Focus on Roofing: Adhesives and Sealants for Asphalt Shingle Roofing Systems

Posted on 12/14/2012 6:30:06 PM By Bob Braun

 roof, adhesives, sealants, roofing adhesives, construction, roofing projects, roof projects, building

This blog continues the ASC Building Products series for roofing which began with ASC Blog #10. In the previous Blogs (#10 to #16) I focused on adhesive and sealant applications for low-sloped commercial roofing and residential and light commercial applications for clay and concrete tile adhesives.  This Blog will conclude my focus on roofing applications even though I recognize that many niche roofing assemblies such as….have not been featured.

In most parts of the USA, the asphalt shingle is the most popular product for residential sloped roofing applications.  I will begin the asphalt shingle discussion with the most obvious adhesive/sealant feature…the lower factory applied adhesive strip that greatly enhances wind resistance.  To begin you may want to view a video on how asphalt shingles are manufactured.

Asphalt shingles contain a strip of factory applied adhesive that is activated by the sun's heat after installation and seals each shingle to the next course. The seal strip also provides much of a shingle's resistance to wind uplift. Shingles with factory-applied adhesive also have a strip of clear polyester film applied to each shingle to prevent the sealing strips from bonding the shingles together when packaged as shown in the video link above.  Later, the plastic film strips do not have to be removed since they do not align with the adhesive once installed.

Another use of adhesive, for the installation of asphalt shingles, occurs along the starter course at the roof eve where plastic roof cement is used between the roof felt and the starter course as demonstrated in this video,

Now let’s take a look at the composition of asphalt shingles.  Many years ago now the technology of incorporating a fiberglass layer in the asphalt shingle resulted in greater durability for this product.  The illustration below demonstrates this concept.  As a result these shingles also became stronger and more durable enabling longer warrantee periods.  The very common “three tab shingle” is shown in the photo below.

 asphalt shingle, roofing, building, construction, roofing projects, roof projects  roof, building, construction, adhesives, sealants, adhesive building projects, adhesive roofing projects, roofing projects
Layers in an asphalt shingle   Typical valley detailing

The roof of modern buildings has become a more important architectural feature each year.  The barely visible low sloped roof of the ranch house of the 1950’s has evolved to the more pitched and elaborate roof of today.  Shingle designers have invented ever more interesting shapes and textures to help enhance the roof appearance.  The Heritage® product shown below exemplifies these features and illustrates the use of a special secondary Tamko® adhesive used for preventing wind uplift.

construction, building, roofing projects, roofing, adhesive projects

Now let’s take a look at the standard and code development work.  The Asphalt Roofing Manufacturers Association (ARMA) issued a circular after the 2004 hurricanes in Florida.  This paper describes various wind zones and the requirements based on ASTM testing and now incorporated into both Florida and ICC Codes.

ASTM Committee D08 which creates and maintains most technical standards for asphalt shingles and roll-roofing.  However, as I discussed in Blog #16, evaluations are now also being done using recently developed wind machines as well as the hurricane force wind machine.  There are currently 15 asphalt shingle related standards in D08 and 10 more under other ASTM construction related committees.  Included is the standard specifications for ASTM D225-07 Standard Specification for Asphalt Shingles (Organic Felt) Surfaced With Mineral Granules and ASTM D3462/D3462M-10a Standard Specification for Asphalt Shingles Made from Glass Felt and Surfaced with Mineral Granules .  There are several uplift and wind resistance tests as well like the recent edition of ASTM D3161/D3161M-12 Standard Test Method for Wind-Resistance of Asphalt Shingles (Fan-Induced Method) .

And what is the role for sealants?  Like other roofing products, asphalt shingle roofs have numerous gutter, conduit, and pipe penetrations as well as skylights, chimneys, and wall and valley flashings.  Many of these will require a high movement-performance roofing sealant but some are sealed with a fibred asphalt based roof sealant or mastic as well.  One major manufacturer provides nine different formulations for the many roofing situations encountered with performance geared to substrate type, wet or damp situations, and joint movement expectation.

In Blog #18, we will move off the roof and begin a discussion of building wall applications for sealants and adhesives.  The many functions these products perform, and the existing and developing codes and testing standards for these products, will be a big part of the upcoming blogs as well. 


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