Flat Roof Drainage System

The sketch at left common leak points at flat roof drainage systems.

Flat roof drainage system. Your building and location can help determine which drain will fit your roof needs. Of course the best designed flat roof has the correct amount of pitch to drain the water off naturally. Click to enlarge any image scupper drains become blocked by leaves or other debris through building drains upper right in the sketch become clogged internally and burst flooding the building or leaks occur around the drain itself where it penetrates the roof. It s also sometimes used in tandem with scuppers.

These drains are like the drain at the. In most cases a flat roof will pitch in a single direction where gutters can then catch the runoff to remove it. A flat roof may use interior drains to collect water from the centre of the roof. This kind of drainage system is most common on small flat roofs where water volume and buildup isn t extreme.

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. They are often positioned towards the center of the roof or the place where the slope of the roof allows water to collect. Scuppers internal drains gutters. Poor drainage can lead to serious issues with flat roofing from leaks to structural damage.

The one challenge with flat roofing is ensuring proper drainage. There are roof coating products available if there isn t enough slant or slope to accomplish this. The drainage pipes are placed under the roof and in the walls of the building. Each of these systems has its own pros and cons.

Although not commonly used anymore the eavestrough drainage system is a good option if you have an older large industrial or commercial flat roof. A residential roof collects water in the gutters and the. These ditches guide water toward the eavestroughs. A gravity drainage system on a flat roof differs from the gutter system you find on residential roofs in two key ways.

Drainage ditches are created in the roof in the lower insulated areas. Typically flat roof drainage systems fall into one of the following categories.