Idaho is the first state to discuss RV’s, manufactured, modular and tiny houses in the same reference document.
In the pamphlet linked below, the state Division of Building discusses different types of houses and includes a nod to tiny!
How does all of this apply to Tiny Houses? If you are planning to build or purchase a
dwelling of any kind, including a “tiny house”, it must comply with the requirements of one of the classifications listed above.
For a “tiny house” classified as an RV, you may have challenges in obtaining planning and zoning approval. If the building is wider than 8½ feet it cannot be an RV but it can be a modular building. Contact the Recreational Vehicle Industry Association about compliance with the appropriate ANSI standards, 703.620.6003.
Use of the modular classification will require approvals and inspections similar
to those required for site built dwellings. Use of the modular building option is
intended for manufacturers but may be used by anyone.
Both site built and modular buildings must comply with minimum area requirements of the building code. The smallest a house can be and still meet these requirements is about 150 square feet of floor area.
The HUD manufactured home standard is intended for manufacturing facilities and is very difficult to apply to one time construction.