Sylvania Roofing: Article About Types Of Underlayment
A roof is a system of materials working together to keep moisture, a home's worst enemy, out of the home. Great emphasis is often placed on covering materials such as shingles and metal sheeting, but the underlayment also plays a vital role in the roof's lifespan and integrity. Knowledgeable Sylvania roofing professionals can help homeowners choose the best underlayment for their new roof.
Decking usually consists of sheets of plywood nailed to the rafters. The underlayment prevents moisture from getting between the decking seams and into the attic. It also prevents any water that might make it past the shingles from damaging the decking.
Traditional underlayment is called roofing felt. It consists of a nonwoven substrate saturated with asphalt. For this reason, it has often been called tarpaper. The roofing felt substrate can be either organic or fiberglass. Organic in this context refers to the fact that it is made from cellulose fibers, not a lack of chemicals in its preparation. It is installed in overlapping sheets and stapled down. However, high wind areas require a more aggressive type of fastener.
Felt underlayment is water resistant, not waterproof.
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This means that, should one or more shingles be blown off, the area is not fully protected from the weather. Additionally, the exposed area becomes a point of entry for all of the felt to absorb water, which can lead to decking problems. Furthermore, roofing felt deteriorates quickly when exposed to the sun's UV rays, making missing shingles an even more urgent repair need.
Over time, exposure to heat causes the asphalt that made the felt water resistant to break down. At this point, the underlayment has become brittle and absorbent and can no longer serve its purpose. The process is exacerbated by a roof that is heated from below because of a poorly ventilated attic.
Other types of underlayment do not have the same limitations as tarpaper. These materials are referred to as rubberized asphalt underlayment. They have the advantage of being waterproof and self sealing. This means that, unlike roofing felt, the fasteners used to install the underlayment do not also compromise the underlayment's ability to keep water out of the attic. Because they are an engineered product, these types of synthetic underlayment are often formulated with chemicals that make them heat resistant and able to withstand UV rays without breaking down. Should a shingle be blown off, the decking is protected for far longer.