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Duct height above roof-like structure

t.moon.04

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Joined
Dec 1, 2020
Messages
4
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Hi all, I have a client asking about running a duct over a pre-engineered canopy structure (specifically the product is Extrudeck, they want to run a duct between the top pf the canopy and the structural cables). They are asking me about mounting requirements - I know SMACNA standard states an 8" clearance between top of "roof" and bottom of duct but they want to run it lower. I've looked through IMC and IBC but can't find anything about this and I'm not totally sure this would count as a roof anyway. Anyone have any idea if mounting lower would go against code? Thanks
 
It needs to be higher than water can pond on the roof, and should be higher then snow can build up, in order to reduce the chances of leaks.
 
The IMC specifically references SMACNA throughout section 603 for duct construction and support, so if it is considered a roof, the SMACNA standard would apply, primarily for the reasons stated by Paul plus for roof maintenance.
 
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