Handy map of the US. Just click on your state (in the link, not on the picture) to see which building codes are in effect: http://www.iccsafe.org/about-icc/overview/international-code-adoptions/
The RVIA has provided a table showing regulations by state for park model RVs
What is a park model?
Below is a description from the RVIA:
On July 1, 2012, RVIA created a new membership category for manufacturers of park model RVs (PMRVs). A park model RV (also known as a recreational park trailer) is a trailer-type RV that is designed to provide temporary accommodation for recreation, camping or seasonal use. PMRVs are built on a single chassis, mounted on wheels and have a gross trailer area not exceeding 400 square feet in the set -up mode. They are certified by their manufacturers as complying with the ANSI A119.5 standard for recreational park trailers.
PMRVs are most often used in recreational vehicle campgrounds. They may be owned by the campground and rented to guests, or they may be brought in and used exclusively by their owners on a site rented or leased from the campground. They can also be placed by their owners on private property. These RVs are used for recreational purposes only. They are not meant to be permanently affixed to the property, they do not improve property values in any way, and they are neither designed nor intended by their manufacturers to be used as permanent residences.
Two different types of park model RVs are offered. One type is less than 8′ 6″ in width and is designed for frequent travel on the highways while the other and more popular type is wider than 8′ 6″ (usually 12′ in width), and must be transported with special movement permit. The 8′ 6″ unit typically is expandable when it reaches its destination utilizing slide-outs or tip-outs. The wider units, being less mobile, are usually sited in a resort or RV park location for an extended term, typically several years. Park model RVs are titled as vehicles by the various states. This is because PMRVs are built on permanent chassis such that they can be and are moved either within a campground or between campgrounds.
The City of Philadelphia specifies no minimum house size. However, houses must meet IRC 2009 (see below) and so must have at least one room of 120 square feet or more. In addition, the city requires that row houses (zone RSA5) align with neighboring houses along the front face.
IRC International Building Code 2009
SECTION R304 MINIMUM ROOM AREAS
R304.1 Minimum area. Every dwelling unit shall have at least one habitable room that shall have not less than 120 square feet (11 m2) of gross floor area.
R304.2 Other rooms. Other habitable rooms shall have a floor area of not less than 70 square feet (6.5 m2).
R304.3 Minimum dimensions. Habitable rooms shall not be less than 7 feet (2134 mm) in any horizontal dimension.
R304.4 Height effect on room area. Portions of a room with a sloping ceiling measuring less than 5 feet (1524 mm) or a furred ceiling measuring less than 7 feet (2134 mm) from the finished floor to the finished ceiling shall not be considered as contributing to the minimum required habitable area for that room.
Here are two sources of online codes:
- Municodes from the Nation’s leading legal publisher.
- The American Legal Publishing Company provides a free online library of state and municipal codes for most locations. Click on the map to go to the library and chose your state and city. Then search or scroll for descriptions of minimum lot sizes, setback rules, etc.
Information is available for all states except these 13: AL, CO, ID, KS, LA, MO, MS, ND, NV, UT, VT, WA, WY.