Can the 12 ft. 5V Crimp Galvanized Steel 29-Gauge Roof Panel be installed over an existing roof with asphalt shingles?
It is possible to install metal roofing panels over existing asphalt shingles with the following notes.
Metal roofing panels may be installed over existing asphalt shingles, provided the roof decking integrity has been confirmed to be free of any moisture decay that would prevent un-levelness or fastener pull out capacity. NOTE: Ordinances regarding roofing applications over existing shingles vary by county and state. Check your local building code organization for more information. The panels may be applied directly over one layer of existing shingles, provided a separation sheet is installed on top to the shingles. We require a minimum 30# felt installed in the same direction as the panels. Metal roofing can also be separated from the moisture barrier by optional 1” x 3” battens as furring, spaced a maximum of 16” on center and fastened according to our recommended application details. CAUTION: Direct contact between pressure treated lumber and metal roofing must be avoided to prevent corrosion.