Any experience with cellulose batts? (vs dense pack or mineral wool)
oldbungalow
| Posted in Green Products and Materials on
Hi, I realize batts don’t have quite the air sealing quality of dense pack, but aside from that, in a hybrid configuration (with foam air sealing to the exterior), would cellulose batts be a pretty good alternative to dense pack? To rockwool batts? There is a labor/equipment savings over stapling netting and pumping it in.
Here’s a link to one product, this is not an endorsement.
https://www.cmsgreen.com/insulation/ecocell-batts
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Hello KT,
I was hoping you would get some answers to your question, I’m also considering these ecocell batts as an alternative to dense pack cellulose, (assuming you mean dense pack cellulose?) wondering about real world experience installing, and how they compare to mineral wool batts. from what I have read and gathered here on GBA and other sites, seems like cellulose batts would have the same characteristics as dense pack cellulose as far as being a moisture buffer, and probably a bit better at reducing air flow than the mineral wool. What zone are you located in? (I'm zone 3) Do you plan on having any kind of air barrier/vapor control layer on the interior?
Zone 4, no barrier on interior other than paint and drywall. I suppose if it's densepack, there will be some kind of plastic/net on the interior but not sure the perm of plastic sheeting used for that application.
Very good answer from Dana Dorsett below! I will be investigating these cellulose batts, maybe I can get CMS to send me a sample. dense packed cellulose in my area seems to be nonexistent, everybody is just spray foaming... and I would rather do a friction fit mineral wool batt than wet sprayed anything.
Cheers
Your link does not work it just has a spinning wheel no info on this very unusual product.
You may want to consider damp sprayed cellulose generally wins the lowest installed cost per sqf war.
Walta
I just tried the link and it worked, maybe it's a regional product? Dunno. Yes damp sprayed is great but seems less and less available these days, must be a shfit towards something else. Also takes a long time to dry out. Thanks for commenting!
>"You may want to consider damp sprayed cellulose generally wins the lowest installed cost per sqf war."
Damp sprayed cellulose will often have shrinkage voids next to the studs when installed in wall cavities. See Armando Cobo's pictures in response #4 of this thread:
https://www.greenbuildingadvisor.com/question/how-much-for-damp-spray-cellulose
https://s3.amazonaws.com/greenbuildingadvisor.s3.tauntoncloud.com/app/uploads/2018/08/08102458/Wet%20Cellulose%20and%20Stud%201-700x934.jpg
https://s3.amazonaws.com/greenbuildingadvisor.s3.tauntoncloud.com/app/uploads/2018/08/08102457/Wet%20Cellulose%20and%20Stud%202-700x934.jpg
Voids using friction-fitted batts, are a function of installation quality- if the installer is meticulous about trimming & tucking it can be tighter than a damp-sprayed wall (but not tighter than a dense-packed wall, where the fibers follow the air flow during installation and clog incidental leaks.)
>"Zone 4, no barrier on interior other than paint and drywall. I suppose if it's densepack, there will be some kind of plastic/net on the interior but not sure the perm of plastic sheeting used for that application."
In Zone 4A/B an impermeable plastic sheeting layer would be more likely to create rather than avoid a moisture problem. In Zone 4C vapor barrier layers can be useful in some wall assemblies, but it depends on the sheathing and siding. In all Zone 4 cases using cellulose rather than rock wool provides some protection to the structural wood from heating season moisture drives, since the cellulose will share and redistribute the moisture burden without damage or loss of insulating function, as long as the interior humidity levels are reasonably well bounded. (Basically, don't humidify the indoors to 55-60% RH in winter- keep it under 40% RH during the coldest weeks.)
475 Performance Building Supply has a video on how to dense-pack behind their variable permeance Intello "smart" vapor retarders here:
https://foursevenfive.com/blog/video-intello-plus-with-dense-pack-cellulose/
That's a lot more expensive than blowing mesh, and not really buying you much (if anything) in most zone 4 wall assemblies.