Low-Slope Commercial Roofing
The trend in high-performance cover boards has been the use of gypsum-based products that have been rendered water and mold resistant. Many of the products contain high levels of recycled materials, assisting in the procurement of LEED (Leadership in Energy and Environmental Design) credits. Calcination3 issues have been overcome with some gypsum-based products, permitting application of membranes in Type IV asphalt with no blistering of the membrane.
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Today's cover boards are available in thicknesses ranging from 1/4 to 3/4 inch. Boards are fabricated from various materials and have different properties, such as fire resistance, void bridging and wind uplift resistance. Product literature and system approvals from FM Global and Underwriters Laboratories should be reviewed carefully to identify the appropriate cover board for a project.
Cover boards are compatible with a wide variety of adhesives and hot asphalt, as well as mechanical fasteners. Again, manufacturers' literature and approvals should be reviewed carefully to determine the appropriate installation methods for specific projects.
1 A module is the measurement from the center of the high
rib to the center of the next high rib (or flute)
2 National Roofing Contractors Association bulletins
3 The release of chemically bound moisture within the gypsum
crystal when heated
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