Boyle Bros. funeral home in Framingham discovered a leak this winter and called us to look at it, on the flat section of there building a rubber was installed over a tar and gravel roof. A half inch fiber board was mechanically fastened over the tar and gravel, the problem with fiber board in a go over application is it acts like a sponge and sucks up water before showing any signs of a leak.
In Boyle Bros. case the roof had been leaking for years from a hole in the rubber and until the weight of this winters snow squeezed the water from the saturated fiber board.
We stripped off the roof and installed a new rubber roof with half inch recovery board instead of fiber board. With a warranty of ten years on our labor and fifteen years on materials we included an inspect of the roof in the fall