Originally Posted by HILAKE2
I have a question.
All the flat roofs I've seen around here have loose rocks scattered on them....what is the purpose of those?
Like a commercial size building??
If you're talking about river rock on the roof...it's main purpose is ballast for the rubber epdm beneath it and for protection of the rubber membrane. It provides a walking surface although almost every roof like that has walk pathway, stone pavers etc. for pathway.
The rubber is sprayed down with a asphalt based adhesive and rock is spread over that. The adhesive also helps over time with aging rubber, in the summer the adhesive softens up and "self levels" into cracks or dry rubber
If you're talking about little white granules , then that is just the cap sheet granules getting loose over time on a cap sheet roof