Roof Drainage Design

Secondary drainage shall be provided through the use of sidewall scuppers or internal roof drains.

Roof drainage design.

Secondary or emergency roof drainage is required wherever the buildup of water is detrimental to the roof structure. Hence this is by far the most common roof drainage situation. For most dwellings you ll find that gutters range in size from approximately 100mm diameter to 150mm diameter assuming gutters with a half round section profile and downpipes range from approximately 60mm diameter to 90mm diameter assuming circular downpipes. For larger roofs siphonic drainage systems should be installed.

Having sufficient drainage on a flat roof is vital. Inner drains are resistant to freezing but can require careful maintenance to prevent problems. 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. In either case the discharge shall be located so that it is readily visible by building occupants.

When designing a roof it is essential to pay close attention to where the drains are. Aco offers functional solutions which are specially designed for flat roof areas and which ensure the water is drained effectively. In addition to the primary roof drains there will also be overflow drains which are used for redundancy and sized in the same manner. On many occasions drains are too high and water cannot flow off.

These drains are distinguished by having higher rims. One gully can drain at least 150 m2. The main benefit of inner drains is that the system is hidden from view.