Synthetic vs. Felt Roof Underlayment

Published on Friday February 18, 2022

A photo of synthetic roof underlayment vs felt

When homeowners consider a new roof, the proper roof underlayment isn’t exactly the first thing that comes to mind. It’s more common to dissect the differences between shingles or metal roofing than to compare synthetic roof underlayment vs. felt.

That being said, it’s important to understand the differences between roof felt paper vs. synthetic underlayment when you’re upgrading your home’s roof. A new roof is a substantial investment and you want to make sure the job is done right. Underlayment can make a big difference in extending the lifespan of your roof, so you want to be sure you consider it and go with the best option for your roofing type, materials, and budget.

What Is Roofing Underlayment?

You can’t accurately compare synthetic roof underlayment vs. felt if you don’t understand what roofing underlayment is in the first place. The roofing underlayment is what’s installed between the shingles and roof deck (that is, the plywood or OSB layer). Roofing underlayment is typically installed directly on the roof deck and is designed to provide extra protection from moisture and weather.

Essentially, roofing underlayment is an extra sheet of protection between your roof and the elements. It helps keep your roof safe from rain, snow, and wind, thereby keeping your home safer against leaks and water damage, making it safer and more energy-efficient.

Types of Roofing Underlayment

When it comes to roofing underlayment, there are two main types to consider: roof felt paper vs. synthetic underlayment. Both of these have clear pros and cons so you want to be sure to compare them before choosing one or the other for your roof installation.

Additionally, one may be better than the other depending on the type of roofing materials you’ve chosen for your home, your roof design, your budget, your geographical location, and what roofing contractor you work with. Consult with your roofing contractor before making your ultimate decision. This will help ensure you get the best project possible in the end.

Synthetic Roof Underlayment vs. Felt Underlayment

What is Felt Roofing Underlayment?

Felt underlayment is made from saturated paper or fiberglass mat with asphalt. It’s one of the oldest types of roofing underlayment and comes in different thicknesses and strength levels. Usually, the thicker felt roofing underlayment is stronger and less prone to ripping or tearing, but it is also heavier and more expensive.

Here are some pros and cons to consider:

Pros

Felt underlayment is incredibly budget-friendly, which is usually seen as its main advantage. It costs less than most synthetic underlayment so homeowners looking for the most budget-conscious choice often go with felt.

Here’s a condensed list of felt roofing underlayment advantages:

Low cost
Breathability
Easy installation

Cons

While their low cost is an advantage, felt roofing underlayment comes with plenty of cons. The main disadvantage of felt underlayment is that it cannot be exposed to the elements for more than a few hours without drying out and wearing down, greatly reducing its effectiveness with moisture protection.

Here are the main disadvantages of felt underlayment:

Prone to tearing (especially during installation and when exposed to high winds)
Absorbs water and can wrinkle and buckle easily (especially if the installation takes too long)
Felt underlayment weights more than synthetic, making the installation more difficult
Slippery surface, making installation more difficult
Does not hold up well to boot traffic

What Is Synthetic Underlayment?

Synthetic roofing underlayment is usually made from long-lasting polymers to help provide reliability and longevity. WIth enhanced moisture resistance and durability against the elements, this type of roofing underlayment is becoming increasingly popular with roofing contractors and homeowners. When installed correctly, it offers the best protection from the elements when comparing roof felt paper vs. synthetic underlayment.

It’s important to note that the materials used for synthetic roofing underlayment are not standardized. This means manufacturers can make theirs differently, which means they all might perform at varying levels. Do your research and always consult with a trusted professional before installing roofing underlayment for your home. This will help ensure you get the most value from your investment.

Here are some synthetic roofing underlayment pros and cons to consider:

Pros

The main advantage of synthetic roofing underlayment is its easy installation process and toughness. While felt is easy to rip and tear, synthetic roofing underlayment is far more reliable. It’s tough, water-resistance, safe to use, and quick to install. Here are some of the main advantages to consider:

Easy installation
Water-repelling
Tough, durable construction with high tear resistance
Durability against UV rays, moisture, and winds (so it can withstand exposure far longer than felt underlayment can)
Higher heat tolerance
Holds up to boot traffic, making the roofing installation much easier
Lightweight

Cons

While synthetic roofing underlayment certainly has a long list of pros, you have to consider the cons as well. Here are some of synthetic roofing underlayment’s main disadvantages for you to investigate so you know what you’re getting into:

When compared to felt, synthetic roofing underlayment is pretty pricey
Little to no standardization across manufacturers

The Right Underlayment for Your Roof

So, what’s the best roofing underlayment for you, synthetic or felt? If you’re looking for the most budget-friendly option, then felt underlayment is the way to go. However, if you want the most durable, reliable choice, then you will most likely want to choose synthetic.
Consult with a roofing professional to learn the best underlayment for your chosen roofing materials. If you have any questions or would like a project estimate, don’t hesitate to reach out to Long Roofing. If you’re looking for high-quality roof repair, the experts at Long Home Products can get the job done. Find your closest Long Home Products location today.