Certification of Tiny Houses on Wheels (THOWs)

To us, a tiny house on wheels is a home; to the government, it’s a recreational vehicle (RV). This is problematic because RVs aren’t considered legal residences. In addition, construction standards for RVs are set by the Recreational Vehicle Industry Association (RVIA) which charges several thousand dollars for membership. This is too costly and impractical for the owner-builder or small professional builder. Alternative construction guidelines are needed to promote safety and demonstrate that tiny houses are built to last. Starting in January 2015, we are going to offer a free, voluntary self-certification program for the most common types of tiny houses on wheels (THOWs). This certification will provide assurance that the tiny house has been built to agreed upon safety standards.

Initially, certification won’t be recognized by any government agency and won’t help with getting your tiny house registered or accepted into your desired neighborhood. However, in the long run, we hope that it will lead to certified THOWs being considered safe, sturdy, permanent, mobile residences.

The process and guidelines below are considered preliminary and are offered for public comment for the next two months. Your feedback is welcome.

Tiny houses that meet the Guidelines stated below can be self-certified by the builder by completing a documentation package that includes the following:

  1. Detailed structural plans illustrating the location of studs, joists, rafters, and engineered connectors (hurricane clips, tension ties, etc.). Plans must clearly address how the structure is secured to the trailer, and how the floors, walls, and roof are framed and sheathed. Plans must also include an illustration of a floor, wall and roof section, showing the building members, insulation, vapor barrier, moisture barrier, sheathing, siding and roofing.
  2. Detailed diagram of the electrical plan.
  3. Photographs of the framing, roof, insulation, rough plumbing, and rough electrical.
  4. Complete, detailed bill of materials. Where salvage or donated materials are used, the builder must provide a full description of the materials. It is recommended, but not required, that receipts be saved along with the bill of materials, as the DMV may request these when you register your THOW.
  5. A statement signed by the builder certifying the house is built according to THOW Guidelines.

These documents will be uploaded to and stored at a central, website (not yet available for use). Builders will have control over who may see their documents.

Definition & Guidelines
Definition: A tiny house on wheels (THOW), for the purposes of these Guidelines, is a structure which is intended as a full time residence or year-round rental property and meets these five conditions:

  1. built on a trailer that is registered with the builder’s local DMV.
  2. towable by a bumper hitch, frame-towing hitch, or fifth-wheel connection. Cannot move (and was not designed to be moved) under its own power.
  3. is no more than 8’6″ wide, 30′ long, and 13’6″ high.
  4. has at least 70 square feet of first floor interior living space, and no more than 255 square feet (excludes any lofts).
  5. includes basic functional areas that support normal daily routines (such as cooking, sleeping, and toiletry).

To be certified, a THOW (as defined above) must meet or exceed the standards found here.

certification of tiny houses on wheels

certification of tiny houses on wheels

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Elaine Walker

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