Proper insulation in mobile homes is even more important than in traditional homes because the bottom of the mobile home is exposed to the outside air. The insulation under a mobile home prevents heat loss through the floor, which increases the energy efficiency of the home. It is covered by a rigid board called a belly board or by a fabric-like air barrier. Installing insulation under a mobile home is usually performed by professionals, but can be done by homeowners if the proper procedure is followed.
Crawl underneath the mobile home at one end and lay on your back so you can easily work underneath the mobile home.
Remove the belly board from the mobile home by prying the edges loose with a crowbar or other flat object. Be careful not to damage the belly board, as it will be reinstalled later. The belly board is a thin, rigid board that covers the bottom of the home; it is usually installed in large sheets, much like sheet rock.
Place the insulation flat against the floor of the mobile home with the paper side facing upward. Attach it to the floor by placing wire under the insulation and securing the wire at the edges with nails or a staple gun. This task is much easier if two people do it: one holds the insulation while the other installs the wire mesh over it. Select a batt insulation that has an R value between 11 and 19.
Continue installing insulation and wire mesh until the entire bottom of the mobile home is covered.
Reinstall the belly board sheets by nailing or stapling them in place. If there was no belly board, install air-filtration cloth, available at home improvement stores. It comes in rolls and is attached to the bottom of the trailer using industrial-strength, double-sided tape.