Belly board, also known as blackboard, shepherd board or a rodent barrier, is typically an asphalt-impregnated fiberboard, asphalt-impregnated fiberglass cloth, or heavy tar paper. The belly board serves to prevent moisture infiltration, insulate the subfloor and keep animals and insects from gaining access to your manufactured home.
Tears, holes or any area that sags in the belly board should be investigated and repaired promptly. Before you make repairs, assess the damage. If a moisture build-up was responsible for the problem, locate and repair the leak. You'll need to replace any damaged materials like insulation and flooring as well. If the tear was caused by pests, get rid of the animals and any nests they built.
To patch belly board, you'll need precut sections of repair material (available through manufactured home supply catalogs or stores), self-tapping coated screws, washers, some short 2 x 4 inch or 2 x 6 inch boards, hammer, screwdriver, saw, nails and utility knife.