Low Slope Roof Drainage

Proper drainage cannot be emphasized enough when discussing or reviewing the requirements of any well drained low slope commercial roof system figure 1.

Low slope roof drainage.

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. A traditional roof on a home is slanted. The building in figure 2 is located in the mid atlantic region near a large city on the east coast.

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. 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. Prudent designers would like the roof drains to be located at the low point of the structurally sloped roof deck. The building was unoccupied at the time of a cursory audit.

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. Consequently the roof drains must be located on the plumbing drawings up slope from the low point. One of the most common we see is the lack of proper drainage. Low slope roof drainage.

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