- All sides slope toward the ground. Two sides are triangular, while the other two sides are trapezoidal.
- The standard residential home with metal roofing will generally have identical pitch or slope on all sides.
Must I Remove The Existing Roof?
- Metal roofing can be installed over existing roofing, assuming the structure of the roof can sustain the weight. It adds a significant amount of weight and requires shoring of roof supports.
- The most effective means to install a metal roof is to remove the old roof, structure new support, and begin again.
Begin at the Top
A practical tool now comes into play-the tape measure. Before you can order materials, you must know the length of needed coverage between eave and ridgepole, the piece of wood that runs from front to back and supports the rafters.
- Picture the roof as a cross section in the shape of a triangle, longest side down. This is called a “truss,” and is alsothe “run distance.”
- Now measure the leg of the triangle which runs from each end of the run distance to the ridgepole. This is the “rise distance.” In our case, the rise distance is the same on both sides.
- From here,you can determine the square footage of your roof, and determine how much roofing material to order.
Adding to the Framework
Next comes the insulation layer. All roofs have moisture, therefore you want to block it from entering the sheathing.
The installation process begins at the edge. First, install edging around the entire roof overhang. This is done by nailing to the roof framework, and overhanging the edge of the gutter system.
Next, position the metal panels horizontally, square to the edge, and overhanging slightly. Once in place, secure the panels to the structure with washer-head screws (to keep out water) set a foot apart. It would be a good practice to snap a chalk line at each level to position the screws on the frame and create an attractive picture from the ground.
The Layout Process
Subsequent rows must overlap by at least an inch. In a particularly moist environment, silicone may be applied at the place of overlap; the pressure on the metal sheet will spread the silicone and create a seal.
Finally comes the flashing that covers the vertical joints. Where there is a ridge, that flashing can be bent to fit. Like the plates themselves, flashing pieces must overlap towards the bottom, for water flow.
On simple buildings where there is little concern for perfection, a DIY project is possible. For elaborate jobs with many joints, dormers, and varying roof styles, it is best to hire a metal roof installation professional.