Flat Roof Rainwater Drainage

Which type of rainwater outlet can prove beneficial to the design and performance of roof drainage and ultimately the building.

Flat roof rainwater drainage. Roof rainwater outlets are designed to provide effective drainage of rainwater on flat roofs. Flat roof drainage flat roofing comes with many benefits but it needs to have the correct drainage systems installed to ensure that water is removed effectively and doesn t collect on the surface. For flat roof drainage where you place your drains scuppers and the final material of the roofing is more important. The main benefit of inner drains is that the system is hidden from view.

Syphonic drainage was developed and first used in scandinavia in the earlier 1970 s and first used in the uk in the 1980 s. Ss525 2006 code of practice for drainage of roofs. Gutters are the most commonly used and most cost effective drainage solution for flat roofs. Inner roof drains are used on flat roofs and include a low section or channel that collects water and feeds it into a concealed drain that leads to an underground drainage system.

Inner drains are resistant to freezing but can require careful maintenance to prevent problems. To keep damage like leaks from occurring water should not stand on a flat roof for more than 48 hours. Flat roof drainage falls into 2 main categories gravity drainage and syphonic drainage. After 48 hours following a rain any roof which still has standing water is known as a ponding roof.

Since it s installed underneath the flat roof this drainage solution is typically used only with new roofs. First measurements of the roof are taken. Of course the best designed flat roof has the correct amount of pitch to drain the water off naturally. In this section we ve included a range of flat roof drainage options parts and accessories to suit your latest professional or diy projects.

The calculations below are meant for drainage from flat roofs where water are expected to spread over the entire flat roof during rain. They catch rainwater as it rolls off the edge of the roof and divert the water into a downspout that dispenses it a safe distance from the foundation of the building. The most critical of these issues is the flat roof drainage systems. The flat roof must have sufficient slope to allow water to flow towards the roof outlets.

Pvc roof outlets are most commonly used in conjunction with flat roofs that are manufactured from synthetic membranes whilst tpe roof outlets are used in conjunction with flat roofs made from fibreglass and bitumen. The angle is not significant enough to prevent water from pooling on the surface.