Bill:
Not always true! It is the building code that identifies the home, not the way it arrived on the site. Modular homes can also have steel undercarriages with wheels, axles and hitches. Sometimes manufactured homes can be hauled to a site. So back to the original building code followed while under construction in the factory.
Steven:
The building code affects the type of financing the home can receive, that is why it is so important. Each lender has some very specific requirements for the home, depending on the building code.
And just like any other appraisal assignment, comparables are what determine the value. So if your subject was built to HUD code, then other HUD code built homes are the appropriate comparables. If factory built to a site built code like UBC, CABO, BOAC, etc, then other factory built to site built codes are the appropriate comparables.
The appearance, construction quality, materials used in construction, the interior finish, etc, etc, is also very important. There is just as large of variance between factory built homes, whether they are HUD code or site built code, as there are with built on site homes. They can range from cheap aluminum finish to stucco, wood siding, brick or masonry veneer after arriving on site, composition roofing, tile, wood shake, etc. Interior can range from cheap paneling to very expensive textured drywall, expensive sold wood paneling, printed wallboard to expensive on site applied wallpaper, low grade sheet vinyl to ceramic tile, saltillo tile, hardwood, very expensive carpeted floors, mass produced kitchen cabinets out of heavy cardboard to in place custom solid wood cabinets, with formica to solid surface, granite, tile counter tops. Etc, etc, etc, etc. Factory built homes can be one or two story homes, with as many angles, varied footprint as a built on site home. As I state in my article on the naifa.com web site, factory built homes are not your grandfathers trailer or your fathers mobile home anymore.
So the first thing is to determine the building code, once that is identified and similar code homes for comparables are identified, then it is standard appraisal procedures and techniques from then on.