What You Need to Know About Synthetic Roof Underlayment

What You Need to Know About Synthetic Roof Underlayment

Although the roof is one of the most vital parts of a home, many homeowners often look past it in favor of more visible elements, like the walls, windows, and doors. As long as there’s something sturdy overhead protecting them from the elements, that’s good enough. However, it’s essential to know the different roofing materials and how else they defend your home.

Underlayment roof

For instance, roof underlayment, sometimes referred to as ‘felt paper,’ is the first layer of a roof laid down before installing roof shingles or other roofing materials. It is also the first step in the waterproofing process; without it, your home will be more susceptible to water damage and leaks. Here’s what you need to know about roofing underlayment before calling a Raleigh roofing contractor to work on your home:

This Article Contains

Understanding Roof Underlayment

The most common types of roof underlayment used on homes today are asphalt-saturated felt and non-bitumen synthetic underlayment. The first kind is known as tarpaper, and it is older and cheaper while demonstrating water-resistant capabilities. On the other hand, synthetic underlayment is more expensive but is much more stable, sturdy, and resistant to water and tearing.

Since the early aughts, synthetic roof underlayment has been the norm, with most woven or spun from polyethylene or polypropylene. The ingredients of the two are similar, and the manufacturing process and thickness of each underlayment type can be further refined to create different qualities, like walkability and exposure time. You can also compare synthetic underlayment by weight, similar to comparing felt. Synthetics are rated by grams-per-square-meter or GSM rather than pounds-per-100-square-foot. 

Applying roof underlayment is the first part of waterproofing your roof, protecting it from water damage and extensive leaks. It was initially laid to prevent the sap from the wood underneath the roof from leaking through, which could cause the asphalt shingles to deteriorate faster than expected. However, adding a sturdy underlayment can protect all kinds of shingles, especially in hot climates where shingles would have otherwise melted into the wood. 

What is Roofing Felt?

Roofing felt is a polyester or fiberglass fleece soaked in a waterproofing agent to shield the home from moisture and water damage. It is typically available in two thicknesses: 15 pounds and 30 pounds. These numbers reference how much 100-square feet of paper weighed in the first days it was used. However, the actual weight-per-square foot nowadays is much lighter than what’s on the label, although the 15 pound and 30-pound identifiers remained. Roofing felt is often available in 36-inch wide rolls.

Choosing Between Traditional and Synthetic Roof Underlayment

Your roof will always need underlayment to protect your home effectively. You can choose between traditional or organic felt and synthetic felt.

Traditional felt is the first iteration of underlayment and was the go-to for roofing experts before the arrival of synthetic felt. This type of felt is readily available, easy to install, and affordable. On the other hand, synthetic underlayment is a newer entry into the market but offers many more advantages than its traditional counterpart. For instance, it is more water-resistant and lasts longer against ultraviolet light, making it more durable.

The Price Difference Between Synthetic and Traditional Roof Underlayment

Synthetic roof underlayment pricing is based on its weight and performance. Heavier products are usually more expensive because they boast more top-performing qualities, like better durability, longer exposure times, and improved waklability. Thinner synthetics are priced similarly to a high-quality 15 pound felt, but they are still more expensive than cheaper traditional felt.

Thicker synthetics are 30 to 40 percent more expensive than thinner products, but the price difference is ultimately worth it. Going for too thin felt will put your home at risk for water damage since there is less material protecting it. Additionally, thinner products are more prone to puncture holes, tear-outs, and other kinds of damage from imperfections on the decking surface.

The Benefits of Synthetic Underlayment

Synthetic underlayment is not only water-resistant, but it offers more protection from the elements due to its components. This material is often made from durable polymers, making it stronger and longer-lasting. 

Synthetic underlayment is so sturdy that it takes a lot of external force to get it to tear. That means there is less risk of destroying or damaging your underlayment when walking on it while withstanding UV or moisture exposure for long periods, reducing the need to replace or repair it every so often. They provide better protection from heat and everyday wear, offering more heavy-duty defense than traditional underlayment.

Additionally, synthetic underlayment is lightweight. It can even be up to four times lighter than felt, which means you’ll get more material in a roll. A Raleigh roofing contractor will have an easier time installing since they don’t have to make as many trips between the ground and the roof to retrieve the rolls for installation. They’re also safer to install because they usually come with a slip-resistant surface. Its plastic materials are resistant to mold growth, which can be a dangerous health hazard when left unchecked.

The Disadvantages of Synthetic Underlayment

The main disadvantage of synthetic roof underlayment is its cost. Although most synthetic underlayments are competitively priced, they are significantly more expensive than felt. However, despite the higher upfront investment, you’ll be purchasing higher quality roofing materials that will last you much longer and save you from spending on repairs and replacements. Buying synthetic underlayment also sufficiently protects your home from heat, moisture, and UV exposure, giving you peace of mind.


Synthetic roof underlayment can transform your roof and vastly improve how it protects your home. By working with Raleigh roofers, you can find a trusted, reliable synthetic underlayment material that will effectively protect your home and have the best contractors to install them for you.

Southern Premier Roofing is a Raleigh roofing company specializing in roofing, siding, and gutter services, like installation and repairs in several areas, Fayetteville, Hope Mills, Charlotte, and Boise. We provide honest and fair pricing along with outstanding project results, ensuring we do the job the right way and to our customers’ satisfaction. Call us today for a quote!

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