A gravel roof is one of the oldest systems used in the roofing industry. Typically, these roofs were two or three ply rag felts mopped down and then covered with gravel for durability and also for helping with evaporation of water as the rock heated up. It also served a purpose to protect against wind uplift by providing ballast or weight.
One of the biggest downfalls of this system is that finding the leak can be very difficult and in some cases, impossible. The additional weight is hard on the building’s structure, as well. Repairs will have gravel moved around and many times, not put back where it was. This gravel usually weighs at minimum 600-800 pounds per 100 square feet. Therefore, even a small building of 5,000 s.f. can have seventeen to twenty tons of weight overhead, stressing even the best laid system.
With the hurricanes in the 90’s and early 2000’s, the gravel aggregate became air born debris. This system now usually requires a parapet wall for high velocity wind zones.
With our roof system, we simply hydrovac the gravel. This is a clean, quick and efficient means to get rid of the excess and useless material. In some instances, we can put the excess somewhere on site at the owner’s request or dispose of it properly, if unwanted.
With the spray foam, we feel fastening of the existing substrate is very beneficial after the rock removal and before the new foam application. With FM requirements met, the owner may receive some savings on their insurance premiums in the future.
In the end, your roof will weigh only 5-10% of what the old one did and is highly insulated and water tight. Structural stress is relieved and leaks and building settlement is reduced or eliminated.