Roofing underlayment is a part of sloped residential and commercial roofing systems that protects the roof deck from water infiltration. It functions as a secondary barrier in the event the outer roofing layer fails. In this blog, roofing company Universal Roofing & Exteriors shares a look at what makes underlayment an indispensable part of every roofing system.
How Roofing Underlayment Works
Underlayment, or felts, is installed between the outer roofing material—asphalt shingles, sheet metal, or wood shakes, to name a few—and the roof deck. There is more than one type of underlayment (which we will discuss in detail later), but the function is essentially the same: keeping the roof deck dry in case the roof gets punctured or damaged.
The underlayment is installed over the roof deck using specially-designed fasteners, while the seams are sealed using adhesive. While it can prevent rainwater infiltration efficiently, underlayment is never a substitute for the outer roofing material. Damaged outer roofing must still undergo roof repair even if the underlayment is intact.
Types of Underlayment
The following are the different types of underlayment in use today:
Asphalt-Saturated Felts — Often referred to as “traditional” felts, this type of underlayment is made of pulped fabric and recycled paper soaked in asphalt. Asphalt-saturated felts are stiffer than other underlayment types, which can help improve impact resistance for some roofing systems.
Rubberized Asphalt — Despite its name, this type of underlayment doesn’t contain much asphalt; it’s basically sheets of rubber. Rubberized asphalt is far more elastic than other options, which makes it ideal for regions that experience extreme heat and cold. Unlike other types of underlayment, rubberized asphalt is fully adhered to the roof deck.
Non-Bitumen Synthetic Underlayment — Most of today’s new roofs feature this type of underlayment, which is typically made of polyethylene or polypropylene. Non-bitumen synthetic underlayment resembles tarpaulin, but it has features that let the roof deck “breathe” and allow moisture underneath to evaporate.
Universal Roofing & Exteriors is your leading provider of roofing services, including drone roof inspections. Give us a call at (317) 257-0779 or fill out our contact form. We serve customers in Indianapolis, Fishers, and Zionsville, IN.