Secondary Roof Drainage Requirements

Such an installation would be sufficient to address a building that was 75 feet wide with drains located 25 feet from either edge.

Secondary roof drainage requirements.

It s very short and to the point. 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. The general approach to calculating roof drainage requirements includes the design point of anticipated maximum rainfall intensity. Once the number of required drains for the area is determined the size of the drain inserts and plumbing should be established.

Secondary drainage was not required with ibc s previous editions. Secondary emergency roof drains or scuppers are required according to ipc to prevent a rainwater build up. See section 1107 for yourself. 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.

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. Using ibc 2009 or ibc 2012 it could be inter preted the addition of secondary drainage may be required during reroofing this was not the intent of the 2009 code change. If they are used for secondary drainage then they should be a minimum of 2 inches above the roof level and a maximum of 4 inches above the roof level. Secondary drainage secondary or emergency roof drainage is required wherever the buildup of water is detrimental to the roof structure.

Firstly there is an explanation in the above referenced section for where and why a secondary roof drainage system must be provided. Secondary emergency roof drain systems shall be sized in accordance with section 1106 based on the rainfall rate for which the primary system is sized. For an allowable ponding depth of 9 inches with a scupper height 3 inches above the edge of the roof and a roof pitch of 2 the maximum value for d would be 25 feet. Once the required rainfall data has been determined the primary and secondary roof drainage system must be sized in accordance with.

This is completed using a plumbing calculation. In either case the discharge shall be located so that it is readily visible by building occupants.