed as individual homes, they don’t fall within the scope of the HUD code for manufactured homes. If they are not installed on a permanent foundation, they do not fall within the scope of the IRC either. A standard for recreational vehicles does exist (ANSI A119.5, Recreational Park Trailer Standard) but is not referenced in any of the International Codes.

New tiny house appendix

To address the tiny house movement, the 2018 IRC will include an appendix for tiny houses that are installed on a permanent foundation. As an appendix, a jurisdiction can choose to adopt it, or not, when they adopt the 2018 IRC.

The primary provision of this appendix relative to fenestration will involve Emergency Escape and Rescue Openings. The IRC requires an EERO in every sleeping room.

In many tiny houses, the sleeping area is a loft that is open to the main floor area. The appendix will clarify that an opening on the main floor area that is open to the sleeping area, and that meets the code requirement for EERO (with regard to size, operability, etc.), will also satisfy the EERO requirement for the sleeping loft. The appendix further clarifies that this is also true for roof-access windows where the sill is within 44 inches of the loft floor.

Unless specifically addressed in the appendix, the provisions of the IRC apply to tiny houses. For example, the appendix does not contain provisions for a smaller exterior door. Therefore, the required exterior door opening would be 32 inches wide and 72 inches high, just as it is for any other single-family home.

Code Arena is brought to you by the America Architectural Manufacturers Association. Julie Ruth may be reached through AAMA at 847/303-5664 or via e-mail at