Roof Drain Layout

It is very critical to position drains for maximum effect.

Roof drain layout.

Factors which affect proper roof drainage are deck slope drain size and placement of drains. Sizing a roof water drain the first step in sizing a roof drain is to calculate the surface area of the roof that the drains will be covering as well as the average hourly rainfall rate at the building location. Install a drain at most 50 ft. So often we find that inner drains are high on the roof causing water to pool around them.

Use at least two drains where possible. The roof is sloped towards the drain through either tapered insulation or through joist modifications below the roofline. Most draining systems on flat roofs have a poor design or are not correctly installed. The next step is to determine each roof area that will be served by a separate leader drain pipe scupper or downspout.

Limit roof area to 25 000 sq. There are three types of drain systems on a flat roof. From the edge of a valley. The sizing of roof drains must be large enough to quickly carry away all water entering the roof drains.

General roof drain system guidelines. Following are some basic design guidelines to consider as part of your project courtesy of jay r. Install a drain at most 50 ft. This form of roof drainage is preferred if a clean exterior appearance is desired.

The full flow capacity of a drain is not realized until the water reaches approximately 2 5 above the inlet in a four inch drain and 3 5 in a six inch drain.