Trends in Roofing Underlayment

Over the last 10-15 years, the roofing underlayment market has undergone a major shift from traditional asphalt felts to synthetic underlayments. In the early 2000s, there were a handful of synthetic underlayment products all trying to wrestle a sliver of the market away from asphalt felts. Today, there is an endless array of synthetic underlayment brands available, with more coming every day. This exponential growth can be attributed to the increasing number of contractors who value the enhanced features and performance of synthetic underlayments. In addition to features, pricing is a major driver as the gap between synthetics and felt continues to shrink, helping to loosen felt’s grip on the market.

One of the most important features of today’s synthetic underlayments is enhanced walkability in both wet and dry conditions. In fact, a 2014 GAF survey of Master Elite® Contractors found that the most valued installation attribute of an underlayment by far is walkability/safety, followed by strength/tear-resistance. Typically made of polypropylene, synthetic underlayments are virtually untearable and do not absorb moisture. This helps to avoid wrinkling and telegraphing, which can take away from the finished look of the roof. These features are all major factors for the migration away from felt and toward synthetics.

GAF has been a leader in the synthetic underlayment market, beginning first in 2006 with Deck-Armor™ Premium Breathable Roof Deck Protection, with its unique breathable technology, and later in 2011 with Tiger Paw™ Roof Deck Protection, one of the most popular synthetic products on the market. Now, in order to provide a superior, cost-competitive option for contractors who still haven’t made the switch from asphalt felts, GAF has launched FeltBuster® High-Traction Synthetic Roofing Felt, now available everywhere.

This lightweight, 10-square, 48″-wide roll is designed for use with asphalt shingles. FeltBuster® High-Traction Roofing Felt combines tough synthetic construction with a special spunbound walking surface. This surface helps provide increased traction compared to typical asphalt felts. Its medium-gray surface is cooler to work on than either traditional black felts or the leading low-cost synthetic felt replacement (which is also black). As with all of GAF’s underlayments, FeltBuster® High-Traction Roofing Felt is part of the GAF Lifetime Roofing System and is covered by a Lifetime* ltd. warranty when installed as part of that system.

So, GAF’s lineup of synthetic underlayments now includes FeltBuster® (good), Tiger Paw™ (better), and Deck-Armor™ (best).

Learn more about GAF’s new FeltBuster® High-Traction Synthetic Roofing Felt. 

*See GAF Shingle & Accessory Ltd. Warranty for complete coverage and restrictions. The word “Lifetime” means as long as the original individual owner(s) of a single-family detached residence [or the second owner(s) in certain circumstances] owns the property where the shingles and accessories are installed. For owners/structures not meeting the above criteria, Lifetime coverage is not applicable. Lifetime ltd. warranty on accessories requires the use of at least three qualifying GAF accessories and the use of Lifetime Shingles.

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    • Jeff Avitabile

      Hi Don, thanks for dropping by and for your question on FeltBuster.

      FeltBuster has been successfully tested to the ASTM D4869 water shower component which helps to ensure the product sheds water properly. So, in short, FeltBuster is expected to perform very similarly to Deck-Armor and Tiger Paw in terms of its water-shedding capability.

      Another important thing to note. GAF asks that folks use plastic cap nails or plastic cap staples when fastening our synthetic underlayment products to help maintain a water-shedding installation. Unlike waterproof peel and stick leak barriers, such as Weather Watch, synthetic underlayments are not waterproof since there are no self-sealing capabilities in these products to help seal around the fasteners.

      Thank you again for checking our our blog.

    • Jeff Avitabile

      Hi Joe, thanks for your question. Many synthetic underlayment products are very competitive (per square basis) with #15/30 asphalt felts. There are more premium priced synthetics that offer additional features such as breathability or long term UV exposure etc. These premium products still remain more expensive than typical felts. Please keep in mind, pricing varies by market.

    • Jeff Avitabile

      Hello Bill, thank you for dropping by and for posting your question. Traditional #15/#30 asphalt felts are water-resistant or water-shedding products. Since they are not peel and stick and do not have the capability to seal around fasteners or at laps, they technically shouldn’t be classified as waterproof.

  1. Tim

    How important is deck armor’s breathability vs felt buster? My roof underneath is made up of 3/4″ boards and is well ventilated. I don’t want to pay more than I have to, but $200 savings on a job that could be worse with trapped moisture doesn’t seem worth it. Up here in the northeast many roofs have no paper at all once you get past the bottom 3 feet. I wouldn’t think the shingles themselves are breathable.

    • Jeff Avitabile

      Hi Tim and thanks for stopping by our blog. Our position over the years has been to utilize a breathable roofing underlayment along with proper attic ventilation (consisting of balanced intake and exhaust) as the “best choice” for managing moisture in the roofing system. That being said, the majority of the market including GAF offers non-breathable synthetic underlayments. In fact, they are the most common type of synthetic underlayment on the market today. Many contractors and building science experts believe that a non-breathable product adequately serves the purpose. GAF’s non-breathable synthetic options such as Tiger Paw and FeltBuster offer options for these specific folks, but we do maintain and highlight in our installation instructions that proper attic ventilation is critical, especially when non-breathable underlayments are used. Recently, GAF conducted a two year joint research project with Oak Ridge National Laboratories in which the effectiveness of breathable underlayments, in this case Deck-Armor, was measured against non-breathable underlayments. Sensors captured thousands of data points over the two years and measured moisture content in the roofing system as well as temperature. The study found that the system with Deck-Armor had 11% less moisture in the system during the winter months and up to 30% less moisture in the system during the summer months. Also, the underlayment temperature was up to 10 degrees cooler overall. I hope this gives you some background on why we promote Deck-Armor as a best choice option. Again, non-breathables are OK, but proper attic ventilation is especially critical in this case. Thank you again for your question.

  2. Darryl Dyck

    Did the GAF joint research project with Oak Ridge National Labrotories which tested the effectiveness of breathable underlayments include a traditional felt product? If so how did it compare to Deck Armor and the non-breathable underlayments.

    • Jeff Avitabile

      Hi Darryl, thanks for dropping by and for your question. The first phase of the study with ORNL included non-breathable synthetics and breathable synthetics (such as Deck-Armor), as we were particularly interested in learning the performance differences/advantages of these two product types. Since conventional felt underlayments are breathable by nature and the industry with the industry moving more and more towards synthetics because of strength, price, walkability etc., we focused this phase of the study on the synthetic products. Thank you again for your question.

  3. Zachary

    My roofing contractor installed Felt Buster in lieu of Deck Armor as contracted. We specifically were interested in Deck Armor because it attic wasn’t properly ventilated (ventilation has between improved as part of the product). In terms of long term impact to the roof assuming the attic is now appropriately ventilated, what are the potential risks? Higher probability of failure, damage to plywood, etc.

    • Jeff Avitabile

      Hello Zachary, thanks for dropping by and for your question. As you may know, GAF highly recommends that a properly balanced attic ventilation consisting of both intake and exhaust ventilation be used on virtually all asphalt shingle roof systems, irregardless of underlayment. Based on findings from the joint Oak Ridge National Labs/GAF study, those systems with a properly balanced attic ventilation system were able to manage moisture and control temperature in virtually all attic/roof assemblies, including those assemblies with breathable and non-breathable underlayments. Thus, based on these findings, it is highly likely that a properly installed attic ventilation system will help to reduce the risk of system deterioration/damage. Keep in mind, every home/attic is different in terms of construction, moisture load, temperature load etc. Thank you again for your question!

    • Jeff Avitabile

      Hi Al, thanks for your question and for visiting the GAF blog. We ask that FeltBuster only be installed with asphalt shingles. Our other synthetic underlayment products, such as Deck-Armor and Tiger Paw, can be used under alternate roof coverings such as tile, slate or metal. Thanks again for your question.

    • Jeff Avitabile

      Hello Kristian, thank you for your question. Although from a physical properties/performance perspective, our synthetic underlayment products would probably work in this application, unfortunately we do not offer an approved product for sidewall applications, including stucco etc. Thank you again for stopping by and for the question. We appreciate it!

  4. Charlie

    My roofing contractor is GAF certified. He is putting on Armor Shield II with 7/16 OSB sheathing over my 1×10 deck (city codes require solid decking). Attic turbines will be installed. He has suggest Feltbuster synthetic decking. I was looking at Tiger Paw and Deck Armor, but thinking maybe Deck Armor might be overkill on this roof. What are the advantages in my situation of Tiger Paw over Feltbuster on a lifetime roof? Thanks

    • Jeff Avitabile

      Hello Charlie, thanks for your question. Both Tiger Paw and FeltBuster will help to provide a durable, high-performance solution for your roof system. They’re both extremely tough products and their synthetic construction will help them last for the life of your roof. One of the key differences between Tiger Paw and FeltBuster to consider is the moisture absorption coating on the back of the product which helps absorb excess moisture on the roof deck. Given that your contractor installs a proper attic ventilation system (intake and exhaust), either underlayment product should meet your system needs. Thank you again for your question.

  5. Chris

    We have gutted an antique home for a deep energy retrofit. Currently, the plank roof sheathing is backed by 8″ of closed cell spray foam. If we use peel/stick over the entire roof, I’m worried about creating a double vapor barrier and rotting out the sheathing. If we use a breathable synthetic felt, we’re still on a hot roof, which I’m sure voids the warranty on the Timberlines we hope to use. Do we need to strap and resheath the roof, or can we get by with the synthetic? What details for a closed cell backed roof will not void the warranty?

    • Jeff Avitabile

      Hello Sofia, we recommend FeltBuster be used as an underlayment only with asphalt shingles. For residential roll roofing products, a product such as GAF Shingle-Mate Fiberglass Reinforced roof deck protection can be used as underlayment. For further details/questions on your particular installation, please give our technical services group a call at 1-800-ROOF-411. Thank you for dropping by and for your question.

  6. Doug Martin

    Jeff: When you reroof an existing roof that has peel and stick already, how do you get the old peel and stick off. Can you put new peel and stick waterproof barrier over top of peel and stick? Any info you can provide is appreciated.

    • Jeff Avitabile

      Hi Doug, thank you for your question. As you probably are aware, it can be quite difficult to remove existing peel and stick. While GAF strongly recommends the removal of the existing self-adhered leak barrier when re-roofing, if that’s not possible, you may want to to either replace the roof deck in those specific areas, or attempt to “feather in” the new layer by extending the material a minimum of 8” past the existing material. Please note, that not all building materials are designed to be in contact with each other due material compatibility issues. With that in mind, GAF is not responsible for any damage caused by incompatibility with any leak barrier not manufactured by GAF. Thanks for dropping by and for the great question.

  7. Rodney Bogle

    I have switched all of my installs to the GAF felt buster. I just found out that I am not supposed to use on metal roofs. I have installed a 16′ standing seam metal roof on a 105 square roof that also has the LP foil on the backside. The decking is holding moisture and buckling my roof. Any suggestions on my next direction. What under layments do you offer that can be used on a metal roof?

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