Well done Leibler. If you cut the bottom of a wall cavity filled with Perlite you will find it flowing everywhere but up! And, it is darn hard to put back too.

Hi Leibler;

You had mentioned Perlite to me once before and i hope to visit their montreal plant tomorrow - turns out, it's about 5 klicks from my house!

They sell it in 114 liter bags (4 cu. ft.) I don't know what a bag will weigh, nor the price - should know more tomorrow.

Thanks,

Rob.

Rob,
    Perlite comes in different densities for different uses. The grade you want is what is typically used to fill CMU walls and should weigh under 30 pounds per bag.  This is the type and grade Bagerboiler commented about.