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Title
The shortcomings of using prescriptive specifications with emerging roof technologies
The shortcomings of using prescriptive specifications with emerging roof technologies
Date
9/2011
9/2011
Author(s)
Rene Dupuis; Mark Graham
Rene Dupuis; Mark Graham
Page(s)
Keyword(s)
specifications; moisture; content; lightweight structural concrete; moisture test; low rise foam adhesive
specifications; moisture; content; lightweight structural concrete; moisture test; low rise foam adhesive
Abstract
Prescriptive specifications often are used by designers to define roof system designs. In many instances, these prescriptive specifications are out of date and inconsistent with current roofing technology. With the general public’s sudden interest in using roof systems as reflective surfaces or platforms for vegetative roof systems or renewable energy systems, designers’ reliance on prescriptive roof specifications is of increasing concern because they usually do not properly address the specific performance attributes necessary for roof systems and changing materials and technology. One already obvious example of the above-mentioned concern is a shift occurring within the concrete industry to using porous, lightweight aggregates in structural concrete instead of normal weight aggregates, such as those used in normal weight structural concrete. Although the benefit of using lightweight aggregates in structural concrete is obvious—lighter weight concrete structures—the unintended consequence is the concrete’s lightweight aggregate will store and release moisture to the detriment of the installed roof system. This paper will review methods for determining the wetness (and dryness) of concrete substrates to ascertain the appropriateness for these substrates to receive roofing materials. Because the flooring industry has similar concerns, test methods used by the flooring industry also will be considered.
Prescriptive specifications often are used by designers to define roof system designs. In many instances, these prescriptive specifications are out of date and inconsistent with current roofing technology. With the general public’s sudden interest in using roof systems as reflective surfaces or platforms for vegetative roof systems or renewable energy systems, designers’ reliance on prescriptive roof specifications is of increasing concern because they usually do not properly address the specific performance attributes necessary for roof systems and changing materials and technology. One already obvious example of the above-mentioned concern is a shift occurring within the concrete industry to using porous, lightweight aggregates in structural concrete instead of normal weight aggregates, such as those used in normal weight structural concrete. Although the benefit of using lightweight aggregates in structural concrete is obvious—lighter weight concrete structures—the unintended consequence is the concrete’s lightweight aggregate will store and release moisture to the detriment of the installed roof system. This paper will review methods for determining the wetness (and dryness) of concrete substrates to ascertain the appropriateness for these substrates to receive roofing materials. Because the flooring industry has similar concerns, test methods used by the flooring industry also will be considered.