Alternatives
builder. The pieces of pumice are about the size of peas, so the texture of the raw wall (before plastering) resembles that of a Rice Krispies Treat.
And the material is sculptable. “On this house, we’re aiming for square corners because it will be a more contemporary design, but it’s easy to do rounded, bullnose corners.”
For the same reason, the builder can sculpt arches in doorways or carve out nichos in the walls.
“It has the same structural quality as adobe and at a fraction of the cost,” Giorgetti said.
Down in Placitas, Cadmon Whitty is building two houses with another alternative material — straw bales. The owner of Paja Construction Inc. lauds straw’s extraordinary insulation quality.
“If I do R-45 straw-bale walls in concert with superinsulating ceilings up to R-70 and use energy-efficient doors and windows,” he said, “you can practically heat these houses with a candle.”
Whitty has built straw-bale homes since 1991, including in Santa Fe and Española.
He said that trees have to grow for decades to produce two-by-fours, and most of the market lumber in this area must be transported from the Pacific Northwest. Instead, he buys straw bales from southern Colorado.
“The one big disadvantage of the straw-bale house that may affect the cost, because the walls are so thick — at least three times as thick as a conventional two-by-six wall — is that you’re losing more interior square footage,” he said. “Because of that, people may want to increase the house footprint.”
What about moisture, pests and fire danger?
Whitty says proper use of Sheetrock and stucco will seal a straw-bale home, just as they do on a conventional house. But the stucco should be quite thick, in order to even out the straw surface and to provide additional strength.
“Rodents won’t be chewing through an inch of concrete stucco,” he said.
The bottom line: “You can create beautiful houses that look like adobe for a fraction of the price,” Whitty said.
More than 12 years ago, Scott Cherry began working with another builder, Robert LaPorte, and architect Paula Baker, using a material called “light straw clay.” It’s a high-performance natural wall system that Cherry’s company, Lightfoot Inc., recently used for a dining room addition at the historic Donaciano Vigil House on Alto Street.
He and Baker worked on writing the light straw clay language for the International Residential Code. As a result, the Vigil House addition was the first permitted light straw clay project in Santa Fe.
It’s a natural, nontoxic material that is stuffed into a wood-frame wall structure. Light straw clay walls are pest resistant and breathable, and they boast a great ability to manage moisture.
In a September interview, Cherry said hot, moist inside air can enter the wall of a standard house through outlets and gaps in the drywall. Once inside, it can condense on the plywood sheathing, creating perfect conditions for mold to grow.
“But clay is hydrophilic,” he said. “Any moisture that gets in is absorbed and dispersed to the next available dry clay particle. There’s no barrier for it to collect on.”
The alternative construction realm today also includes structural insulated panels; rammed earth; insulated concrete forms; recycled international shipping containers; and earthships made out of old tires, bottles and mud.
ALTERNATIVES AT A GLANCE STRAW BALE
Advantages: Extremely high insulation value (R-45), compared to R-20 for a standard two-by-six frame wall. It’s also a natural, renewable resource that produces handsome, thick walls.
Cost: About the same as a standard wood-frame house, although you might want to build larger because the thickness of the bales — either 18 or 24 inches — means your interior space will be 3 or 4 feet smaller in both dimensions.
PUMICE-CRETE
Advantages: With rigid insulation on the exterior, it has a very high insulation value (R-30) and provides thermal mass to moderate interior temperatures. It’s also a natural, local material and mold free. Pumice-crete also produces thick (about 15 inches) walls.
Cost: About 20 percent more than a standard woodframe house.
LIGHT STRAW CLAY
Advantages: Good insulation value (R-22), plus it’s nontoxic and resistant to mold, insects and rodents. Plaster and stucco may be directly applied. Thick (about 14 inches) walls.
Cost: About 5 percent more than a standard woodframe house.