The roofing underlayment is a secondary barrier that protects the roof deck from damage caused by water infiltration, in the event the outer roofing layer fails. Today, Sterling Exteriors discusses how underlayment works and what makes it so important.
How Roofing Underlayment Works
Underlayment is a sheet of material installed between the roof deck and the outer roofing material, which could be asphalt shingles, sheet metal or wood shakes. There are several types of underlayment, but each has the same purpose: to keep the roof deck dry if the outer roofing is punctured or torn off.
Underlayment is not meant to function as a “second” roof—you still need to have the outer roofing layer repaired in case of damage—but it can prevent water from penetrating to the roof deck in the event of shingle damage.
Types of Roofing Underlayment
The following are types of underlayment that can be installed on sloped roofing systems:
Asphalt-Saturated Felts — Roofers refer to asphalt-saturated underlayment as “traditional” felt, because it is made using traditional materials such as pulped fabric and recycled paper, then soaked in hot asphalt during manufacturing. Asphalt-saturated felts are stiffer than other types of underlayment, which helps improve the roof’s impact resistance.
Rubberized Asphalt — Despite its name, rubberized asphalt contains little asphalt. Its mostly rubber composition makes it far more elastic than asphalt, which is ideal for homes that experience extreme temperatures. While other types of underlayment are installed using fasteners like nails, rubberized asphalt is installed using adhesives.
Non-Bitumen Synthetic Underlayment — Most roofing systems today utilize non-bitumen synthetic underlayment, which is made of polyethylene or polypropylene. While it resembles tarpaulin, non-bitumen synthetic underlayment has other properties that benefit the roofing system. Manufacturers like GAF offer “breathable” underlayment, which wicks moisture from the outer side and lets moisture from the roof deck evaporate instead of trapping it.
Sterling Exteriors is your leading provider of residential roofing repair and installation services. Give us a call at (513) 685-8055. You can also fill out our contact form to schedule an appointment. We serve customers in Cincinnati, Loveland and Newtown, OH.