Roofing underlayment, also known as roofing felts, is an important part of sloped roofs. It serves as the barrier that helps prevent water infiltration in the event the shingles fail.
The underlayment is sandwiched between the outer roofing layer (asphalt shingle, standing seam metal or wood shake) and the roof deck. There are various types of underlayment, but the function is the same. Underlayment is installed on the roof deck using fasteners, and sealed at the seams using adhesive. The outer roofing layer then goes on top of the underlayment.
If installed correctly, the underlayment should prevent rainwater infiltration in case parts of the outer roof gets damaged or torn off. It’s important to remember that roofing underlayment isn’t a substitute for the outer roofing material. Therefore, a damaged roof must still undergo roof repair even if the underlayment is fully intact.
There are different types of underlayment used on different roofing systems:
Asphalt-saturated felts – Also known as “traditional” felts, asphalt-saturated felts are sheets of pulped fabric and recycled paper soaked in asphalt. This type of underlayment is similar to tar paper, and can be described as stiffer than other underlayment types. This can add impact resistance for certain kinds of roofs.
Rubberized asphalt – Despite the name, rubberized asphalt contains only a small amount of asphalt and is essentially sheets of rubber. Its elasticity is ideal for regions that experience climatic extremes. Unlike other underlayment types, rubberized asphalt is fully adhered to the roof deck using special adhesives, instead of fasteners.
Non-bitumen synthetic underlayment – This is the most common type of underlayment that’s used on today’s residential roofing systems. Made of polyethylene or polypropylene, non-bitumen synthetic underlayment resembles tarpaulin. Some types are made with “breathable” features, which allows moisture on the roofing deck to evaporate.
Christian Brothers Roofing is your leading provider of roof replacement and repair services. Give us call at (502) 244-0208, or fill out our contact form to schedule an appointment.
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