Are there differences in the permit requirements between site built and modular homes?

No, there are no differences. A modular home must conform or comply with the local building requirements of where the home will be placed. Mobile homes, in contrast, do have substantially different permit or code requirements - but these do not pertain to modular homes. Modular homes may cost less for permits because they are pre-inspected at the factory before ever arriving on the construction site. When you are looking at new homes, talk to a company that specializes in modular homes. They can answer questions as they pertain to your community and local codes.