Box netting for rafter blow in insulation (where to buy?)
Looking for a source for box netting for blown-in insulation at the rafter level (now code compliant and one option for air permeable insulation in combination with a vapor diffusion port).
There are quite a few articles that mention the Dow Corning ProPink”High Performance Conditioned Attic System, see https://www2.owenscorning.com/literature/pdfs/hpca%20installation%20instructions.pdf and screenshot attached as image.
This older (but updated) GBA article discusses the system and specifically talks about the netting being good: https://www.greenbuildingadvisor.com/article/can-unvented-roof-assemblies-be-insulated-with-fiberglass
But I can’t find this sort of netting anywhere to purchase. Does anyone know if it really available?
I’m guessing the specific product might be only available through Dow Corning channels to their approved contractors … but are there any similar products available?
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Replies
James,
Are you dense packing trusses, or do you have rafters deep enough that the netting can run along the underside? I think the advantage of the Dow Corning system is dealing with the former, and that there are a number of options for the latter.
1948 2x4 rafters (with a few kickers down to joists). So effectively trusses. Trying to get deeper insulation without extending rafters.
There is generic insulation netting intended for use on vertical surfaces. Putting on a slope seems risky over the next 50 years.
15 seconds of Googling got me this link to the Dow Corning product.
https://www.monsma.com/Product/oc-propink-wall-fabric-9-2-x600-24-p-oci-741736
Will you be able to get the code min R value in the current rafter depth?
Walta
Yeah, issue is that these are 2x4 rafters (1948, effectively trusses), so nowhere near enough depth. Trying to figure out if can avoid solid rafter extensions/fur down (and lose fill insulation much less expensive than batts, as well as rafter spacing being non-standard). The box netting approach also puts insulation underneath the rafters, reducing thermal bridging.
I'm not worried about the air-permeable insulation on a sloped surface due to the vapor diffusion port, but I am worried about the physical permanence of this boxed netting system, since it seems to be held together with staples, as well as held onto the rafters with staples. Seems like a lot of weight to hold up!
Contacted Ownes Corning and they said,
"The High Performance Conditioned Attic System is no longer available through Owens Corning. While there are contractors who are trained in this system, we no longer have a directory. I would recommend reaching out to local Insulation Contractors directly about their ability to install that system."
So yeah, that explains why it isn't available :)