PDA

View Full Version : Rooftop Ductwork


Metal Militia
03-10-2011, 10:47 AM
Anyone ever clad externally insulated rooftop duct?

Any ideas pictures or tips would help.

Thanks
Metal Militia
03-10-2011, 10:50 AM
Sorry should have said...specification calls for galvanized metal cladding.
acwizard
03-10-2011, 12:48 PM
In other words , no liner accepted in air stream, typical of a hospital,operating room etc. This would be a double duct construction where the insulation is wrapped around the inner duct and the outer duct protects the insulation. Very expensive and do not forget about the added weight.
acwizard
03-10-2011, 12:51 PM
Also insulation board is pin welded to outside of inner duct. A light gauge galv could be screwed over this insulation board. I think you should have engineer clarify with a detail drawing of exactly what they want.
Metal Militia
03-10-2011, 07:03 PM
Yes, expense and weight have allready been accounted for and the engineer is open to suggestion, basically he has asked our thoughts on the best ways to accomplish the task. Im kinda thinking about a 1" standing seam....but not sure
Lash
03-10-2011, 07:10 PM
I did a job in double wall TDC, but we just made the inner duct regular sheet instead of perforated. Outter skin was just 1 ga. lighter metal, 2" insulation between. It was actually cheaper than wraping and clading the duct... which never seems to hold up anyway. And it looked better IMO.
VTP99
03-10-2011, 07:16 PM
What about insulation wrapped in EPDM ?
Metal Militia
03-10-2011, 07:17 PM
Lash....so basically, internally lined your outer duct and then used flatstock to line the inside? Sounds like a good idea.
Metal Militia
03-10-2011, 07:19 PM
VTP99.... Im not familiar with EDPM
genduct
03-10-2011, 07:20 PM
Better consider a closed cell product, almost impossible to maintain the vapor barrier.
better look to an insulation distributor who can suggest the fabric and mastic to try to seal it all up
Lash
03-10-2011, 07:22 PM
Lash....so basically, internally lined your outer duct and then used flatstock to line the inside? Sounds like a good idea.

You got it.
VTP99
03-10-2011, 07:27 PM
VTP99.... Im not familiar with EDPM

Sorry spelling is EPDM ( ethylene propylene diene monomer ) or synthetic rubber. Widely used on flat roof tops.
Metal Militia
03-10-2011, 08:05 PM
I am familiar with EPDM....The engineer will not accept
VTP99
03-10-2011, 08:08 PM
I am familiar with EPDM....The engineer will not accept
For what reason ?
Metal Militia
03-10-2011, 09:03 PM
In his expirience birds will pick at any kind of soft cladding...
VTP99
03-10-2011, 09:10 PM
In his expirience birds will pick at any kind of soft cladding...

That's crazy ! Roofs would be leaking all over the place. ::DD:
Metal Militia
03-10-2011, 09:22 PM
You could not be more correct..I guess thats why he makes the big bucks....lol
VTP99
03-10-2011, 09:27 PM
I have seen this done more then once with no problems. It also helps to seal the duct from leaks. Big plus there. Never seen a bird problem and i have been on a lot of rubber roofs. Just my :.02:
acwizard
03-10-2011, 11:30 PM
If the engineer would permit, check out Polyguard.It is an excellent way to insulate on the exterior side of outdoor ductwork.
Industrial Air
03-15-2011, 12:36 PM
Anyone ever clad externally insulated rooftop duct?

Any ideas pictures or tips would help.

Thanks

30 g. stainless. cross broke w/ standing seams, very easy, or if it's not installed already, you can make lined duct with the ID dimesnion large enough to enclose the air carrying duct, similar to k-27 acoutic duct but solid metal instead of perforated