Ibc s secondary roof drainage requirement first was added in ibc 2009.
Secondary roof drain code requirements.
Part a d1 1 d notes that.
Once the number of required drains for the area is determined the size of the drain inserts and plumbing should be established.
The rationale for not requiring secondary drainage is that if positive drainage is provided that is adequate to drain the roof.
This is completed using a plumbing calculation.
See section 1107 for yourself.
Exception 1 of section 1511 1 states existing roofs do not have to meet the requirements of the code if positive drainage is provided.
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Where roof drains are required secondary emergency overflow roof drains or scuppers shall be provided where the roof perimeter construction.
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.
The minimum slope the code allows is in 12 in.
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.
The uniform plumbing code followed a similar path to incorporating secondary drainage requirements.
Secondary emergency roof drains or scuppers are required according to ipc to prevent a rainwater build up.
Prior to the 1994 upc the only mention of secondary roof drains is a listing of the materials to be utilized for over flow drains in the 1994 upc rainwater systems was included as appendix d to the code.
Roof system provides for positive drainage.
When a secondary roof drainage system is installed it shall discharge independent of the primary building storm system and shall terminate a minimum of 18 above grade in an area that will be visible to the people who occupy the building.
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.
This system shall be compliant with all federal state and local codes.
1511 1 roof assemblies and rooftop structures general.
