Air Krete?

[guitarsanddrums]

Anyone encountered or used this product? 

I was looking for alternatives to closed cell spray foam that would provide both insulation (r value) and air sealing abilities and came across air krete. A downside is compared to closed cell spray foam is it's not a vapor/moisture barrier.  I know closed cell spray foam isn't widely regarded for reducing noise transmission and could even increase it by coupling. Even if primary goal is not for soundproofing, i'd hate to make things worse sound transmission wise by using wrong product.

There are some claims relating to sound "barrier" abilities which seem a little questionable. There is this document that's says assembly with it tested as STC 44. http://www.airkrete.com/testResults_files/SOUNDPROOFTEST%20%282%29.pdf   However,  unless i am misreading it, i don't see a true before and after test from same assembly or two identical assemblies with the addition of the product  as only change in one. If it was stc 43 prior to the insulation added, its not very impressive but if it was stc 34 prior then that would be a very noticeable improvement.

I'd guess the air-sealing ability may be a significant thing if there are cracks where air can pass-through. Sealing those will certainly be important step for soundproofing (and weatherization) which could provide reduction of sound transmission but other methods of sealing could be just as or more effective. Maybe i'm being overly skeptical. 

Any other thoughts? 

[Randy S]

I have heard of it but never used it in my designs. Based on the test data it looks like the airkrete added about 100 +/- lbs to the assembly. Which basically came close to doubling the mass therefore a 5 db loss would be about as best you would see over a standard 5/8" sheetrock wall with insulation.

The problem I see is the increase of a coupled system and the cost and labor over simply adding another of 5/8" drywall on each side of an insulated wall.

And I would really like to see the effects of this product in a wall design that already is at 8lbs per sqft. or greater.
I would assume a little to none.

Randy S.