Duct hanging question

[SCBO1]

Can retangular duct for heat and return supplies be stacked on top of each other and then hung from 1.5" hanger strap? First time I have seen this done and the concern is that the strap is not strong enough and that uni-strut should be used. Problem is I can not find information where you can double stack the duct? Looked in the SMACNA standard and viewed designs but all are single duct install designs.

pc1

 

[JBI]

Does the strap manufacturer have a specification/recommendation?

 

[mtlogcabin]

603.10 Supports.

Ducts shall be supported with approved hangers at intervals not exceeding 10 feet (3048 mm) or by other approved duct support systems designed in accordance with the International Building Code . Flexible and other factory-made ducts shall be supported in accordance with the manufacturer's installation instructions.

Look at the size and will the hangers and fasteners support the weight is the question.

Are the ducts internal insulation or external?

 

[SCBO1]

JBI, I will need to retrieve that information to be able to answer that question. But thats a start, not seeing the right amount of screws installed into the duct either, which makes me think I've got some yahoos doing the work and the old "they let us do this in bugtusle!"

pc1

 

[SCBO1]

mtlogcabin, internal insulated duct.

 

[Gregg Harris]

Can retangular duct for heat and return supplies be stacked on top of each other and then hung from 1.5" hanger strap? First time I have seen this done and the concern is that the strap is not strong enough and that uni-strut should be used. Problem is I can not find information where you can double stack the duct? Looked in the SMACNA standard and viewed designs but all are single duct install designs.pc1

Should not be an issue as long as the linear spacing is followed per duct dimension. It's strength is only as good as the fasteners "screws" used.