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Proceedings Paper

The case for using a sacrificial layer of absorbent insulation in the design of flat and low-sloped roofing
Author(s): Gregory R. Stockton
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Paper Abstract

Beginning about twenty-five years ago, there was a marked increase in the number of single-ply membrane roof designs used to cover and waterproof flat and low-sloped building roofs. Over the past ten years, there has been a substantial increase in the number of installations of white and more reflective single-ply roof systems, mostly using high density cellular foam insulation in the substrate for insulation. A major factor in the increase in the popularity of these highly insulated and more reflective roof systems is the fact that many governments began offering incentives for building owners to use reflective coverings and better insulated roofs. Now, owing to the energy efficient requirements for the design and construction of new buildings put forth in ASHRAE Standard 90.1, “Energy Standard for Buildings Except Low-Rise Residential Buildings” and the world’s apparent desire to be “green” (or at least appear to be), more and more roof designs will include these reflective single-ply membranes, which use the cellular foam insulation boards to meet these requirements. Using a lower density traditional insulation will mean that the roof will have to be very thick to comply, increasing the costs of installation. High density cellular foams do not absorb water until time, vapor pressure drive, UV and thermal shock break down the foam and it becomes more absorbent. This could be 5-7 years or longer, depending on the roof construction and other factors. This means that any water that enters the roof through a breach (leak) in the membrane goes straight into the building. This is not a good consequence since the failure mode of any roof is water entering the building. Keeping the water out of the building is the purpose of the waterproofing layer. This paper reviews the techniques of moisture testing on building roofs and infrared (IR) thermography, and puts forth the idea and reasoning behind having a sacrificial layer of very absorbent insulation installed in every flat and low-sloped roof so that when a breach occurs, it can easily be found, documented and repaired during an annual infrared inspection; as IR is an effective predictive maintenance technique and condition monitoring best practice for roof maintenance.

Paper Details

Date Published: 22 May 2013
PDF: 8 pages
Proc. SPIE 8705, Thermosense: Thermal Infrared Applications XXXV, 870504 (22 May 2013); doi: 10.1117/12.2018294
Show Author Affiliations
Gregory R. Stockton, Stockton Infrared Thermographic Services, Inc. (United States)

Published in SPIE Proceedings Vol. 8705:
Thermosense: Thermal Infrared Applications XXXV
Gregory R. Stockton; Fred P. Colbert, Editor(s)

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