Low Slope Roof Drainage

The building in figure 2 is located in the mid atlantic region near a large city on the east coast.

Low slope roof drainage.

Consequently the roof drains must be located on the plumbing drawings up slope from the low point. A traditional roof on a home is slanted. Here at boak sons our commercial roofing repair technicians are experts in spotting potential problem areas on low slope roofs. Typically though there is a steel beam at the low point which prevents the installation of the roof drain at the low point.

Proper drainage cannot be emphasized enough when discussing or reviewing the requirements of any well drained low slope commercial roof system figure 1. Prudent designers would like the roof drains to be located at the low point of the structurally sloped roof deck. One of the most common we see is the lack of proper drainage. 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.

This allows water to run down the roof into the gutters. 4 x 5 downspout scupper box scupper with sleeve closed top scupper with sleeve open top 7 gutter shop fab gutter more search low slope. Low slope roof drainage. 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.

On a flat roof you don t get the same slope so the water has nowhere to go.