There are various occasions when roof system specifications call
for flood testing, such as to determine quality assurance of a
newly installed roof system or locate a leak source. But sometimes,
flood testing is recommended when it isn't appropriate. Following
is a discussion about NRCA's guidelines for flood testing.
NRCA does not recommend conducting flood tests as part of a
routine quality-control or quality-assurance program for a new roof
system. One reason is flood tests sometimes are solely and
incorrectly relied on to determine roof system quality. Flood
testing alone does not forecast a properly designed or installed
roof system. For example, a flood test will not provide information
about service life or evaluate a roof system's ability to resist
wind or impact loads.
Flood testing also is not appropriate for identifying potential
leak sources. Roof systems are designed to be weatherproof, not
waterproof. A weatherproof roof resists the passage of water with a
minimal amount of hydrostatic pressure (flowing water);
waterproofing systems prevent the passage of water under
hydrostatic pressure (standing water). For example, water leakage
may occur at roof drain flashings with flood testing. Flood testing
exposes roof drains to hydrostatic pressure, and roof drains are
not designed to be leak-free under such unrealistic...
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