Tearing kraft facing off 2,000 sq ft of R15 Batts
jwolfe1
| Posted in General Questions on
It has been awhile since I worked with faced fiberglass batt insulation and when I did I never tore the kraft facing off. How hard and annoying is it to tear the kraft facing off a large number of batts, like ~2,000 sq ft worth of batts? Unfaced batts are not available until April 9th and cost $1.04 per sq ft. Kraft faced batts are in stock now in the amount I need and are only 0.63 per sq ft. This is for R15 batts. I’m doing two layers of R15 to get to R30 in my walls and using Certainteed Membrain. Is tearing the the kraft facing off this much insulation not worth the effort?
Thanks.
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To be clear, you have a ~7 inch wall?
I would have no qualms stacking kraft faced batts.
Are you using the Membrain as an air barrier, vapor retarder, or both?
Thanks Patrick, The wall is actually 7.25 inches. I'm doing a Bonfiglioli wall. The Membrain will be both the air barrier and vapor retarder. I feel like the kraft paper will make a good installation more difficult and three vapor retarders doesn't seem like a great idea.
> three vapor retarders doesn't seem like a great idea.
Why? What's your specific concern? If you are viewing the Membrain as your primary vapor control layer, what risk do you see from the kraft mid-bay?
If you need Membrain inboard, you're likely in a cooler climate. So if the Membrain does its job, any kraft beyond it has no work to do. There is no vapor for it to mediate. The kraft becomes a non-combatant, if you will.
Kraft paper itself is a "smart" membrane. You may be able to save yourself some trouble and expense by omitting the membrain and simply keeping the Kraft.
Here's a bit more on the topic by one of the manufacturers.
https://www2.owenscorning.com/literature/pdfs/10017860%20Moisture%20Control%20Perform%20Kraft-Asphalt%20Facing%20Tech%20Bulletin.pdf
I'd try calling around to a few other suppliers to try to find unfaced batts, at least to use for the inner layer. I do think that extra kraft paper layer, while not a problem as an additional vapor retarder, may make it difficult to get the batts installed without voids. The kraft faced batts tend to have a little more "attitude" than the unfaced batts, and in this case I think that means you'll find them more difficult to get installed into an even layer without gaps and voids between the inner and outer layers of batts.
I think removing the facer will be a pain. That kraft facer is super thin, and tears pretty easily, so I think trying to remove that much of it is going to be a frustrating experience. I'd gladly pay a little extra to avoid having to deal with that, although I can understand a long lead time being a problem.
Bill