Why Do People Put Rocks On Flat Roofs

The membrane is.

Why do people put rocks on flat roofs.

There are several reasons flat roofs have stones. That s all there is to it. This is the protective cover that keeps the layers of tar and bitumen from deteriorating in the weather. Yes it is for wind lift.

One thing it would do is make the roof more resistant to sun damage as much of the roof is not directly exposed covered by rocks. The stones keep the tar paper in place and prevent it from buckling or blowing away in a high wind. I think some people do it because they like the look. Rocks are placed on commercial flat roofs for many different reasons if the roof is what is called a ballast roof it is not fastened or adhered down throughout the whole roof.

If the roof is a built up roof made with layers of tar and bitumenous sheets it creates a wear layer for the roof. Reminded me of haiti where they use rocks of any type to hold the tin sheets on through a storm. The gravel provides a better grip for foot traffic when conducting maintenance or repairs. The gravel also acts as a protective measure to prevent natural debris such as leaves.

It s also a bit of an aesthetic nicety on more modern roofs just for the crack as it were. Remember trad italian roofs have much bigger overhangs on the eaves the bit which overhangs the long sides of a pitched roof and also on the verges which overhang the gables. The gravel prevents sun hail errant baseballs etc from damaging the membrane the all important moisture seal created by the tar paper and tar.