Should I Use Synthetic Or Felt Underlayment For My Roof?

Posted on: 10 August 2022


Shingles are your first line of defense against rain, snow, and hail. However, another line of defense that is important to your roof is underlayment. This is a material that plays a vital role in protecting your roof from moisture damage. Two main types of underlayment you can choose from are synthetic and felt.


Felt is the original type of material that was used for underlayment. It is created with a combination of fiberglass and asphalt. While there are newer types of underlayment that exist, felt underlayment is sometimes still used because it is more affordable. However, you will want to choose the thicker type of that is more resistant to tearing and adverse weather. 


While the material that felt underlayment is made from is less expensive, the installation of a felt underlayment can be more difficult. This is because the felt underlayment is heavier and is more difficult for roofers to carry up a ladder. The slippery surface of felt also makes it much more difficult to install.

The rolls for a felt underlayment also do not have as much material per roll. Therefore, it will take more trips before the underlayment can be fully installed.


Synthetic underlayment is often chosen over felt because it is more resistant to tearing. An underlayment can not only tear due to high winds but can also tear during the installation process.

The shingles for a synthetic underlayment are able to lay flatter during a rainstorm because felt underlayments are able to absorb moisture and swell. This prevents the shingles from laying perfectly flat. Synthetic underlayments are also often chosen because they are very water-resistant. They are made of polymers that are meant to last a long time.

However, it's important to know the characteristics of the specific types of synthetic underlayments when you are having a new roof installed because the underlayments are not standardized. 


One of the advantages of synthetic underlayments is that they are durable enough that they can support foot traffic and are less likely to become damaged in the process. This allows the contractor to easily install the roof without accidentally damaging it. Synthetic underlayment is also a safer material to walk on because it is non-skid. You're more likely to slip and fall with felt underlayment.

Even though synthetic underlayment is more expensive than felt, it is not overwhelmingly more expensive. Therefore, it's a good idea to focus on the advantages of synthetic felt when making your decision.

For more information, contact a roof installation professional near you.