Types of duct insulation available
jonny_h
| Posted in Green Products and Materials on
When talking about building enclosure insulation, there’s so many choices — fiberglass, mineral wool, cellulose, half a dozen types of foam, wood fiber, cork, actual sheep wool, etc…. But, when it comes to insulating ductwork, it seems like there’s (maybe) three choices: R-6 to R-8 fiberglass wrap, the bubblewrap stuff that’s better as packing material, and Armaflex rubber duct wrap (if you can find it). Where are the alternate options when you want more R-value than what these products offer, or don’t want to use fiberglass from a materials perspective?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
The smart move is to keep the duct work and equipment inside the conditioned space then insulating the ducts becomes almost irrelevant.
Walta
Almost irrelevant -- but some things (like HRV intake / exhaust ducting) would still need to be insulated. But, I fully agree with keeping things inside the conditioned area as much as possible.
Per code, you need to sealed and insulate your ducts, with R8 in vented spaces, or R6 in unvented spaces. To avoid condensation in ducts in ventilated spaces for CZ1-3, the codes allows to double wrap the ducts with R13 min. (R8+R6). A good option is to encapsulate ducts in ventilated spaces with 2" ccSPF, and then pilling up CZ required insulation.
Check the Building America Solution Center's details for almost every situation: https://basc.pnnl.gov/search?keywords=insulating+ducts
I need to add that you can use duct board or phenolic duct (closed-cell rigid foam boards).
Could you run a continuous soffit with centering baffles around the rigid/semirigid ductwork, and dump blown-in insulation around that?
Or does insulating cold ductwork require something air & water-impervious like foam to avoid condensation?