Synthetic VS. Felt Underlayment – Which Is Better?

"Synthetic VS Felt" across a background of two white doors.
Synthetic VS Felt Underlayment – Do You Know The Difference?

Why Does It Matter?

For anyone reading this, if you are curious to know what goes on under the shingles on your roof, you can find the answers in simple terms here.

This topic matters for homeowners, specifically, though. If you don’t have any knowledge of how the different steps of roof repair work, then you are trusting the roofing company to explain things to you. Hopefully they are honest of forthright at that point.

Plus, in certain circumstances, less-than-honest roofing contractors may try to take advantage of the ignorance of good people who simply don’t have time to learn how a roof works. So, as a solution, we have this easy to read, short blog, that explains everything you need to know, in a timely fashion.

What Is An Underlayment?


Underlayment is a layer of material, laid between the decking of a roof and the roofing material.

Underlayment redirects water, blown back under the shingles during high wind rains. Additionally, it provides a layer between the wooden roof decking and the outside moisture. This helps moisture build up under your shingles, as the water rolls down from under the roofing material, into your gutters. Additionally, this helps against mold and mildew from building up on the wooden decking.

What Is The Difference Between The Two?

Synthetic underlayment vs. felt underlayment. Both have advantages and disadvantages. To understand the advantageous differences, you have to understand the physical differences, first.

Felt Underlayment:

"Felt Underlayment" across a faded picture of a roof under repair, felt exposed. Woodgrain background behind photo.

Felt underlayment is composed of natural materials, like plant fibers or wood cellulose, which is saturated in asphalt to give it water resistance.

It is also less expensive than synthetic underlayment. Plus, it is readily available in most of the U.S.. So, price and supply are definitely in favor of the felt underlayment.

Synthetic Underlayment:

"Synthetic Underlayment" across a roof under repair, synthetic underlay showing. Woodgrain background behind photo.

After a long time of felt underlayment being the primary choice for roof underlayment in the U.S., synthetic underlayment entered the market in the late 20th Century. Since, it has become one of the leading underlayment products on the market.

Synthetic underlayment is composed of a polymer, combined with polyethylene or a polypropylene . Together, they form a much more durable, and effective barrier between the decking and the shingles/metal, than felt underlayment.

So Which Product Is The Better Choice?

Both synthetic, and felt, underlayments have advantages, and disadvantages. As explained above. The deciding factor between the two usually comes down to budget. Because, who wouldn’t want the nicer material on their roof if they understood what it was?

Certain roofing companies only use synthetic underlayment on their roofs. So, by choosing to do business with them, you are choosing to have synthetic underlayment. Which isn’t a bad thing.

The Winner, In Our Book.

"WINNER" across faded picture of victorious hand being raised in a boxing ring, next to defeated opponent. Gray tile background.
We believe synthetic underlay is a necessity in Texas.

If you have the option to choose, and the funds are available, we highly recommend the synthetic underlayment. It has proven itself as a better protector against the elements, especially in an extreme heat environment like Texas summers. For our own roofing company, we don’t use felt underlayments simply to help ensure our works quality, and our customer’s long term satisfaction.

To Be Fair.

We are not saying felt underlayment is never a good idea. In extreme hot, or cold, however, felt does have a higher chance of deteriorating, and allowing moisture into your roof.

Things To Watch Out For.

In regards to underlayment, felt or synthetic, there isn’t a whole lot of things to be cautious of. However, ensuring the few things a homeowner should keep an eye out for, are taken care of, is critical.

Some of the more devious roofing contractors have skipped applying the underlay all together. An attempt at saving the company money, at the expense of the homeowner, usually.

Greed is usually the root of most business related flaws. More commonly seen than simply not installing the underlay, roofing companies will inflate certain costs above their value, including underlay costs.

Don’t Be Afraid, But Don’t Be A Fool.


These instances are few, but enough to justify being savvy, and aware. So, on’t just assume the roof is being installed correctly, know it is. Walk outside while they are putting it on, and see if their is a layer of something that they are putting down before the shingles or metal. If they are just putting shingles or metal directly on wood, that is a big red flag.

If you want to be thorough, ask them to show you a piece of it. It should say “synthetic” directly on the material if you spent the extra money on synthetic underlayment.

Why We Want To Help You.

Our blog’s priority is to keep DFW homeowners informed of their options. Many roofing companies are sales businesses, and keep the customer only as informed as they need to be. We are putting a stop to the homeowner being at this disadvantage.

We have our own roofing company as well, Craven Roofing & Construction, Inc., located here locally in the fort worth area. Our business model is simple. We are a full service, repair service, not a sales business. We inform our customers so that they know there is a company that they can trust.

When you do business with us, we are their to fix the problem, whether it is a menial roof patch, or a full scale replacement. Find a roofing company who’s primary concern is solving your problem, not how much they will make while doing so.

How We Can Help You.

Focusing on repairs first was the principal Craven Roofing was built on. With basic and even major repairs being largely overlooked, we felt the need to step in and be the roof repair service that homeowners deserve.

No problem your roof has is a waste of our time. It is our goal to set the par for roofing companies much higher, and to give homeowners the repair options that they deserve. Not just the ones that make lots of commission for the roofing contractor.

Want to talk to a repairman? Give us a call.

Thank You For Reading!

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