Perlite Insulated Floor

I rounded up all the woven poly bags and pleaded with Diane, the neighbor that has horses, and began to transfer the perlite to the bags and place them in the dug out floor space. I found the larger sacks(23"x39") to be better than the common "sand bag" size(14x26). There I tamped them down, which was pretty easy. The perlite stays a little squishy but after filling the gaps between the bags and laying down the first layer of gravel things were satisfyingly solid. Subsequent tamped layers of damp,clayey soil and CR8 (crusher run) sharp gravel made things very sound.

A visit to the Perlite Factory

We are going to try Perlite as an insulator in a slightly below grade floor. I looked around here in DC and had marginal luck finding perlite or information about it. Somehow I found the Pennsylvania Perlite company and they answered all my questions. They have a plant in York, PA which is just under 100 miles from here so I rented a Uhaul trailer and went up. They can regulate the density of the product by varying the heat used to "pop" the raw material which comes from out west. I decided to use a density or around 7 to 8 lbs per cubic foot. It is called block fill and is used to insulate concrete block walls by filling the cavities. Ron, the site manager, told me that perlite is used in almost everything from paint to hand cleaners. I took some samples of different products. On the way back I found an oriental grocery store and bought sticky rice flour to try out lime/sticky rice plaster. Apparently it was used in the Great Wall and recently some scientists studied it to see what the reaction is that makes it harder and more impermeable. Near as I can tell the rice soup affects crystal formation in the lime. I am also trying some pre-popped perlite with lime putty to see if has any pozzolanic properties.