Does anyone know anything about Air Krete?

Aircrete is a name for autoclaved aerated concrete (AAC) block. Much used in Europe over the last sixty years or so, especially in Germany. Has been marketed in the US as Hebel block but never achieved major market penetration. http://www.understanding-cement.com/autoclaved-aerated-concrete.html

No, no. It's a spray foam type of insulation only it is not nearly as expansive and it is made with a cementitious chemical combination. It is like a foamed concrete with the consistency of shaving cream. It is fire proof and has an r-value of about 4 per inch www.airkrete.com. It's very good for those historic structures where you have a lot of boogie-woogie in the anular cavities that you need to fill but don't want to blow out the plaster. It looks really awesome, but the last time I priced it it was about twice the cost of densepacked cellulose. One other thing to note is that after it dries you can crush it to dust in your hands, so it needs to go somewhere where it will be protected if not undistrurbed.

C.

I have a friend that just recently installed the product in their walls a couple of months ago. They choose the product over cellulose because they still have the old knob and tube wiring and did not want to go through the expense of rewiring the entire house. So at least the installer claims it can be installed with the old wiring because of its fire rating.

All in all they are satisfied so far. And as Chris said, it does need to be in an enclosed cavity because we found some that was forced through some holes and it just crumbled in our hands.