A close-up view of the pumice crete blocks with an “R” value of 2.5 per inch, meaning a total “R” value of roughly 30 for 12″ walls. These stack able blocks are made from a pumice-crete and cement mixture. Pumice as you might know is a volcanic based rock which is light and has an airy, high insulation value. Specifically it is a hardened volcanic froth which creates a small pebbly, very light reddish rock that is plentiful in areas of the Southwest.
The manufacturer located in the town of Belen, New Mexico who patented this block, had a small lot where quantities of the blocks where hand made. Each block only weighs about 20 lbs, much lighter than an adobe block. And due to the channeled design, the pumice-crete blocks stack well when staggered as in any brick laying method. Once the walls or structural aspects are risen to the desired height, a pumice-cement slurry is poured inside the three channels. The result is a solid pumice wall without the form work necessary for a poured pumice-crete wall.
The manufacturer of these blocks was happy to use this large home as a showcase for his product, so worked closely with us and our client. We used this material on one other occasion with good success, but are not certain the blocks are still being manufactured as of this writing.