Secondary Roof Drainage Design

In many cases early structures were designed primarily as a shelter from the rain their very purpose was to redirect rainfall and maintain a particular area.

Secondary roof drainage design.

P 1503 4 roof drainage. Roof collapses are prevented if primary and secondary drainage systems are designed properly. Secondary emergency roof drains or scuppers are required according to ipc to prevent a rainwater build up. Secondary drainage shall be provided through the use of sidewall scuppers or internal roof drains.

From the very dawn of building construction it has been necessary to incorporate some method of gathering and discharging rainwater from the roof of a structure. Adequate drainage is an important component of a properly installed roof so installing the correct size of drains is essential. There are 3000 roof collapses a year in the. In either case the discharge shall be located so that it is readily visible by building occupants.

Once the required rainfall data has been determined the primary and secondary roof drainage system must be sized in accordance with. Ponding instability is avoided. Roof drainage is one of the fundamental considerations of building design. Considering the damage water can do when allowed to pond on roofs and overflow from gutters it is clear that ignoring roof drainage issues can lead to urgent problems.

Better to design appropriate drainage assemblies and address incipient concerns now than. Firstly there is an explanation in the above referenced section for where and why a secondary roof drainage system must be provided. See section 1107 for yourself. It s very short and to the point.

P 1503 4 1 secondary emergency overflow drains or scuppers. Roof drainage systems tend to be given little attention until they fail. Scuppers shall be sized to prevent the depth of ponding water from exceeding that for which the roof was designed as determined by section 1101 7 scuppers shall have an opening dimension of not less than 4 inches 102 mm. Following these four steps you can successfully specify the correct size of horizontal and vertical drains required for any roof.

Otherwise the system will not adhere to the above referenced principle. Why is roof drainage so important. Generally the roof system is more durable. The secondary roof drains can be of two types roof drains with an independent piping system or roof drains that combine with the primary roof drainage piping which will require an increase in piping size.

Example of a primary secondary thru wall drainage to downspout courtesy of ernie s gutter. Design and installation of roof drainage systems shall comply with section 1503 of this code and sections 1106 and 1108 as applicable of the international plumbing code. The drainage system shall incorporate adequate cleanouts placed in a manner that the drainage system may be readily cleaned.