Metal roofing is a commonly used material for several reasons ranging from low cost to durability. The installation of metal roofing is often easier and faster than other roof types, and because of its simple design and generally large size, can actually be installed directly on top of existing roofing materials like asphalt shingles and foam roofing. Installing metal roofing over existing roofing material can usually be successfully completed using simple tools.
Things You'll Need
Metal roofing panels and caps
Roofing fasteners (may differ per roofing panel style; screws, nails, etc)
Electric screw gun or roofing hammer (depending on required fasteners)
Circular saw with abrasive blade
Tape measure (optional)
Chalk line (optional)
Work gloves (optional)
Safety glasses (optional)
Ladder (if necessary)
Lay a metal roofing panel over the existing roof material in the bottom corner of the roof surface, and fasten to the roof according to the metal panel instructions; metal roofing materials are available in several styles that require different fastening applications, but are most commonly screwed to the roof framing or sheathing material, which in the case of installing over existing roofing material, should be fastened using 2-1/2-inch screws.
Lay the next panel toward the roof ridge, overlapping the first panel 2 to 4 inches (unless otherwise noted per panel requirements), and fasten according to panel installation instructions. Continue setting panels to the roof ridge, cutting the last panel with the circular saw if necessary. Repeat for the following rows to the other end of the roof.
Repeat steps 1 and 2 on other roof faces, and add a roof ridge cap when finished (this is a v-shaped metal panel that matches the contour of the metal roofing panels).
For roofs without plywood sheathing (underneath the existing roofing material), measure and mark the roof rafters using the tape measure and chalk line (rafter spacing is usually 24 inches on center from the roof edges) or an electronic stud finder.
Wearing work gloves can prevent cuts on your hands when working with metal roofing panels, as they often have sharp edges, and wearing safety glasses can prevent eye damage when cutting metal panels.
Use caution when working and walking on the roof; wear appropriate work shoes to avoid slipping.