Can the 16 ft. SM-Rib Galvalume Steel 29-Gauge Roof/Siding Panel be installed directly over an asphalt shingled roof?

We do not recommend installing the 16 ft. SM-Rib Galvalume Steel 29-Gauge Roof/Siding Panel over shingles

We do not recommend installing the 16 ft. SM-Rib Galvalume Steel 29-Gauge Roof/Siding Panel over shingles because if moisture and heat gets trapped in between the existing roof and metal roof, it can cause rot and mold. Please check your building codes to see if it is allowed in your area.