07/01/2013

Spray Foam: When and Why?

Reasons to consider polyurethane solutions for reroofing

By Richard L. Fricklas

 
  • /Portals/1/images/OnlineImages/2013/0713/rr/1-robot.jpg

    Robotic SPF application

  • /Portals/1/images/OnlineImages/2013/0713/rr/2-base.jpg

    Here, a base coat is applied over a layer of sprayed-in-place foam.

  • /Portals/1/images/OnlineImages/2013/0713/rr/3-wetvac.jpg

    Crews utilize a high-pressure, low-volume wet-vac on an SPF installation.

Year in and year out, it has been estimated that two-thirds of all commercial roofing activity is related to reroofing and re-cover rather than new construction.

Decisions on what, when, and where to reroof may be based in part on leakage, although timing may also be related to an overall corporate financial plan (spend it now because funds may not be available later).

The choices for reroofing are generally categorized as:

  • Traditional bituminous built-up roofing
  • Polymer-modified bituminous roofing
  • Single ply polymeric roofing
  • Metal roofing panels
  • Sprayed-in-place polyurethane foam (SPF)

Three Considerations for Foam
A sprayed-in-place foam solution for reroofing might be the best choice for you if:

1) Your existing roof already has two membranes, in which case it has already met the maximum permitted by building code. However, SPF is extremely light (less than 1 pound per square foot) and is usually exempted from that code limitation. If the existing roof is surfaced with gravel or ballast, removal of that surfacing and replacement with SPF will actually reduce some of the dead load on the structure.

2) The existing roof system is aged, which typically means it is under-insulated. One inch of wood fiber or perlite board would have an R-factor of 2.8, so applying two inches of SPF on top would add 11.2 (in•h•ft2/BTU), and substituting a reflective coating on the foam, compared to a dark-colored gravel, would reduce air conditioning load as well.

3) The system is fully adhered. Many single ply roof systems are partially fixed to the structural roof deck, especially those using mechanical fasteners. These systems may flutter and balloon under high wind load. SPF systems are fully adhered to the substrate and can serve as an air barrier as well as the roof membrane. See Building Science.com BSI-019 Uplifting Moments—Roof Failures, Joseph Lstiburek, 2009


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When choosing a metal-clad building for your next construction project, consider Morton Buildings, Inc., and their designBUILD team, we’ll make your dream a reality.

Visit our website today to learn about the design flexibility of a Morton building and the endless possibilities of partnering with our designBUILD team.

Wood construction is both cost and energy efficient. Check out Morton Buildings and our designBUILD team online today to discover all the benefits of post-frame construction.

We Can Help You Reduce Energy by 30%

Our mission is to help our customers manage their buildings' energy costs, improve reliability, and enhance performance while having a positive impact on the environment.
CLICK HERE to find out how.


Mitsubishi Electric’s H2i R2-Series heat pumps provide 100% heating capacity down to 0° F and simultaneous heating and cooling down to -4° F delivering year-round comfort, regardless of climate zone.

 
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