Internal Gutter Flat Roof

A gravity drainage system on a flat roof differs from the gutter system you find on residential roofs in two key ways.

Internal gutter flat roof.

Built in gutters also referred to as box gutters are considered a concealed roof drainage system. Gutters can also be installed to work in tandem with a scupper system. Scuppers are holes often with spouts along the wall at the edge of a roof that allow water to shoot off the roof. For this reason internal drains can be placed throughout the interior of the field which allows for better use of roof slope to encourage drainage while maintaining a flat roof.

Internal or within roof area gutters also known as box gutters can cause significant inconvenience damage and repair cost if water from the gutter gets into the building structure below. A flat roof may use interior drains to collect water from the centre of the roof. These drains are like the drain at the bottom of your shower except that the roof drain has a larger strainer to protect it from debris. Unfortunately being unseen often results in neglect.

Because water pouring off a building is hazardous they often empty into the gutter system where the water can be safely drained away. With flat roofs it is a simple matter of calculating area since the true roof area is equal to plan area. In reality a flat roof isn t fully level and flat roofs built for gutters should direct water to one or more sides where the gutters are installed. The maximum accumulation of rainfall occurs when it falls perpendicular to the roof plane.

Some commercial roofs have drains like the drain in a shower. Gutters are often a viable option for flat roofs directing water on the outside of the structure to downspouts. The area of roof contributing runoff to each gutter and downspout should be determined. Scuppers are often used for flat roofed buildings along with a gutter system.

Since they are not readily visible they typically don t alter the historic character of buildings and don t detract from or conceal decorative cornice details. Here are the three most common types of drainage systems for flat roofs. Internal drains this system is made up of drains that are usually located near the center of the property which are attached to an internal network of pipes that drain the water away through the roof keeping the water far away from the walls and foundation.