Flat Roof Roof Drainage Plan

There are three types of drain systems commonly used on flat roofs.

Flat roof roof drainage plan.

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. Or 12 drains required. Determine 100 year 1 hour rainfall rate used for location of building. The gr52 can withstand 0 352 gallons per square foot or 1 4 gallons per panel.

Size horizontal storm drainage piping. Often the flat roof has a slight pitch in the rafters. Poor drainage can lead to serious issues with flat roofing from leaks to structural damage. Take the roof s total square footage and divide by the total square footage handled by one drain.

The one challenge with flat roofing is ensuring proper drainage. The grs gr52 panel size is 24 x 24 x 2 125. Of course the best designed flat roof has the correct amount of pitch to drain the water off naturally. 50 000 4 400 11 36.

As water flows to the edge a metal diverter is usually placed at the eave to prevent dripping at walkways. A correctly build flat roof will drain the rainwater quickly and effectively into the gutters without allowing water to collect in depressions and pond on the surface of the roof leading to the build up of silt deposits on the roof and stresses in the membrane when the water freezes a small amount of ponding is inevitable and it should not reduce the performance of the roof covering. Green roof solutions gr32 and gr52 drainage panels come in 24 x 24 interlocking squares constructed of 100 recycled high density polypropylene hdpp. Most draining systems on flat roofs have a poor design or are not correctly installed.

A flat roof will often have a parapet or false wall sur. The result is the number of drains needed. Each of these systems has its own pros and cons. A pitch of 1 4 per foot 2 percent slope is often used to help prevent wa ter from ponding on the roof.

There are three types of drain systems on a flat roof. Ipc provides four steps to size the roof drains on a building. Using tools from the international plumbing code ipc it s not that hard. So often we find that inner drains are high on the roof causing water to pool around them.

Unlike other roofing types that are slanted or sloped to allow water to drain automatically flat roofs need a built in drainage system to help remove moisture and debris. It is a requirement of building regulation part h that adequate provision is made for rainwater to be carried from the roof of the building. Sented on the roof plan. There are roof coating products available if there isn t enough slant or slope to accomplish this.

Select number of roof drains and calculate the roof area sloped to each drain. Your building and location can help determine which drain will fit your roof needs.