Slanted Roof Drainage

The one challenge with flat roofing is ensuring proper drainage.

Slanted roof drainage. In its simplest form the civil law rule says that landowners are strictly liable for altering the natural drainage of surface water. The rule thus is the exact opposite of the common enemy rule. A siphonic roof drain utilizes siphoning as a drainage mechanism resulting in drainage that is faster than that on any other type of roof drain. When you don t utilize the proper drainage solutions water will quickly pool on your roof and put unnecessary stress on your building s foundational support.

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. The minimum pitch for a roof is 1 4 12 which translates to 1 4 inch rise to 12 inches of run. For a large roof it is recommended to have drains placed at multiple locations within the area of the roof. Most flat roofs aren t exactly level.

To use scuppers as a flat roof drainage system the roof must have a parapet or perimeter wall surrounding it. The green roof solutions drainage conduit is a stainless steel channel for use with the aggredrain system. The channel is designed to be laid end to end and terminates either in the ballasted unplanted roof area or adjacent to the grs. Install the posts for the pitched roof.

Adding a roof can create drainage problems if the roof pitch is too shallow. The drainage system of any roof can be located at the edge or in the middle of the roof. Increasing the angle of a flat roof will always increase the speed of water movement across the surface. It pounds down on all roofs flat and slanted but if you have a flat roof it has nowhere to go.

The 6 slotted triangle shape is used beneath the aggredrain layer and allows for water to flow freely. In fact a roof is considered to be flat if its slope is no more than 10. Landowners have no right to alter drainage and they have the right not to be injured by others altering the drainage. The civil law rule.

That s why having a strong drainage solution in place is so important. Commonly used on flat commercial roofs siphonic drains allow for a minimal number of drains and all of the drains can be connected to a single leader. It must be adjusted so that the roof slopes gently towards the scuppers to drain away from the structure. The first step begins with digging holes into the ground for installing the posts.