STP789

    Can Wet Roof Insulation Be Dried Out?

    Published: Jan 1983


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    Abstract

    Nondestructive techniues are being widely used to locate wet insulation in compact roofing systems. Now that wet insulation can be found, breather vents and so-called “breathable” membranes are being promoted to dry out wet insulation, thereby recovering its thermal effectiveness.

    Our exposure tests in New Hampshire indicate that the above venting methods are all rather ineffective in drying sealed specimens of perlite and fibrous glass roof insulation. It would take many decades to dry our specimens at the rates we measured over the past two years.

    Cross-ventilation within the insulation increased the rate of drying. For perlite insulation, the faster rate would still result in a drying time measured in decades. For fibrous glass insulation, the drying time was reduced to 13 years.

    We have succeeded in drying fibrous glass insulation in a roof by removing the water with a vacuum cleaner. In a series of tests with a total duration of 134 h, about 0.42 m3 (110 gal) of water was removed from a 17-m2 (180-ft2) area of 38-mm (1.5-in.)-thick insulation. Before the water was removed the insulation had only 21 percent of its dry insulating ability; afterward it had 83 percent.

    Keywords:

    roofs, roofing, thermal insulation, moisture, vents, venting, drying, water removal, vapor retarder


    Author Information:

    Tobiasson, W
    Research Civil Engineer, Research Civil Engineer, Research Civil Engineer, and Civil Engineering Technician, U.S. Army Corps of Engineers, Cold Regions Research and Engineering Laboratory, Hanover, N.H.

    Korhonen, C
    Research Civil Engineer, Research Civil Engineer, Research Civil Engineer, and Civil Engineering Technician, U.S. Army Corps of Engineers, Cold Regions Research and Engineering Laboratory, Hanover, N.H.

    Coutermarsh, B
    Research Civil Engineer, Research Civil Engineer, Research Civil Engineer, and Civil Engineering Technician, U.S. Army Corps of Engineers, Cold Regions Research and Engineering Laboratory, Hanover, N.H.

    Greatorex, A
    Research Civil Engineer, Research Civil Engineer, Research Civil Engineer, and Civil Engineering Technician, U.S. Army Corps of Engineers, Cold Regions Research and Engineering Laboratory, Hanover, N.H.


    Paper ID: STP29475S

    Committee/Subcommittee: C16.16

    DOI: 10.1520/STP29475S


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