Why Do Buildings Have Gravel On The Roof

Walked on gravel tends not to hurt the seal of the tar underneath.

Why do buildings have gravel on the roof.

Also the gravel acts as a wick to pull up any water left on the roof after scuppers or gutters lead excess water away. This surfacing keeps the felts protected from the sun s uv rays which damage the felts over time. As gravel cannot protect tarpaper surfaces where they rise vertically from the roof such as on parapet walls or upstands the felts are usually coated with bitumen and protected by sheet metal flashings called gravel stops. To weigh down or secure the roofing material as is the case with single ply flat roofs.

Roof penetrating structures can cause leaks. The gravel embedded on the top coat of asphalt the flood coat protects the underlying layers from the elements including ultraviolet rays and natural threats like roof hail damage or heavy rains. To protect the underlying layer of roofing materials as is the case with built up roofs burs. Can i use pea shingle size 10 15mm does anyone.

Such structures include plumbing vents pipes gas lines and other building elements. The only purpose of rock on a membrane roof is to hold the roof system down. He told me that i needed to lay some gravel on the flat roof. Gravel is used on flat roofs for two reasons.

Tar has a low melting point. The gravel covers a tar roof. They are especially vulnerable to leaks anywhere a structure rises up through the surface of the roof. In the summer it gets pretty soft and if left to its own devices would flow to the lowest point on the roof.

Tar and gravel roofs add substantially more weight to the building structure. In a typical tar and gravel roof which by the way is gradually being supplanted by gravelless roof systems you put down a layer of tar paper then tar and finally gravel. After you add the layers of tar supporting fabrics and the top layer of gravel your roof can be an extra 5 10 lbs. Per square in heavier than before.

This added weight can strain your roof underlying substrate and facility as a whole. Walking on the tar would hurt the tar s seal fast. Flat roofs have one thing in common with sloped shingle roofs.