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Focus on Roofing: Implications of Adhesives and Sealants for Fire Ratings in Low-Sloped Roofing Assemblies

Posted on 10/9/2012 10:02:39 AM By Bob Braun
  

 roof, building, construction, adhesives

This is the thirteenth blog in the ASC Building Products series.  This blog will detail of several low-sloped related test methods and how and where they can be conducted.  I will also discuss the various codes that reference the test methods and the requirement levels that have been set.  In this blog I will include a description of several test methods and codes required to meet the essential criteria for these roofing assemblies i.e. wind and fire.  And Blog #14 will include water-proofing requirements.  On might wonder why an adhesive or lap sealant etc. used in attaching the low-sloped water proofing membrane or insulation board even requires fire testing since the amount used is so small in comparison to the other components.  Well, remember as highlighted in prior blogs, that roofing codes are based on testing assemblies and minimum performance must show conformance as an assembly.  The description of ASTM E108 below will further embellish this point.

In Blog #12 I provided a list of the many organizations providing standards for roofing assemblies which involve the use adhesives and sealants for attachment, overlap joining, and weather proofing.  You can review this list if desired and search the provided links as well.

In Blog #11 I previously explored the primary wind uplift tests so here I will begin discussing the primary fire related test methods.  ASTM E108 Standard Test Methods for Fire Tests of Roof Coverings and also a similar UL 790 test... This fire-test-response standard covers the measurement of the relative fire characteristics of roof coverings under simulated fire originating outside the building. It is applicable to roof coverings intended for installation on either combustible or noncombustible decks when applied as intended for use. The following test methods are included: intermittent flame exposure test, spread of flame test, burning brand test, flying brand test, and for some roof deck structures e.g. fire-retarded treated plywood (of course containing adhesives), a rain test and weathering test.  The rain test for example is conducted in accordance with Method A of Test Method ASTM D2898 Standard Practice for Accelerated Weathering of Fire-Retardant- Treated Wood for Fire Testing. 

Click here to view a brief video of the Burning Brand Test.

Now let’s drill down on the Factory Mutual (FM) standards and the relation to building codes:

The Model and local building codes can require conformance to level Class A, B, or C of ASTM E108/UL 790 or to a more stringent FM Class I requirement.  FM 4450 Approval Standard for Class I Insulated Steel Roof Decks specifies the testing details while FM 4470 is the Approval Standard for Class I Roof Covers and specifies the requirements for internal fire, external fire, wind uplift, foot traffic, corrosion resistance, plastic parts fatigue, impact resistance, and susceptibility to heat damage. A less stringent UL 1256 Fire Test of Roof Deck Constructions includes an under deck fire test only which details the fire test methods to evaluate the performance of metallic and nonmetallic roof deck constructions subjected to internal (under deck) fire exposures for the purpose of determining the contribution of the roof covering material, insulation, and other components of the roofing system to the spread of fire within a building

Depending of many details such as the roof construction details, geographic location, building use, and building height, the local/Model Codes will require a specific level of testing and performance.  Refer to the NRCA link International Building Code (IBC) and www.iccsafe.org for your specific requirements. 

Below I provide links to videos, and drawings to exemplify both installation techniques and testing details…

Video: Installing perimeter wall flashing with termination bar and sealant.

Video: Installing a fire sheet on wood deck to meet a Class A Fire Rating.

Video: Installing a single ply membrane with adhesive.

 

construction, test decks, building, decks
 

 test decks, building, construction, wood decks, decks, adhesives, sealants, glue

Composition of the A, B, and C Brands and the wood test decks for ASTM E108 Testing

So it is now evident that a great deal of testing is required to qualify a commercial building low-sloped roof assembly that includes all components including the assembly’s adhesives and sealants.  Many of the test methods referenced above will also overlap into other roofing types and assemblies which I will feature in future blogs.  And as a final comment, I need to mention that in addition to the fire ratings detailed here, there are also requirements for surface flame spread and smoke development ratings as tested by ASTM E84.  This is however a run as material test in a 24 Ft long test tunnel.  A web search for your specific test of interest will provide many ads for testing companies and their locations.

 astm, adhesives, sealants, building, construction

In Blog #14, I plan to focus specifically on the sealants and adhesives used in water proofing low sloped roofing joints, laps, and penetrations along with the related test methods. 



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