Part a d1 1 d notes that.
Secondary roof drain code requirements.
Secondary drainage was not required with ibc s previous editions.
1511 1 roof assemblies and rooftop structures general.
Ibc s secondary roof drainage requirement first was added in ibc 2009.
The minimum slope the code allows is in 12 in.
Where roof drains are required secondary emergency overflow roof drains or scuppers shall be provided where the roof perimeter construction.
See section 1107 for yourself.
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.
Exception 1 of section 1511 1 states existing roofs do not have to meet the requirements of the code if positive drainage is provided.
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.
It s very short and to the point.
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 rationale for not requiring secondary drainage is that if positive drainage is provided that is adequate to drain the roof.
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.
Firstly there is an explanation in the above referenced section for where and why a secondary roof drainage system must be provided.
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.
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.
We would like to show you a description here but the site won t allow us.
This is completed using a plumbing calculation.
Once the number of required drains for the area is determined the size of the drain inserts and plumbing should be established.
Roof system provides for positive drainage.
