Mobile homeowners may often be faced with roof maintenance problems, such as leaking and rusting of the metal components. To preserve the roofing materials and to conserve energy, many owners build a roof overlay structure to catch the rainwater and snow that can accumulate on metal materials and lead to corrosion. This type of roof-over system can be built with simple materials and a few tools to help extend the life of the roof for years beyond its normal life expectancy.
Attach a safety harness anchor to the surface of the roof with its vacuum lock provided by compressed air then connect the safety harness to the anchor. Put on the harness according to the manufacturer's directions.
Measure along the entire length of each side of the mobile home. Cut 2-by-4 lumber to this length to create a wooden plate to fit along the top sides of the structure.
Nail the wood directly into the metal roof and the existing top plate beneath the roofing material. Space the nails 6 inches apart along the length of the wooden plate.
Caulk the points where the nails penetrate the roof material to avoid condensation and leakage from these areas.
Attach 2-by-8 inch lumber parallel to the previously attached end plates at the center of the roof with nails. These serve as the ridgepole for the roof overlay.
Cut enough roof joists from 2-by-6 inch lumber to fit from the end plates to the ridgepole and leave an additional 18 inches over the side for an overhang. The joists should be positioned 24 inches from center to center to allow sufficient room for insulation batting. Nail the joists securely to the end plates and ridgepole.
Roll out insulation batts in between the joints with the vapor barrier side face-down.
Lay particleboard sheathing over the joints. Nail it into position on top of the joists and space the nails 6 inches apart.
Install a full-length ridge vent along the peak and center it with the alignment guides. Position the vent so that it is flush with the end of the roof ridge. Insert an end plug into the vent end. Fasten the vent to the ridge with 2-inch roofing nails hammered into the pre-drilled holes. Add additional sections of vent as needed and cut the last section to fit with a utility knife then add the final end plug.
Lay out 15-pound roofing felt and nail to the particleboard. Drive in nails every 6 inches along the edges and seams and 12 inches within the middle areas.
Install fiberglass shingles on top of the felt and nail them in place as recommended by the manufacturer.