Spray Foam Professional - Fall 2012 - (Page 14)

ABAA NEWS TRANSITION MEMBRANES AND SPF BY LAVERNE DALGLEISH, EXECUTIVE DIRECTOR AIR BARRIER ASSOCIATION OF AMERICA, INC. Prep for pull test Inset: Pull test W hen spray polyurethane foam is used as an air barrier rather than a thermal insulation in a building, transition membranes are required around penetrations, for connections to roof air barrier materials, poured concrete foundations, windows, curtain walls, storefronts, louvers, exterior doors, changes in substrate planes, deflection joints, expansion joints, seismic joints, control joints and other intersections. Building materials will expand and contract in varying amounts based on their temperature and moisture content. Spray polyurethane foam will allow for a certain amount of movement of the substrate; however, when there are dissimilar materials next to one another (i.e., a metal framed window in a CMU wall), it would be impossible to say that the difference in expansion and contraction of the windows’ metal frame in relation to the wall would not create a crack in the spray polyurethane foam over a period of time. While these cracks may not have a major impact on the thermal performance of the spray polyurethane foam, any breach of the air seal will result in a loss of performance of the air barrier system. To ensure performance over time of spray polyurethane foam as an air barrier, transition membranes are used to make the connections between 14 SPRAYFOAM PROFESSIONAL | Fall 2012 materials before its installation. The transition membranes provide a backup seal in case the material movement is beyond what the sprayfoam material can withstand. Historically, transition membranes have been strips of self adhered membranes. These strips of membranes need to be installed in accordance with the manufacturer’s instructions, which include the installation of a primer on the substrate before the installation of the transition strips. The adhesion of the transition strips to the substrate is extremely important. Spray polyurethane foam needs a clean, dry and sound substrate. If, for example, transition strips were installed without a primer, it would not be unusual for the foam to peel the transition membrane from the substrate. If the substrate is not properly fastened (in this case by adhesion), the foam will pull it off. It has been shown that if the transition membrane has been installed with at least 16 psi adhesion when tested in accordance with ASTM D4541, it will be suitable to install spray polyurethane foam over it. It can be difficult to install a transition membrane in some locations, such as a brick ledge. In many cases, the brick ledge is not smooth and may not be clean; as such, achieving a 16 psi adhesion may not be possible. In this case, you would install a metal strip such as a J channel, which is mechanically fastened through the transmission strip, to the substrate. When the spray polyurethane foam is then installed, it will encapsulate the metal channel and fasteners. The proper installation of transition membranes before the start of the spray polyurethane foam installation will result in a smooth flowing job and an air barrier system that will continue to function over time. o The transition membranes provide a back-up seal in case the material movement is beyond what the sprayfoam material can withstand.” http://www.sprayfoam.org

Table of Contents for the Digital Edition of Spray Foam Professional - Fall 2012

EXECUTIVE DIRECTOR’S CORNER
PRESIDENT’S POST
FOAM BUSINESS NEWS
SPFA TODAY
ABAA NEWS
LEGISLATIVE UPDATE
SAFETY FIRST
BEHIND THE FOAM
2012 SPFA CONTRACTOR AWARDS
GETTING SUSTAINABLE ROOFING RIGHT
MILITARY STANDARDS AND SPRAY POLYURETHANE FOAM INSULATION – PART 2
IRAQ – U.S. MILITARY IN IRAQ BENEFITS FROM PERFORMANCE OF SPF
ASK THE EXPERT
UPCOMING EVENTS
INDEX OF ADVERTISERS/ADVERTISERS.COM

Spray Foam Professional - Fall 2012

http://www.nxtbook.com/nxtbooks/naylor/SPFQ0113
http://www.nxtbook.com/nxtbooks/naylor/SPFQ0412
http://www.nxtbook.com/nxtbooks/naylor/SPFQ0312
http://www.nxtbook.com/nxtbooks/naylor/SPFQ0212
http://www.nxtbookMEDIA.com