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Self Adhering Window Flashings and Related Standards

Posted on 8/7/2013 11:41:48 AM By Bob Braun
  

In my last post, I reviewed the subject of water intrusion into building walls as related to window and building design changes that have occurred in the last twenty plus years.  Now, I will review a newer technology that is becoming more and more innovative and popular-self adhering window flashing.

First, let’s look at how and why this product has become more commonly used.  The design of many windows took a turn in the last 30 plus years with the innovation of the finned window.  The perforated perimeter fin allowed the installer to screw or nail the window to the building sheathing helping to speed the installation.  About the same time the use of “building wrap” became popular as an additional air seal intended to save energy.  Building wrap later became known as “weather resistant barrier” or WRB since the benefit of this product also included moisture protection as well.  Earlier perforated asphalt impregnated felt or rosin paper supplied in smaller rolls was used in a shingle lap fashion.  It soon became clear that not enough attention was being paid to the narrow space between the window frame and the wall stud/sheathing surfaces.  Water ingress into this area created havoc with the wall and window materials.  Flashing had usually been done using asphalt impregnated paper on a roll from to six to twelve inches wide.  The photo below shows attaching the fin to the sheathing using nails (screws are much preferred) before the subsequent application of the self adhering flashing. 

The 2008 paper titled “Installing and Flashing Windows Correctly” from Fine Home Building magazine, provides a good photo summary of the application of the flashing and the perimeter fin sealant as well as the interior rough opening foam sealant.

In the early 2000’s the American Architectural Manufactures Association (AAMA) initiated a closer look at self adhering flashing adhesives and began developing standards and test methods.  Manufacturers were using various adhesives and tape materials and some more effective than others.  All self adhering flashing must be applied to a clean dry surface at an appropriate application temperature for maximum effectiveness.      

Now, what has happened more recently in the development of self adhering flashing standards’ development?  In 2007, the AAMA 711 Standard (Voluntary Specification for Self Adhering Flashing Used for Installation of Exterior Wall Fenestration Products) was published; it was updated earlier this year.  AAMA 711-13 (available here) references many industry standards from ASTM and AAMA which include:


  • AAMA 800-10, Voluntary Specifications and Test Methods for Sealants
  • ASTM C734-06(2012), Standard Test Method for Low-Temperature Flexibility of Latex Sealants After Artificial Weathering
  • ASTM C765-97(2011), Standard Test Method for Low-Temperature Flexibility of Preformed Tape Sealants
  • ASTM D3330/3330M-04(2010), Standard Test Method for Peel Adhesion of Pressure-Sensitive Tape
  • ASTM E331-00(2009), Standard Test Method for Water Penetration of Exterior Windows, Skylights, Doors, and Curtain Walls by Uniform Static Air Pressure Difference
  • ASTM E631-06, Standard Terminology of Building Constructions
  • ASTM E2112-07, Standard Practice for Installation of Exterior Windows, Doors and Skylights
  • ASTM G155-05a, Standard Practice for Operating Xenon Arc Light Apparatus for Exposure of Non-Metallic Materials

And as mentioned in several of my earlier posts, the completion of ASTM E2112 - 07 Standard Practice for Installation of Exterior Windows, Doors and Skylights provides many details on the use of flashings, sealants and foam sealants as well.


With the completion of this post, I leave my review of water intrusion into building walls for now.  I have certainly not reviewed all of the related wall issues (e.g. one window manufactures provides 80 different instructions depending on the specific window or door design and the design of the building wall).  If you have a specific issue you would like me to touch on, please leave a comment below.


In my next several posts, I will begin to focus on recent developments in sustainability issues for sealants and industry plans to develop PCRs (Product Category Rules) and EPDs (Environmental Product Declarations).  In my next post, I plan to review some of the history for the sustainability issue before moving onto the new initiatives currently in process.



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