The Importance of Roofing Underlayment

The underlayment is your roof’s secret weapon against damage caused by moisture infiltration. Here’s a look at how underlayment works and what makes it an essential part of your roof.

How Does Underlayment Work?

Roofing underlayment is a sheet of material that goes between the roof deck and the outer roofing material. It works like a secondary barrier against moisture infiltration in the event that the outer roofing is damaged, punctured or torn off. The underlayment is typically fastened to the roof deck using fasteners with rubber or plastic gaskets and then sealed at the breaks in the roofing plane with leak barriers. Note that underlayment is not intended as a “second” roof. You will still need to call for repairs if the outer roof is damaged in any way.

Types of Underlayment

There are three types of underlayment that can be installed on sloped roofing systems.

• Asphalt-saturated felts, also known as “traditional” underlayment or simply “felts”, is the oldest type of underlayment used on roofs. It’s made of pulped fabric and recycled paper that’s soaked in hot asphalt. This type of underlayment is more rigid than others and is still very much in use in roof replacement today. Its rigidity lends impact resistance to the roof.
• Rubberized asphalt is an elastic type of underlayment. Despite its name, it’s made of rubber and contains only a small amount of asphalt. Its elastic properties make it ideal for use in extreme weather conditions. Rubberized asphalt is installed on the roof deck using adhesives instead of fasteners.
• Non-bitumen synthetic underlayment is the most common underlayment type used by today’s roofers. Most synthetic underlayments are made of woven or spun-bound polyethylene or polypropylene. It resembles tarpaulin, but lets the roof deck “breathe”; it lets moisture evaporate instead of trapping it.

Our roofers at American Roofing & Construction, LLC can help you choose the right kind of underlayment for your chosen roofing system. Give us a call at (910) 964-0114 or (919) 917-2118. You can also fill out our contact form to schedule a roof estimate or an appointment.