What is an Underlayment?

A new roof is much more than just shingles. It’s actually a complete system made up of many parts working together to provide strong waterproof protection for your home. One of the key components in any roofing system is the underlayment.

Underlayment is an extra layer of waterproofing protection that is installed on top of the roof deck and underneath the shingles. There are multiple types of underlayment that can be used with different types of roofing materials. Let’s look at the two main types and how they differ.

Asphalt-saturated felt. This is more commonly known as felt paper or tar paper and was the industry standard for underlayments until synthetic underlayments were introduced to the market. Asphalt is used to saturate the felt to provide enhanced water resistance and often it is reinforced with fiberglass.

Felt underlayment is more budget friendly but doesn’t provide the same level of protection that you will find with synthetic. It also cannot be left exposed to the elements for more than a few hours as the asphalt could leach out and reduce its water resistance. Felt underlayments are often attached to the roof deck using plastic cap nails.

Synthetic underlayment. This type of underlayment is made from polymers that are extremely durable, making this underlayment very tear resistant. It can withstand foot traffic on the roof while the final layer of roofing material is being installed and can be left exposed to the elements for weeks to a couple of months should there be a delay in getting the final roofing materials delivered and installed.

It typically installs faster since the rolls are longer and lighter than the asphalt-saturated felt and they are made to repel water, rather than absorb it as some felts might do. If you are installing a metal roof on your home, a synthetic felt underlayment can provide the high temperature resistance that is necessary for these roofs.

Choosing the right underlayment

As a GAF Master Elite contractor, we are able to offer a variety of options when it comes to choosing the right underlayment for your new roofing system. Our team of trusted roofing advisors will work with you to find the right system that will meet your budget and provide the ultimate protection for your home. Contact us today to schedule an appointment.

Photo credit: GAF