Get Overflow Roof Drain Details

On sloping roofs, drains should be located in the valleys at a distance no greater than 50 feet from each end of the valleys. Weir should be flush with the valley roof surface, not recessed. On large roof areas, drains should not be spaced at a distance greater than 200 feet.

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. Still, the function of the two drains is the same. Water falls on the roof, and gravity draws it into the drain and down the pipes.

The water from the roof drips into the gutter system, which is a long piece of material that is installed along the edge of the roofline. The water will then flow through the gutter and then make its way to the downspout where it will then absorb into the ground.

Where roof drains are required, secondary (emergency overflow) roof drains or scuppers shall be provided where the roof perimeter construction extends above the roof in such a manner that water will be entrapped if the primary drains allow buildup for any reason.

Similar to the way the drain in your shower works, internal roof drains also contain plumbing that runs inside the building to divert water. A system of pipes is installed under the roof.

Downspouts: This roof drainage system is very similar to a gutter and is also called a roof drain leader. It works in conjunction with a scupper by carrying the water to the ground. This usually comes in the form of a pipe attached to the side of the building.

This section addresses such concerns by requiring overflow drains or overflow scuppers for those roofs that do not drain over the roof edges. Although the required roof drains must be located at the low points of the roof, the overflow drain inlets need to be located 2 inches (51 mm) vertically above the low points.