What's under your roof?
On the surface, a roof looks like a simple layering of shingles, but it's actually much more complex than the average homeowner may realize. The roof is a “system” composed of layers of different materials that work together to keep wind and weather out of your home. Each layer has a specific purpose that when combined with the other components, provides protection to your home. Each layer is critical and has a specific role:
Decking (Wood Sheathing)
The decking is the base on which everything else is laid. The decking material varies, but most homes have OSB (oriented strand board) or plywood, but other materials, such as polystyrene, concrete and metal decking is also used. The decking is attached with nails onto the rafters, creating the foundation of the roof system.
Underlayment is installed onto the decking, before the installation of the asphalt shingles. The most common type used today is “felt” – a durable paper, which is saturated with asphalt. It provides a temporary barrier against rain and wind before the shingles are installed and provides an extra layer of protection, in the case of broken or torn shingles. The underlayment is rolled onto the roof horizontally. The installation is begun at the bottom edge of the roof, and each layer of underlayment is rolled with a significant overlap, which helps water to shed downward without seeping through the seams.
The drip edge (also called eave flashing) consists of angled aluminum strips nailed into place over the underlayment on the sides of the roof at the edges and beneath the underlayment at the eaves. The drip edge prevents water from building up, guiding it over the eaves and into the gutters.
The shingles, whether they are asphalt, metal, clay or another material, are the “outer shell” of your home’s roofing system. This system, when installed and working properly, provides your home with the protection it needs to withstand all but the worst weather.
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