Bonfiglioli Insulation
nlbailey
| Posted in General Questions on
I asked this question over on Fine Homebuilding but thought it would be a good place to ask here too.
I am looking for a wall assembly for an addition / remodel and keep coming back to the Bonfiglioli wall assembly as a good choice.
The only thing I don’t understand is the wall depth for insulation. With 2×6 wall framing, foam strips and 1×3 furing strips that gives you 7.25” of depth. In the article (View PDF) it references R-30 with fiberglass insulation but as far as I am aware there isn’t R-30 available in that depth.
I know mineral wool can fit that cavity but the article specifies using fiberglass as the reason it is a lower cost per sq. ft. I also looked at higher r-value insulation that could be compressed but it still doesn’t result in r-30.
Am I missing something? Anyone have any insight into this?
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Replies
Just wanted to bump this post since it had issues posting initially.
I was looking into this wall assembly as well and came to the same conclusion. When I looked into R30 fiberglass more it seems like the denser R30 fiberglass, 7.25" thick, is readily available in other countries but not in the United States. I'm assuming US manufactures don't see much demand for it in the states?
There are high-density batts that are R30 and 8-1/4" thick:
https://www.homedepot.com/p/Knauf-Insulation-R-30-EcoBatt-Kraft-Faced-High-Density-Fiberglass-Insulation-Batt-8-1-4-in-x-23-in-x-48-in-8-Bags-691002/313646773
The manufacturer information is spectacularly unhelpful as to whether it can be compressed, and what happens to R-value when you do.
This chart is from a different manufacturer but I bet the results are similar, netting R-27.
In the product Q&A it says, "Some products will resist compression into framing cavities that will hinder installation and may deform drywall or other covering." But it gives no specifics.
I haven't used high-density fiberglass myself but having tried to push mineral wool into spaces not deep enough, I can see that it can be challenging.
Or you can put in two R15 batts
Good point, R15 batts seem to be 3.5", so you are actually less than the 7.25" cavity. I wonder why the R30 batts are larger.
The R15 fiberglass batts are "high density". My guess is there is not yet enough demand for the thicker batts to be higher r value to warrant the capital investment it would take to change over production lines.
The R-30 I linked to in post #3 above is high density.
True, but they don’t reach the same r value in the same thickness as two R15 batts. So maybe higher density, but not as high as the R15 batts?