Flat Roof Drainage Design Guide

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

Flat roof drainage design guide. The drainage requirements for flat roofs on buildings present some special problems that we describe and illustrate here. Along with the benefits of a flat roof come unique challenges. Having sufficient drainage on a flat roof is vital. Your building and location can help determine which drain will fit your roof needs.

There are roof coating products available if there isn t enough slant or slope to accomplish this. Ipc provides four steps to size the roof drains on a building. According to bs 6229 bs 8217 flat roofs should be designed with minimum falls of 1 40 to ensure a finished fall of 1 80 can be achieved allowing for any inaccuracies in the construction. Take the roof s total square footage and divide by the total square footage handled by one drain.

On many occasions drains are too high and water cannot flow off. 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. Flat roof drain types. 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.

Or 12 drains required. Most flat roofs suffer from poor drain locations or drain levels that are high. The one challenge with flat roofing is ensuring proper drainage. The most critical of these issues is the flat roof drainage systems.

Main features flat roof drainage design guide first off the flat roof drainage design guide is an extremely basic direct and utilitarian design every single current trademark. Select number of roof drains and calculate the roof area sloped to each drain. Show down spout and location of discharge to ground surface which shall be at least 5 feet from foundations walls or to an approved drainage system. 50 000 4 400 11 36.

The flat roof drainage design guide can go up against different style that when nitty gritty right can ooze a cutting edge feel. The result is the number of drains needed. At page top and at left our photos show a low slope roof surrounded by a parapet. Of course the best designed flat roof has the correct amount of pitch to drain the water off naturally.

Drainage devices e g sizes elevations type of material inlet and outlet structures energy dissipators. Keep in mind all flat roofs have a slope of between five and 15 degrees to allow water to flow into drain systems such as eaves drainage holes or outlets. Some pipes are too small to handle the volume of the water. Size horizontal storm drainage piping.

Poor drainage can lead to serious issues with flat roofing from leaks to structural damage. Unless otherwise recommended by a geotechnical engineer lacrc. Size vertical storm drainage piping. Watch for clogs blockage at the roof drain or scupper.