Purpose Of Gravel On Roof

On many flat roof low slope commercial buildings it s common to see gravel on top of the roof.

Purpose of gravel on roof.

Tar has a low melting point. Friday july 6 2018. A tar and gravel roof will generally last around 20 years although if they are well maintained and properly installed this kind of roofing has been known to last almost 40 years. Disadvantages of a tar and gravel roof.

Uv rays speed up asphalt deterioration and cracking when the asphalt is directly exposed to sunlight. Most houses with flat or nearly flat roofs are topped with built up roofing or tar and gravel roofing made from fiberglass based asphalt sheeting that is applied in layers with hot bitumen tar mopped on between. This is called built up roofing. The purpose of stone or gravel ballast on a flat roof published by justin on september 19 2019 september 19 2019 it is not unusual to find a gravel top coat on commercial roofing systems.

What is the purpose of the gravel on a flat tar roof. A flat or low slope roof is often not a suitable surface for shingles or other roofing materials because moisture can t flow off them. Built up roofing bur was the most common type of flat roof before modified bitumen and membrane roofing were developed. Talk to ten roofing contractors and you ll get ten answers on what the gravel is for but this seems to be the consensus.

One solution to this is a built up or tar and gravel roof where many layers of hot asphalt or bitumen tar paper and a waterproof membrane are applied and then covered with gravel. Gravel is used on flat roofs for two reasons. 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. A gravel or pea shingle on a roof serves two purposes.

One is to act as ballast to weigh down the covering surface and help prevent it being blown off in high winds. A bottom layer or two of insulation board multiple intermediate layers of tar or asphalt alternated with layers of roofing felt and a top layer of gravel. The purpose of gravel on a flat roof. Gravel provides shade to the top layer of asphalt tar protecting it from the ultraviolet rays in sunlight.

Bur consists of many layers. Built up roofs or burs also called a tar and gravel roof is a well established and popular style of flat roof that is made up of alternating layers of roofing felt or fiberglass and asphalt that is applied with heat which combine to make a long lasting sturdy roofing system. A tar and gravel roof is very heavy.