Having a metal roof installed is a great investment to boost your home value. Due to its high upfront cost, you want to make sure that you get the most out of it. One way to do so is to use underlayment. It is applied beneath the metal roof to serve as a waterproofing barrier. 

You might be tempted to skip using underlayment to save costs. However, skimping may cause endless headaches in the future. Your metal roof does need underlayment. It ensures seamless roofing installation and acts as an added layer of protection. Moreover, it helps metal roofs perform better for a very long time.

In this article, we have listed everything you need to know about underlayment. Read on for more details:

What is the Purpose of Underlayment?

There’s a popular misconception that underlayment is only an accessory and not a requirement for metal roofing. However, it does provide notable benefits for your home. When installed properly, it will prevent moisture from entering your attic space. Entrapped moisture accelerates the deterioration of roofing systems, including metal roofing. 

Without an underlayment in place, your home becomes more exposed to harsh elements. Roofing underlayment provides an extra barrier of protection during extreme temperatures.

Types of Underlayment For Metal Roofing

Finding the right type of underlayment is very important. You need to know the different types of underlayment available to choose the best option. Here are the most common metal roofing underlayment options for your metal roof system:


Typically used in residential applications, felt underlayment paper is made of organic materials like natural fibers, wood cellulose, and more. For waterproofing and durability purposes, it is saturated in asphalt. Using an adhesive coating on one side, the felt underlayment is then attached to the metal roof deck.

If you have a steep-sloped metal roof, then felt underlayment is the best choice for you. It is one of the most popular options because of its cheap price. It also comes in different thicknesses: 15-pound and 30-pound. The thicker the underlayment is, the stronger it stands against harsh weather.

Like any other material, felt underlayment has its drawbacks. It provides little resistance to air and moisture vapor, making it more prone to tearing. Given its cheap price, it doesn’t last long enough to endure high-temperature environments. When it absorbs water, the felt material gets wrinkled immediately. This is the true testament that cheaper isn’t always good.

Synthetic Sheet

Another option is the synthetic sheet made of polyethylene, polypropylene, or polymer. This type of underlayment is lighter and easier to install than felt paper. When attached to the roof deck using roofing caps, it forms an overall protective barrier.

Through new technology, synthetic underlayment offers durability and enhanced performance. Since it is made of polymers, it is resistant to tearing, moving, and kinds of damage. Moreover, synthetic can keep out moisture and tolerate high temperatures. It may be slightly more expensive but can last longer than cheaper options.

Self-Adhering Membrane

For steep slope roofing, self-adhering membrane underlayment is the most recommended material. It is also known as a peel-and-stick underlayment consisting of butyl-based adhesive. 

These are typically installed on the deck surface to prevent water entry from ice dams. Attic condensation can be a major problem since it can cause mold and rot. It’s best to use a self-adhering membrane when it comes to ice dam protection. 

Another benefit is it is easy to install even during windy conditions. There will be fewer wrinkles and curling than other underlayment materials. You can easily install it around roof eaves, ridges, valleys, and rising walls.

But then again, it’s not all advantages for self-adhering membranes. An improper installation can also result in the poor performance of the membrane itself. Likewise, removing peel-and-stick underlayment can be a tricky job. Consult with a professional metal roofing contractor if this option is perfect for your home.

Rubberized Asphalt

Aside from asphalt-saturated felt, there is another roofing underlayment that is also made of asphalt. With rubber polymer content, rubberized asphalt underlayment is also a peel-and-stick product that does not require fasteners. This type is fully waterproof, which makes it suitable for most metal roofing installations.

It features combined benefits of non-bitumen synthetic and asphalt-saturated underlayment. You may install this to protect your roofing system against water damage. However, you can expect to pay more than other underlayment materials.

Partner with the Right Metal Roofing Provider

Underlayment is a critical part of your roof installation process. You need to pick the most effective underlayment material to maximize your metal roof’s performance. While selecting the right underlayment is an important decision, choosing the right contractor is also necessary.

At Pittsburgh Metal Roofing, we have you covered! Our team showcases superior workmanship and expertise in everything we do. From underlayment to metal roof accessories, we know how to create the best possible roofing system for you.
If you have questions about the right underlayment type, get in touch with our staff. We will listen to your needs and make recommendations based on your roof type. Our company also offers metal roofing repairs and installations. Feel free to schedule a free consultation with us. We’d love to have the opportunity to work on your next metal roofing project!