roof top units forced air

[bptp32]

I have a 20,000 sq foot mercantile occupancy, type II-B construction, non separated uses. 2010 Building Code of NYS.Fully sprinklered per NFPA 13. The structure has two roof top units supplying forced air heat to the mercantile areas including the offices, display room, bathrooms, break rooms. There are no ceilings shown on the plans, just 16' clear space from finish floor to underside of bar joists. The RTU's are not ducted to the rooms or to the interior areas. Each unit has one diffuser at the roof area to supply heat to the total space. Fisrt, are ducts required to provide warm air to the individual rooms. second, if this is a forced air system will all of the exposed construction items need to be plenum rated i.e wiring, plumbing etc. Thanks for the assistance

 

[mtlogcabin]

First, are ducts required to provide warm air to the individual rooms. I do not see how they will meet the requirements of IBC 1203 and 1204 or Chapter 4 of the IMC without duct-work.



second, if this is a forced air system will all of the exposed construction items need to be plenum rated i.e wiring, plumbing etc. NO see the definition of a plenum.

 

[Frank]

If it is open ceiling and the partitions do not extend to the underside of the roof deck, then it can be done without ductwork and is not a plenum. Once they close off an office etc with a ceiling or walls to deck then ductwork would be needed.

 

[Gregg Harris]

I would agree if open design a concentric dropped down from the unit is all that is needed. I do not see how the bathrooms will comply with this design.