The fiberglass applied outside on a balcony with a wood structure must be ready to undergo a lot of temperature variances here in Quebec due to freezing and thawing. Flexibility is not one of its attributes. The result is quite frequently that after a short time, micro cracks appear which causes water infiltration to begin. And there, it is the beginning of the problems, because once the cracks are apparent, the water is trapped under the fiber and the rot settles there very quickly.
On the other hand, the polychloride membrane (PVC) is flexible and able to withstand the jolts of mother nature.freezing and thawing…