Flat Roof Rain Water Drainage

The calculations below are meant for drainage from flat roofs where water are expected to spread over the entire flat roof during rain.

Flat roof rain water drainage.

Other roof outlets include stainless steel rainwater outlets cast iron rainwater outlets flat roof drainage outlet solutions and brand specific aco roof outlets and caro roof outlets. Flat roofs have unique architectural characteristics that make them desirable in many situations. The drainage system of any roof can be located at the edge or in the middle of the roof. The roof drainage outlets and rainwater downpipes are calculated based on the design principles for gravity drainage systems established in ss525 2006 code of practice for drainage of roofs.

The main benefit of inner drains is that the system is hidden from view. Furthermore flat roofs with internal drainage are built to direct water to the central points of the structure with a concave shape the opposite of a pitched roof. When debris is allowed to collect around drains scuppers or in gutters then the roof is compromised. For a large roof it is recommended to have drains placed at multiple locations within the area of the roof.

No matter the type of drain system for a flat roof as long as it functions correctly this will extend the life of the roof. A light rain or drizzle for example remain remain on a flat roof for a short period of time. For larger flat roofs like those used for flats townhouses commercial buildings or schools it s common to have a drain placed inside the roof edge. 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.

Flat roof drainage falls into 2 main categories gravity drainage and syphonic drainage. Increasing the angle of a flat roof will always. They are ideal for climates that don t experience large quantities of rain and moisture. The roof is designed to have a gentle slope towards that drain from where the water is piped away from the walls and foundations.

Watch this video on explaining flat roof drains. Pooling water has adverse effects on a flat roof. Inner roof drains. Visit this page to know more.

Gutters are the most commonly used and most cost effective drainage solution for flat roofs. How water runs off a roof depends on the amount of rainfall and how quickly it needs to drain. Rainfall onto flat roofs needs to be correctly managed to protect the structure against ingress of water. A rooftop garden or additional outside living space are the top reasons people choose 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.