Trends in Roofing Underlayment

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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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  1. Norm

    Installation instructions for GAF’s FeltBuster synthetic underlayment indicate to “install without wrinkles”. The obvious reason why wrinkles must be eliminated is to avoid telegraphing through to the asphalt shingles above.
    But do wrinkles in synthetic underlayments cause other problems? It seems wrinkles could trap water and create hot spots, but I haven’t found any studies or GAF documents which mention this.

    • Jeff Avitabile

      Thank you for your comment Norm. We haven’t seen wrinkling or underlayment that may not be completely flat causing the situations that you mentioned, to date, in research. Appreciate the comment/question.

  2. Ryan J.

    A GAF-Certified contractor re-roofed my home last fall. Before the work began, he indicated he would tear off all roofing materials to the wood deck. But for some reason, his crew only removed the shingles, leaving the 15-year old black felt underlayment in place with a new layer of FeltBuster then placed over it. The work crew managed to keep the underlayment undisturbed by prying up each shingle with pitchforks. That selective removal with pitchforks probably took much longer than a complete tear-off using proper removal tools would have. I can only assume they didn’t remove the old underlayment because they didn’t want to take the extra time to replace any of the wood boards that may have been damaged or deteriorated. The contractor dismissed my concerns about the partial tear-off and when I brought it up a second time, he derisively laughed and indicated I didn’t have to “rehash” the issue.
    In any case, what is the possible impact to the performance of the new GAF products (FeltBuster and shingles) that were installed when there are two layers of underlayment in place (the first layer being black felt underlayment that is 15 years of old and the top layer being new FeltBuster synthetic underlayment)?

    • Jeff Avitabile

      Hello Ryan, thank you for stopping by and your question. Please give our technical team a call at 1-800-ROOF-411 to discuss you particular situation and the details of the installation. Thank you again for visiting.

  3. John

    I’m in the middle of having my new GAF HDZ roof installed. I wish they would have covered stuff in the attic before demolition of the old roof, now I have to figure out beat way to remove the debris from the attic. It’s in the insulation too. Any suggestions would be appreciated.

    • Jeff Avitabile

      Hi John
      Thank you for dropping by the blog. Please give our technical team a call at 1-800-Roof-411. They will be happy to try and provide some guidance on your question. Thank you

  4. Pam

    I had a re-roof done on my home last May. I used FeltBuster as the underlayment for a 37sq full hip style roof usingTimberline HD shingles. After dry-in (which passed inspection) but before the shingles were installed three weeks later, we experienced significant leaking. It was explained that this was due to the local code requiring the use of metal tabs instead of the plastic caps indicated in the installation instructions provided by GAF. The shingles were installed later but there wasn’t anything done to the underlayment as presumably the code issue superseded any correction available. This was approximately 8 months ago and I find there may be additional leaking during windy rain storms. Also, the vents that were installed are half of the “size” of what we were expecting. Our roof/attic floor area is approximately 2600sq ft. and we have 3 4’ off ridge vents (and continuous soffiit venting). Is this adequate ventilation? If not, how can I increase ventilation? I live on the south east coast of Florida.

    • Jeff Avitabile

      Hi Pam,
      You’re correct in that local building code or requirements will always take precedent over manufacturer’s installation instruction. As you can imagine, Florida (and other state/regional groups) have specific requirements. This can often vary across the country. If you’re seeing leaking, you may want to have a contractor take a look at your roof system to identify a potential cause during heavy wind storms. In terms of your attic ventilation, for attic floor space of 2,600 square feet, following the 1:300 rule for balanced ventilation, you would want to have 624 sq. in. of exhaust ventilation and 624 sq. in. of intake ventilation. Most plastic ridge vents provide 18 sq. in. of exhaust ventilation per lineal foot. So, you would want to have a minimum of 34-35 ft. of ridge vent installed. You also need to ensure the continuous soffit vents are completely “open” and not clogged or covered by your attic floor insulation (a common issue). Finally, you may want to consider a power roof ventilator, if you’re looking for enhanced ventilation. These powered units help exhaust large volumes of heat and moisture from your attic. Thank you for dropping by.

  5. Matt

    Jeff, many thanks. Now I understand why another county wanted a ma underlayment put down first, then the sa waterproof layer. Many folks including myself didn’t understand the logic. Now I do. By putting down a ma layer first, then the waterproof sa layer, the roof system would be removeable down the road with no damage to the decking. Under the shingles would be a secondary waterproof layer that could seal the nail holes. It’s just not glued down. I would much rather pay for an ma layer now, than redeck in 20 years.

    • Jeff Avitabile

      Welcome Matt. Excellent point, as many counties in Florida do require a mechanically attached underlayment be used as a “anchor” sheet before applying a self-adhering underlayment. Best of luck with your project and thanks for stopping by our GAF Blog.

  6. Matt

    Close to signing a contract. Roofer A will be putting shingles directly on peel and stick. This is our forever home. Roofer B is concerned that when I go to re-roof, the shingles will have melted into the peel and stick. Removal of shingles will result in the peel and stick being ruined and probably the decking as well. So, Roofer B is suggesting a layer of felt over the top of the peel and stick so that the shingles can be removed for the next roof and the peel and stick remain intact. This is hurricane country and it’s hot.
    1. So, in 20 years, does the peel and stick have to come off? If so the cost to re-deck will be huge.
    2. If the peel and stick can stay on 30 years, why wouldn’t I use a layer of felt between the shingles and the peel and stick?

    • Jeff Avitabile

      Hi Matt,
      Thank for your question. We would always suggest checking with local building code as per their requirement for re-using underlayments when re-roofing. As you stated, attempting to remove peel and stick from the roof deck in just a few years can be virtually impossible, let alone in 30 years, and typically requires replacement of the plywood deck. “Good roofing practice” would suggest replacement of any underlayments when re-roofing, but again, given the difficulty and cost of trying to remove peel and stick underlayment from the entire wood roof deck, there’s reason to look for acceptable alternatives. The suggestion that a layer of felt or synthetic mechanically attached underlayment to serve as a sacrificial layer between the shingles and peel and stick is a good one. However, again, I would recommend checking with your local building code to ensure they allow reusing of underlayments down the road. Other than that, there’s really not a downside of using that sacrificial layer of felt, as suggested by the roofer. Thanks again for stopping by.

    • Jeff Avitabile

      Hello Patrick,
      Unfortunately, GAF doesn’t currently offer a peel and stick underlayment for use under Tile. In terms of peel and stick, we do have options for asphalt shingles, metal and synthetic roof coverings. Tile will hopefully be something in the near future. Thank you for your question.

  7. Dan pepi

    My roofer is in the process of doing m roof with the GAF products and left yesterday with part of the roof with just the GAF underpayment exposed.Raining heavy today, will that cause a problem when the shingles are applied.

    • Jeff Avitabile

      Hi Dan,
      Typically, the roofer will allow the system to dry out before shingling over. Please give our technical team a call at 1-800-ROOF-411 to discuss your specific job/situation. Thank you for dropping by.

  8. Rickey

    We are planning to replace our roof using your GAF elite Master Contractor and get your 50 Year Gold Policy. We currently have Gutter Helmit (gutter gard). Does reinstalling the Gutter Helment have negative impact on our roof performance or an issue with our Warranty?

    • Jeff Avitabile

      Hi Rickey, thank you for dropping by and for choosing GAF. Typically, the limited warranty wouldn’t be affected. That being said, I would recommend giving our technical team a call at 1-800-Roof-411 for specific details on warranty coverage. Thank you again.

  9. Ken

    Hello Jeff – I don’t think my questions should be that complicated for you, but I have spent a long time trying to determine a well thought-out and best practice (re) roof assembly.

    My questions for you pertain to the appropriateness of interwoven Synthetic Roofing Underlayment & poly woven drain screen type strips providing some limited separation (see below).

    THE FACTS: Location – Pacific Northwest (read WET); – Existing Roof Slope: 12 in 12 (45 degrees).
    Appropriate planks and jacks will therefore be used for roofing install with proper fall restraint equipment ; Exposure – open and without trees around – ridge oriented North – South; – The Building – existing non-residential accessory w/o heat (home shop); – Proposed New Roofing – Number 1 16″ taper sawn western red cedar shakes; – Existing Roof/Deck & Sheathing – spaced/skip 1 X 6 boards; Ventilation – continuous eave & ridge – also (now) with open vented attic w/o Insulation at this time – appropriate provisions have been made to allow for Code compliant roof venting above thermal insulation in the vaulted roof assembly – should this be proposed at a later date.

    PROPOSED ROOF ASSEMBLY: As “normal” 🙂 , given all the above noted details above, “but” with/proposed – interwoven high perm rated Synthetic Roofing Underlayment …and – 2″ strips of 3/8″ poly woven “drain screen” type membrane (Home Slicker type). Poly woven strips to be placed 1″ – 2″ above the “line of exposure” – and placed on the “to the weather” side – e.g. – 6″ to 7″ up from bottom/butt of shakes – 18″ shakes with 5″ exposure. With woven poly strips oriented parallel to ridge (see more info below).

    I am also considering placing 2″ X 1/2″ (…or 3/8″ thick…) P.T. plywood “rain-screen strips” placed over/on the existing roof skip-sheathing and “below” the proposed interwoven underlayment. I am not concerned with potential “ponding” as roof slope is a steep 45 degrees. Ply P.T. strips placed at the appropriate on-center locations & perpendicular to the roofing & parallel to the ridge.

    Shakes would be “firmly hand-nailed”, such that the final separation, from the top of the shake to underside of the shake in the next course above would be around 3/16″. Therefore, about a 50% compression of the poly woven strips.

    BTW, I am clearly an obsessive and retired journeyman carpenter followed by a 20 year career as a government Building Official. P.T. Cedar Shakes are placed on my house, but are far too expensive for us on my shop.

    THE QUESTIONS FOR YOU: – If you are willing, please provide your comments on the proposed underlayment, the 2″ plastic/spun breather strips and the proposed plywood “rain-screen strips” – to be carefully aligned over existing skip-sheathing so shake nailing would be precisely placed in the center of the new P.T. strips. I am happy to draw this in cross-section and send it to you 🙂

    The Building Code here requires the application of a minimum 3/8″ rain-screen, so the lumber yards here always have a good supply of 1 1/2″ & 2″ P.T. plywood strips, and spun poly membrane.

    Just seems like a goody method of allowing for more air below and around the shingles (e.g. 2″ shake contact VS 5.5″ contact for/on the boards). Presumably therefore allowing for a longer service life of the cedar shake roofing – my main goal. Sadly, with all my many hours of study, I am simply unable to determine the suitability of this assembly. Thanks in advance! Ken Jackson

    • Jeff Avitabile

      Hello Ken, thank you for dropping by and for your question. As you mentioned, it’s a pretty specific installation detail/system. I’ve shared your question with some of our technical and building science folks within GAF to get their thoughts and feedback. They would recommend contacting the Cedar Shake & Shingle Bureau at Given your installation is specific to wood roofing materials, they would be your best source for technical information and/or recommended system installation. In addition, the NRCA (National Roof Contractors Association) is another good source of information for your questions. They also have technical resources dedicated to wood roofing systems, as well. I hope this information helps point you in the right direction. Best of luck with your new roof system and thank you again for dropping by our blog.

  10. Donald Cummings

    A local GAF certified roofer I am considering using, is stating that he will not use a peel and stick underlayment on my 5 in 12 pitch plywood sheathed roof. Stating he will use felt buster, because peel and stick underlayment causes moisture problems. that if I want peel and stick he will do it, but will not use ridge vents and instead will install four power ventilator fans. I am in Hurricane territory of the Florida Suncoast , Clearwater Florida.
    I am interested in having as much protection as possible should a shingle be damaged during a storm. Do I get that with Felt Buster? If not what do you suggest be used as underlayment?

    • Jeff Avitabile

      Hi Donald, utilizing full deck coverage of peel and stick leak barrier would provide maximum protection, as you desire. Your contractor brings up an excellent point in that type of system needs proper attic ventilation to reduce any issues of moisture build-up. There’s really no issue with utilizing power ventilators, instead of ridge vents. The key is ensuring there is a proper amount of balanced ventilation (intake and exhaust) regardless of the products used to provide. I hope that helps! Thank you for stopping by and for the question.

    • Jeff Avitabile

      Hi Jeremy, please give our technical team a call at 1-800-ROOF-411 for specifics on warranty and warranty coverage. They would be glad to help.

  11. Mike H


    Thank you for the quick response. Through Lowe’s, a GAF certified contract is installing a TimberTex HD Ultra roof. While the Lowes quote calls for removing the “existing roofing system” the contractor says it is best to leave the felt on and it is not part of the roofing system. What is correct?

    • Jeff Avitabile

      Hi Mike,
      We recommend removing the existing roofing system including shingles, underlayments etc. and installing a new roofing system. For particulars on your job, please give the technical team a call. They can discuss a bit further in detail. Thanks again for your question.

    • Jeff Avitabile

      Hi Mike,
      We would recommend removing any existing roofing materials and underlayments if possible. If you have more specific questions on installation, please give our technical team a call at 1-800-ROOF-411. Thanks for dropping by.

  12. Fred Cunningham

    Hi Jeff,
    I’m in the process of receiving roofing quotes from GAF Master Elite contractors, and I’m getting conflicting recommendations. Contractor #1 is quoting “peel n’ stick” on the entire roof, while Contractor #2 is recommending synthetic underlayment on the field and “peel n’ stick” on the edge and valleys. I ‘m wondering what GAF recommends.

    • Jeff Avitabile

      Hi Fred,
      Either system would be approved by GAF. Typically, contractors or homeowners would go with full-deck peel and stick leak barrier if required by local building code or in areas of severe weather conditions (i.e. those areas prone to ice damming, harsh winter climates, or hurricanes etc.). Some contractors may still select that type of installation even outside of those severe weather locations if for example the roof is a complex design or has many “cuts” or intersecting planes etc. That being said, the most common system in many areas of the country is to have peel and stick at the the most vulnerable areas of the roof (i.e. eaves, valleys, around penetrations etc) along with fastened underlayment (synthetic or felt) on the remainder of the roof. So, in short, either system is totally fine and would be approved by GAF, but please consider the above local considerations when making your decision. Thank you for stopping by and for choosing GAF products for your new roof.

  13. manuel pedroza

    hi Jeff, i already install feltbuster 10 days ago, but the shingles arrive to mi house until monday, it’s that a problem or i have more time to install the shingles once i install the felbuster

    • Jeff Avitabile

      Hi Manuel,
      Thank you for stopping by and for your question. The FeltBuster product has a UV resistance rating for up to 90 days, so there should be no issue. Please keep in mind that the product, like any other synthetic roofing underlayment, is not technically a “temporary roof”. It’s intention is to serve as a secondary water-shedding layer under your shingles. So, if you’re expected rain before your shingles are installed, please tarp or cover the roof to avoid potential issues. Other than that, the product is designed to avoid UV degradation up to 90 days. Thanks again for your question.

  14. Steve

    Hello! Is there any third party documentation that supports the use of 30# felt on a 7/12 or steeper pitched roof? Thanks!

    • Jeff Avitabile

      Hi Steve, Thanks for dropping by. I’m not personally aware of 3rd party documentation regarding this particular topic. Although GAF does not offer a specific #30 asphalt felt product, these particular felts have been used for decades to roof on all types of roof pitches.

  15. Josh

    I got an estimate for a project that includes Tiger Paw. I’m concerned, though, that Tiger Paw is not as breathable as felt. We live in a very humid place. Shouldn’t I be concerned about the relative non-breathability of Tiger Paw v. Felt?

    • Jeff Avitabile

      Hello Josh,
      GAF recommends proper attic ventilation (balanced between intake and exhaust) be installed to help manage moisture in the attic and roofing system. That’s regardless of what type of underlayment is installed. I would suggest having your contractor review and ensure that is present on your property. More specifically, Tiger Paw is classified as a non-breathable underlayment, so if you’re looking for an optimal choice for managing excess moisture, Deck-Armor, a breathable UDL, may be a good solution for you. Again, proper attic ventilation should always be the starting point to these situations. Thank you for your question.

  16. 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?

    • Jeff Avitabile

      Hello, we do allow Tiger Paw or Deck-Armor to be used on metal roofing systems. I would also recommend verifying there is proper, effective attic ventilation installed in addition to verifying what may be driving this excess moisture. You may want to contact our technical services hotline at 1-800-ROOF-411 for further information on this specific situation. Thank you for dropping by.

  17. 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.

    • 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.

  18. 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?

  19. 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.

    • 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!

    • 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.

  20. 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!

  21. 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.

  22. 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.

    • 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.

    • 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

      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.

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