Can Vapor Retarders Address Problems From Moisture in Concrete Roof Decks?

March 14, 2016
Publication: National Roofing Contractors Association's 2016 Annual Convention

Moisture entrapped within concrete roof decks is a major concern of the roofing industry. The NRCA (National Roofing Contractors Association) and others have reported numerous problems, including failures, due to moisture that migrates from the wet concrete deck into the roofing system after it has been installed. The presentation reviewed the issues including the quantities of water contained in roof decks and provided sampling of typical problems that we observed in roofing systems applied to wet concrete decks. Our prior studies have shown that providing a vapor retarder between the deck and the roofing system can mitigate the moisture migration problems. However, the industry still questions when it is safe to install the vapor retarder (and roofing system) and whether the system will continue to perform long term. SGH developed a procedure to evaluate the continuing performance of adhered vapor retarders as they age, investigating a few vapor retarders currently in the market. We provided a progress report of the ongoing laboratory testing. The presentation also reviewed other variables affecting the long-term adhesion of vapor retarders and outlined a testing program to continue our research into this matter.