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Cover Board Use is the Roofing Industry's Solution to Protect Roof Insulation and Prevent Blistering in Low-Slope Roof Systems

Date: May 15, 2014 (847) 493-7548

Cover Board Use is the Roofing Industry's Solution to Protect Roof Insulation and Prevent Blistering in Low-Slope Roof Systems

Professional Roofing's May issue provides a history of cover board use, details different types and shows why cover board use with low-slope roof membranes is good roofing practice in protecting insulation and preventing blistering

Rosemont, Ill. — Thirty-five years ago when incidences of degassing and vapor release between polyisocyanurate roof insulation and hot-applied built-up roofing materials began to cause wide-spread blistering in low-slope roof systems, the National Roofing Contractors Association (NRCA) issued a bulletin advising roofing contractors to install wood fiberboard, perlitic board or glass fiber board insulation between the polyisocyanurate roof insulation and built-up roofing to stop blistering. In the years since, cover boards have become a standard method to enhance overall roof system performance for all low-slope roof systems.

Cover boards are available in a variety of sizes and materials. A history of their evolution to become the roofing industry's solution to roof membrane blistering and to provide protection for low-density roof insulation from NRCA's perspective is featured in "Covering your options," an article in the May issue of NRCA's trade magazine, Professional Roofing. The article, written by Jason Wilen, AIA, CDT, RRO, and an NRCA director of technical services, also provides detailed descriptions of the many cover board types that are used in low-slope roof systems.

Common cover board types used with low-slope roof systems include:
  • Wood fiberboard
  • Perlite
  • Glass-mat-faced gypsum
  • Fiber-reinforced gypsum
  • Mineral fiber
  • High-density polyisocyanurate
  • Cement
  • Asphalt core
"The article helps roofing contractors and roof system designers select an appropriate coverboard for a specific situation," Wilen explains.

According to the article, it is important to review a roof membrane manufacturer's literature or consult with its technical staff before selecting a cover board. In addition, many roof membrane manufacturers' extended warranty terms require the use of cover boards beneath low slope roof membranes.


The official publication for NRCA, Professional Roofing informs, educates and engages readers by providing timely, useful information and focuses on quality, innovation and responsiveness to readers' needs to help every roofing professional succeed. For more information, visit www.professionalroofing.net.

NRCA is one of the construction industry's most respected trade associations and the voice of roofing professionals and leading authority in the roofing industry for information, education, technology and advocacy. It represents all segments of the roofing industry, including contractors; manufacturers; distributors; architects; consultants; engineers; building owners; and city, state and government agencies. NRCA's mission is to inform and assist the roofing industry, act as its principal advocate and help members in serving their customers. NRCA continually strives to enhance every aspect of the roofing industry. For information about NRCA and its services and offerings, visit www.nrca.net.

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