Roofing/Roofing

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Question
I have to bids on my roof. One in going to use GAF deck armor. They other is going to use tar paper. Is one better than a nether. I live in Maine. LONG WINTERS.

Answer
Doug,

Your question did not share what roof covering you intended to have them installed atop the underlayment, not that it is a significant impact but it is part of the situation.  Let's presume for the sake of this discussion, you plan to have an asphalt shingle installed as this is the choice of 80% of homeowners in the US.

The big difference between the 2 products is one being organic (paper felt) and the other synthetic (polypropylene). The asphalt felt (ASTM D 226 Type I) is commonly referred to as a "number 15 felt".  It is a paper mat that is saturated with an asphalt flux, it is reasonably effective as an underlayment to shed water but is not waterproof and if it gets wet (even with dew) after it is installed and prior to shingles being completed, it will wrinkle as it swells being organic. The wrinkles can often be seen under the shingles, which is the main factor behind the invention of synthetic underlayments such as the "Deck Armor".

The Deck Armour is a synthetic (inorganic) underlayment designed not to swell and wrinkle it is gets wet prior to shingle installation. Interestingly, there is a specific test standard (ASTM D 6757)for these types of products, but I am aware of no one who actually promotes testing to that, they test to the same standard so the organic felt (ASTM D 226). My opinion is most manufacturers over-market the value of synthetic underlayments in lieu just sharing the real and honest advantages.

Let me share that both products will work fine.  Likely the Deck Armor is a slight cost add versus the organic felt. The true advantage of the Deck Armor is that if put on correctly will lay flat, shed water (the 2 big things you want) and perform fine under asphalt shingles. If it was my money, I would go for the Deck Armor as it will be a plus for you.  The one reminder I will share for you to ensure you follow through with the installer is, use of the Deck Armor may qualify for an enhance manufacturer's warranty.  Be sure your proposal you sign clearly states they will "install all roofing related product is a manner complaint with the most current published manufacturers' requirements".  Ensure they provide all manufacturer's warranties.  Contractor's often fail to give these to homeowners.  Many of the warranties require you to "register" them within a time period of the roof being installed, so read your warranty carefully to comply with any registration requirements.

Hopefully, this information will be helpful in your roofing adventure.  My last words of advise is read everything completely, do not just take someone's word for things, make sure EVERYTHING is on the contract you sign (all products and application techniques) and that it also does not require final payment until completion and acceptance by you.

Steven Wadding RRC,RRO,CDT

Roofing

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Steven C. Wadding RRC,RRO,CDT

Expertise

General questions in regards to most roof types and situations. As the Technical Services Manager for Polyglass USA, Inc. this would not be a forum to address any issues directly related to a product my employer manufacturers.

Experience

I have been active in the roofing and waterproofing industries for more than 30 years with extensive experience from product installation, product development and consulting. I have been active in the Construction Specifications Institute and Roof Consultants Institute for approximately 20 years. I am a member of ASTM and am a voting member of various subcommittees. I have many years of consulting experience in the fields of Roofing, Waterproofing and Exterior Building Envelope disciplines.

Organizations
Roof Consultants Institute Construction Specifications Institute ASTM

Publications
Division 7 Technical Binders for Malarkey Roofing Products and Polyglass USA, Inc. CSI Phoenix Chapter Cactus Comments

Education/Credentials
Registered Roof Consultant - Roof Consultants Institute Registered Roof Observer - Roof Consultants Institute Certifified Document Technologist - Construction Specifications Institute Spray Fireproofing Special Inspector - International Code Council

Awards and Honors
Registered Roof Consultant - Roof Consultants Institute Registered Roof Observer - Roof Consultants Institute Certifified Document Technologist - Construction Specifications Institute Spray Fireproofing Special Inspector - International Code Council

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