NRCA has received several reports of corrosion of metal components with low-slope membrane roof systems containing specific fiberboard insulation products. Because this issue presents possible roof system performance and worker safety issues, you should be aware of circumstances that may pose safety concerns and ways to identify whether fiberboard insulation is problematic.
Reports of problems
NRCA contractor members in several U.S. regions have reported significant corrosion of roof assemblies' metal components that directly contact fiberboard insulation. The reports show two general problem-causing scenarios.
In one scenario, the fiberboard insulation had been used as a cover board that was mechanically attached in an insulated low-slope membrane roof system configuration. Significant corrosion of the metal mechanical fasteners and metal fastener plates used to attach the fiberboard cover board is reported.