Each manufactured home must be designed according to the federal Manufactured Home Construction and Safety Standards at 24 CFR 3280, commonly called the HUD Code. The HUD Code stipulates, at §3280.305(c)(3), that the home shall be designed and constructed to conform to one of three roof load zones. The appropriate roof load used in design is dependent on where the home will be initially installed. Homes designed and constructed to a higher Roof Load Zone can be installed in a lower Roof Load Zone (a home designed to a North Zone can be installed in a Middle or South Roof Load Zone). However, a South Roof Load Zone home cannot be installed in either a Middle or North Roof Load Zone.
Roof load (live load) design is affected by the shape of the roof whether it is flat, curved or pitched. Roof loads are a downward (vertical) force on the home. The North Zone, Middle Zone and the South Zone are identified on the roof load zone map above. This downward imposed load on the home is also known as the snow load. The North Zone design live load equates to 40 pounds per square foot, the Middle Zone equates to 30 pounds per square foot, and the South Zone equates to 20 pounds per square foot.