When installing metal roofing, it will be held down with roofing screws, and in some cases flashing installed for asphalt roofing materials will also be secured using roofing screws. The length and style of screw being used will depend on the type of roof it is being used to secure as well as where on the roof it is being used.
For general metal use, self-tapping roofing screws can be used, usually three-inches long, however when securing the first edge of a metal roof section, a one-inch screw may do the job. If laying a metal roof over an existing single layer of asphalt, a three-inch screw will be needed on the first section as well. Unless each panel of a metal roof has been pre-drilled at the factory, or least weakened with dimples, a self-tapping screw will make the job easier and faster with less risk of injury due to snapping roofing screws.
Unlike nails driven through an asphalt shingle, there is nothing in the metal that will seal the hole as the roofing screws are installed. There are two basic types of roofing screws with sealer caps made of either metal, which sit on top of the metal roof and are held down tight by the screw, or rubber/plastic washers that are made as part of the screw that seal the hole as the screw is run in.
Different Gun Needed For Driving Screws
Installing a metal roof by hand is not recommended as the installation calls for a minimum of a screw every two feet. Doing this by hand would quickly wear thin on the installers hand and arm muscles. While rechargeable screw guns are available to drive roofing screws, due to the power requirements for the job, it would become necessary to change batteries at least once an hour. Considering charging times, a person would need at least four batteries to get through an eight-hour day.
An electric screw gun will supply the power needed throughout the day and most screw guns will have adjustments to insure the screw is not driven into the roof too far. In some cases the heads of roofing screws could be drawn in too far damaging the new roof or the heap can be snapped off the screw.
A pneumatic screw gun can also be used but like an air-powered hammer, a compressor will be needed as well as a long rubber air hose will need to be dragged along with it while installing roofing screws into the new roof.
