Are modular homes are of inferior quality when compared to site built homes?

No - and arguably modular homes are of better quality. The two primary reasons for this are supervision and weather. Site built homes are subject to the elements. Modular homes are built in the controlled environment of the factory. This protects building materials from the harsh outdoor environment and enables laborers to work in comfortable environs improving the quality of their work. The second reason for the better quality of modular homes is the quality control programs used by modular manufacturers. Few builders who construct site built homes have a quality control manual or program in place. Modular builders do. Furthermore, regular inspections occur during the building of a modular home. In theory this is what your builder is supposed to do in the oversight of his subcontractors. In practice however these types of inspection are not done frequently or as well as it should be. Modular homes are inspected once on the assembly line, once more by a third party independent inspector required by the state in which the home is to be built, and lastly by the local building inspector – for quality, as well as form, fit and accuracy.