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What is Underlayment?

When the time comes to replace your roof, it’s not just new shingles that will be put into place. There are many other components that work together to create a safe, weather-proof covering for your home. One component of that is the underlayment. Though it doesn’t get the attention it should, it’s a critical component in keeping your home properly protected and dry.

What is Underlayment?

Underlayment is a type of barrier material placed directly on your roof’s structural component, called the roof deck. It sits on top of the wood structure, acting as a barrier between the elements and the wood under it. In many cases, the roof deck is made of plywood, OSB, or step sheathing. The roof deck is held onto the home by rafters and trusses.

The underlayment goes on top of this structure. It’s a layer of protection your home needs.

Why is Underlayment so Important to Your Roof?

There’s no doubt that a new roof deck is going to be strong, dry, and protective of the home. Yet, it’s still possible for moisture to get into the home when the deck materials are exposed. Roofing underlayment is a water-resistant covering that helps to keep everything under it – from the roof deck and trusses to your family below that – dry.

Roof underlayment offers other benefits, including:

It helps to provide protection to your home if the shingles tear away, such as in a high-wind storm or damage from something striking the surface.

It shields the roof from bad weather during the installation process. That means it provides protection before the roof shingles are put in place.

It also helps to minimize the amount of roof deck damage that occurs over the lifetime of your roof, including from ice dams that build up during the winter months.

In nearly all locations, an underlayment is necessary not just because of the way it helps but also because local building codes require it. Most shingle manufacturers also require that an underlayment is put in place.

Types of Underlayment Available

A number of types of roofing underlayment are available and selected based on the conditions at the property, budget, and other goals. When you hire a roof technician for roofing replacement, be sure to ask them what type of underlayment is being used and why.

Here’s a look at some of the most common types of underlayment used and why.

Asphalt-saturated Felt

Asphalt-saturated felt was a long-used type of underlayment. Chances are good you’ll see it on older roofs that have not been replaced in some time. It’s sometimes called felt paper or tar paper. There are various versions of it, each with different mixtures of components, including cellulose, bitumen, polyester, and asphalt. This is a versatile product that’s rather easy to use and offers good reliability.

Rubberized Asphalt

Rubberized asphalt is the high end in roofing underlayment in terms of costs. It has a higher amount of rubber polymers and asphalt in it, which is why the costs tend to be higher. However, the key benefit is that this creates a 100 percent waterproof seal for the roof. It is one of the best options for long-term use when absolute water protection is desired.

Synthetic Underlayment

Today, synthetic underlayment is one of the most commonly used products. It is very water resistant. That’s because it’s made up of an asphalt-saturated basemat that is then fortified with fiberglass mixtures. This unique combination of ingredients helps the underlayment become very water resistant. It is also stronger than most other products, which means it is less likely to tear or become damaged in storms or other difficult conditions. Pricing of this product is in the middle ground compared to other products.

When selecting any type of underlayment, your roofing technician considers numerous factors, including where you live, budget, and the type of roofing material being placed. In some situations, the roofing material manufacturer may recommend a specific type of roofing underlayment. Other times, it’s about the location of the home.

Different Underlayment for Different Climates

Underlayment may be selected based on the weather conditions where you live as well. All underlayment has the same goals of providing moisture and damage protection. Yet, some work better in different environments.

Traditional Asphalt Underlayment: There is no way to make this completely weather-proofed, which is why it is typically not used in wet climates. Also, asphalt stiffens when temperatures are low, which can lead to tearing or cracking in some situations. This can lead to an early breakdown of the underlayment.

Synthetic Underlayment: This type of underlayment tends to be a better choice in areas where snow and cold temperatures are common. That’s because it does not become brittle in low temperatures and remains pliable, which means it can bend and move with ice rather than snap.

Ice and Water Shielding: Look for an underlayment that offers ice and water shielding as this can improve the flexibility and durability of the synthetic underlayment used while also providing better adhesion to the roof deck even in difficult climates.

Peel and Stick Underlayment: It is common for some to seek out peel and stick underlayment, which is just what it sounds like. Though more expensive, it tends to provide the highest level of moisture protection that can damage the roof or create mold. Because of its extreme adhesive ability, it tends to be the go-to option in situations where extreme weather conditions exist.

Work closely with your roofing installer to determine the proper underlayment for your home. Note, though, that investing wisely in the underlayment is going to help protect your home, making a higher quality product a bit of a better choice in many areas.

Always Work with the Best

If it’s time to replace your roof, hire a company that’s dedicated to meeting your needs. AGR roofing and construction has been trusted in the Omaha area for over 20 years for superior workmanship and affordable roofing solutions. Contact us today for an estimate.

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