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What Is Roof Underlayment and Why Do You Need It?

Close-up of residential roof

Is it time for a new roof? If so, you’re likely preoccupied with the basics – shingle and insulation types, for example. But there is one crucial roofing component that may be unfamiliar to many homeowners: roof underlayment. So, what is roof underlayment, and why do you need it?

What Is Roof Underlayment and Why Do You Need It?

Purpose of Roof Underlayment

As you might guess from the product’s name, roof underlayment is installed under your shingles, between the deck and roofing shingles. It serves several important purposes. First, the layer repels water, which reduces the risk of leaks, rot, moisture damage, and eventual mold. This crucial component also provides extra weather protection if you live in a volatile climate. Let’s put it this way: If you live in an area with heavy rain or snow, you know that your shingles can only go so far. Roof underlayment provides an added layer of protection to extend the life of your roof deck. Additionally, during an extreme weather event like a hurricane or tornado, your roof underlayment can guard your wood deck against the elements if your shingles are torn loose.

Types of Underlayment

Roof underlayment is an extremely important component of your roof – but how do you know which type of protective layer is right for your home? Let’s discuss the three basic types of underlayment your roofer will choose from:

  • Asphalt-Saturated Felt: Asphalt-saturated felt paper is one of the most common protective roofing materials used in residential homes. The base of the underlayment is made from either an organic or fiberglass substrate; the felt is then coated in asphalt to create a sturdy protective layer.
  • Rubberized Asphalt: Rubberized asphalt underlayment is popular for its self-adhering nature, which makes it flexible and easy to install. Rubberized asphalt is also self-sealing, making it highly compatible with fasteners like staples or nails.
  • Non-Bitumen Synthetic: Don’t be fooled by the lightweight nature of non-bitumen synthetic underlayment. This flexible, non-skid underlayment material is extremely sturdy, made from a versatile plastic polymer known as polypropylene. Synthetic underlayment is an effective moisture barrier, which means it won’t wrinkle or fall prey to fungal growth.

What to Expect During Installation

So, what can you expect during a roof underlayment installation? There are several things to know. First, as mentioned above, your roofing contractor will install this protective layer between your roof deck and shingles. Additionally, in many modern roofing systems, your contractor may install two different underlayment layers – a waterproof water membrane installed along your roof’s perimeter, and a tear-resistant material that covers exposed areas of the deck. While the installation of this protective layer is fairly straightforward, the process is definitely a job for a professional. Even the most experienced DIY-er should leave the underlayment to a trusted roofing contractor.


Put simply, underlayment is a protective layer between your roof deck and shingles. This crucial roof component keeps your roof deck and home interior safe from extreme weather, rot, and mold. Remember: Roof underlayment is a crucial roofing component, and installation should be left to the professionals.

If you live in southwest Missouri, contact Taylor-Made Roofing for help with your roofing needs. Our experts can help you explore new roofing options, maintain an older roof, perform emergency repairs, complete tear-offs and recovers, and perform remodeling services. With over 20 years of experience in residential and commercial roofing, Taylor-Made Roofing is a company that you can trust with all of your roofing needs. Our family-owned business offers quality services, a reassuring warranty, and free estimates. For more information regarding roofing options, please give us a call at 417-326-8778 or contact us online. We look forward to hearing from you!

Fully licensed and insured, Taylor-Made Roofing is ready to take care of your roof.
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