Alternatives to adobe
Pumice-crete, straw bales and light straw clay offer options beyond traditional but costly construction method
In many parts of the country, adobe is considered an alternative building material. In Santa Fe, once upon a time, it was virtually standard: Nearly every home was made of adobe bricks. And, other than sweat equity, those building materials were basically free — families and neighbors got together to build walls using the earth as their supplier.
Today, adobe is an expensive construction method, in part because the house must be coated with a thick layer of insulating foam before stuccoing.
It is an excellent thermal-mass material, helping to keep a house cooler on summer days and warmer on winter nights. But it is not a good insulator.
Which leads to a discussion on alternatives. One of them is pumice-crete, a material that boasts thermal mass and good insulative properties.
Mark Giorgetti of Palo Santo Designs is working on his sixth home using the light, porous volcanic rock and is about to start another.
“The pumice is basically covered in a slurry of Portland cement and is poured into forms,” he said at a building site.
The thick, self-insulating walls are monolithic. Giorgetti adds 2 inches of rigid foam insulation on the exterior before stuccoing for an even higher R-value, which measures thermal resistance. A standard house has an insulation value of about R-20, and his will be about R-30.
“This is a natural material and it’s locally available,” said Giorgetti, a 20-year Santa Fe