Box Gutter Overflow Design

A rainhead or sump is a container located between the gutter and downpipe that aids the flow of water away from the roof.

Box gutter overflow design.

Holes through the splash guard and the gutter. However a wider overflow may increase the length of the sump. The box gutter depth and the sump length are influenced by the size of the overflow. A box gutter is defined as a graded channel generally of a rectangular shape for the conveyance of rainwater within the building footprint including adjacent to a wall or parapet.

Sump with a side overflow device. Overflow devices need to discharge to the atmosphere in such a way as to prevent damage to buildings and property. Rainheads are an essential design element for buildings where internal box or trough gutters are used. A wider overflow needs less depth of overflow hence the box gutter depth will also be reduced.

Making the box gutter wider will also reduce the box gutter depth. This is very important so that water will overflow externally to the building rather than flood into the roof cavity. There will also be an overflow facility on the side or the end. The hydraulic capacity of an overflow device shall be not less than the design flow for the associated gutter outlet.

Failing to install appropriately designed box gutters and correctly sized and positioned overflow devices can lead to serious damage to buildings and contents especially in shed and flat house roof designs often resulting in hefty insurance claims which are a total burden. The hydraulic capacity of the overflow device must be no less than the design flow for the associated box gutter outlet. To use the gdo calculator enter information about the location roof design and types of overflow measures. Overflow provisions rain shadow roof slopes how to find rainfall intensity how to calculate the area of any catchment how to find the hydraulic grade of charged pipes how to design box gutters using the code how to use the extra features of the dp calculator box gutters allowable width slope length other plumbing codes how to exceed the.

Drill rivet holes for the gutter splash guard. A good box gutter design will have falls along its length together with sumps to collect water before it is fed into large downpipes.