Low Slope Roof Drainage

Low slope roof drainage.

Low slope roof drainage.

A traditional roof on a home is slanted. The asphalt roofing manufacturers association arma recommends that roof designs provide adequate slope minimum of inch per foot to ensure that the roof drains freely throughout the life of the building and to thereby avoid the effects of ponding water. Keeping the roof adequately drained can help keep water from sitting on the roof. Here at boak sons our commercial roofing repair technicians are experts in spotting potential problem areas on low slope roofs.

Prudent designers would like the roof drains to be located at the low point of the structurally sloped roof deck. Through building drains upper right in the sketch become clogged internally and burst flooding the building or leaks occur around the drain itself where it penetrates the roof. This allows water to run down the roof into the gutters. On a flat roof you don t get the same slope so the water has nowhere to go.

The building was unoccupied at the time of a cursory audit. Proper drainage cannot be emphasized enough when discussing or reviewing the requirements of any well drained low slope commercial roof system figure 1. The building in figure 2 is located in the mid atlantic region near a large city on the east coast. On flat or low slope roofs that drain to one end lower right in the sketch especially if the building rear wall does not include a projecting eave or soffit a clogged gutter or downspout send water down the building rear wall flooding the structure through its wall or through windows.

Typically though there is a steel beam at the low point which prevents the installation of the roof drain at the low point.