Can cellulose insulation be used on a foundation wall?
rocketconstruction
| Posted in Green Building Techniques on
We are renovating a basement with a cider-block wall — some above grade, some below. We put a watertight membrane on the outside and were planning on putting foam panels against the wall, taped, and then shoot cellulose to add insulation. A new cellulose subcontractor tells me that he never does that, and that we should only use rockwool. It seems to me that the foam will prevent condensation.Any thoughts?
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Replies
See Martin's article on insulating a basement. You cannot use cellulose or rock wool.
https://www.greenbuildingadvisor.com/blogs/dept/musings/how-insulate-basement-wall
Thanks Steve,
I acknowledge that you can't use it directly against the concrete but that is not what I'm proposing.
Thanks, but in Martin's article it mentions that you cant go direct with cellulose or rockwool, but if i break the thermal bridge with a layer of foam insulation , properly taped and sealed, and then in the 2x4 cavity fill it with celluloce. I am thinking that that way the thermal bridge is broken and the celluloce is protected from moiture and condensation.
It's not a condensation issue (assuming you have a sufficient ratio of foam-R for your climate), but rather what happens with even a minor flood- even if it were only an couple of inches of water on the basement floor.
With cellulose water would wick all the way up to the top of the stud bays, and you'd have to replace 100% of the wallboard & insulation to repair it.
If it's rock wool or fiberglass you'd only have to remover & replace the wall & insulation from about a foot or so above the high water mark- everything above that would usually be dry enough to leave in place, if you give it a reasonable drying period before closing it back in.
In basements with no flood history and low flood risk rock wool or fiberglass would be fine.
Putting an inch of EPS under the bottom plate of the studwalls as a thermal & capillary break from the slab is also useful. It keeps the bottom of the bottom plate above the summertime air's dew point, and severely limits how fast water can wick from a damp slab into the wood.
William,
Dana gave you good advice. It's not unusual for a basement to get flooded. You don't want cellulose in that location.
The best way to go is 100% rigid foam. If you want to switch to fluffy insulation after installing an adequate amount of rigid foam, use mineral wool. If you don't want to use mineral wool for some reason, use fiberglass. But in no case should you consider cellulose.
Thanks guys, very much appreciated.
Would something like Ecocell cellulose blankets be OK to use in a basement? https://cmsgreen.com/insulation/ecocell-blankets
"ECOCELL meets the required ASTM testing for moisture absorption. If ECOCELL blankets get wet, they dry out more quickly than
other insulation materials."
"ECOCELL insulation contains an EPA registered fungicide that resists the growth of mold even in conditions favorable to mold growth."
UL Report: https://cmsgreen.com/sites/default/files/ulex.r26300.pdf
It's treated with Boric Acid & Sodium PolyBorate, which seems to be effective even over the long-term at eliminating fungal growth: https://www.semanticscholar.org/paper/Sodium-Polyborate-Based-Additives-on-Recycled-Kill-Herrera/e28f1ee140e690c758b66da6a74a88e78472ca2c
Thoughts?