hanging duct from steel corrugated roof deck

[John Bosyj]

I commonly see the upper attachment for duct hangers to be screwed to the underside of the steel roof deck w/o a concrete overlay I do not see this detail in SMACNA. Is it permitted to hang ductwork from a steel corrugated roof deck or should the duct be supported from the open web steel joist(owsj)? Is there a detail in SMACNA or code for screwing the upper attachment to the deck if permitted?

 

[quark]

I don't know about codes (in fact, I never thought that this needs a code) but we do it regularly. If time doesn't permit to hang supports before concreting, we use anchor fasteners (fixing at troughs of corrugated sheet so that you have maximum depth concrete).

 

[DrRTU]

SMACNA 3rd addition 2005 HVAC Duct Construction Standards has an upper attachments figure 5-2 but you will need a detail / design information of point loading of the deck and transfer to the BJ or other structure. A few of the GCs, structural engineers or deck mfgs prohibit this application.

 

[lukaiENG]

The structural engineer and roofing provider will have recommendations on this.
They will give you restrictions on spacing, loading as well as connection detail. They normally want the connections in the 'valley' between the ridges