rockwool – anyone with a guess about specs not given for R value of Safe and Sound and STC value for Comfortbatt
rcke2
| Posted in Green Products and Materials on
Have yet to get a reply from Rockwool company…..but curious if anyone ever determined a reasonable if not perfect R value for their Safe and Sound insulation and an STC rating for their Comfortbatt.
I have a situation in one wall where I (owner/builder) could possibly use them in combination (layered) but would feel more confident moving forward if I had some way of dialing in a trade off
thanks!
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Is this thread useful? https://www.greenbuildingadvisor.com/question/interior-walls-mineral-wool-r-value-marked-or-sound-attenuation-fire-blanket
Wrt sound attenuation, both cellulose and rock wool work well, but everything I've read here and elsewhere regarding STC suggests that it is the overall assembly that matters. I.e., it's really easy to construct a room where the sound bypasses the nice insulation put in for sound attenuation.
1910duplex : thanks for the link - but i think that gives me more comparisons to make and lots of guessing...
Andrew C : thanks, and yes I have learned the same so far...in my case it is a small section of knee wall which i should be able to seal a full perimeter etc
Still, i have both products and willing to trim/thin/cut/shape to get what i need - just want to use the products effectively and want to understand what STC and R-value i get from each
The safe and sound product is the same as the normal mineral wool insulation in terms of R value per inch, safe and sound is just a little thinner so that it doesn't contact the wall surface on both sides of the wall. Normal mineral wool is R15 at 3.5 inches, the safe and sound variant is typically 3 inches thick, which will be about R12.8 or so. They can provide a letter stating the R value of the safe and sound version of their product if you need that info to satisfy an inspector.
I don't think there is a formal spec for an STC value of the "regular" version of mineral wool, at least I've never seen that info anywhere. I would expect it to perform similarly IF you maintain the small air gap on one side so that it's not contacting the wall surface on both sides of the wall (the air gap helps to reduced conducted sound a little). My GUESS based on my own experience with both products (actually the Owens Corning variant, which is pretty much the same thing) is that there isn't all that much difference in sound blocking performance between the safe and sound and the regular mineral wool products. The sound transmission in a wall of that type is dominated by the "acoustic bridging" (my term :-) of the studs.
Bill
Thanks Bill - I think that gets me where i needed to be. I would not enjoy thinking that i had done something clever only to learn when it was too late that i actually did something opposite of optimal.
Much appreciated