Living outside the box: Alternative building materials give homeowners more options
October 8, 2018
His love of plants may have something to do with Steve Miller building a straw-bale house. A professor of botany at the University of Wyoming, Miller began construction of his straw bale home two decades ago, after much research and designing.
He considered other alternative materials, such as using cordwood, which he considered aesthetically beautiful, rammed earth, or a house made of tires, but with land near Laramie, Wyoming, that is flat and receives endless Wyoming wind, he settled upon straw as his material of choice.
"I researched for years and years; I've always been interested in alternative construction and sustainability," he said. "It's something I could do myself. I never got a loan. I would save up and build a little bit, save up, build a little bit, and straw is definitely sustainable."
The day after 9/11, in 2001, Miller's two years of planning came to fruition, and he broke ground by pouring the box beams required of his style of straw home, a modified post and beam, in which the roofing system rests on trusses, as opposed to a Nebraska-style straw home where the roof system rests directly on the bale walls.
Due to Wyoming's lack of straw bale housing codes, Miller used New Mexico's codes.
"All the bales were tied to a 2×4 with galvanized fence mesh and set in on rebar," he said. "The corners are different. There are a lot of ways to do it, but I used the box beam system for that. I built the box, stuffed it with insulation, and tied it directly into the bale system."
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Miller chose gunite, also known as shotcrete, over the more-commonly used stucco on the exterior and interior walls. Sand and cement are mixed with the ideal amount of water while shot out with the velocity of a .22 caliber bullet.
"I used two-string bales with three inches of gunite," he said. "The walls of the house are two feet thick and have a value of R-51."
The R represents the wall, attic, or floor's ability to resist the flow of heat. With higher R figures, the better it insulates per inch of thickness, and typical wall insulation ranges from R-11 to 28.
Miller's 4,000 square foot home has never required more than $150 per month for heat in the dead of cold, windy Wyoming winters, or hot, windy Wyoming summers.
"It's very quiet, very energy efficient," he said, "and when it's 95 degrees, it's 67 inside."
Miller perfectly placed his home so that the sun goes directly over the house in summer.
Similarly, Mark and Myrna Betson set their earth berm home in Whitney, Nebraska, in the same manner. The sun doesn't permeate the home during the summer due to an overhang over their wall of windows and perfectly-placed positioning. In the winter, sun streams in through windows and heats the concrete floor.
"It's a heat sink in the winter and a cool sink in the summer," Myrna said. "Even without heat, these houses traditionally don't get below 56 degrees."
Earth Shelter Technology, a company from Minnesota, traveled to western Nebraska to set Betsons' home into a partial hill on their ranch where their family has been since 1888. They used forms to pour concrete for the roof and walls, which are straight up for about 7'8", much like a traditional homes, but the unique design of the ceilings offers a benefit necessary of an in-ground home.
"The curvature of the ceiling helps reflect light," Myrna said. "You don't really think you're in an earth shelter house; you don't feel like you're in a cellar."
Once the structure was in place, about 20 years ago, Mark and Myrna did most of the finishing work themselves.
"They put the structure in between Thanksgiving and Christmas," she said. "After they got the forms stripped off, we put up plastic in the holes for the windows so the wind and snow wouldn't come in. It was a heck of a big craft project."
Both styles of homes are fire resistant, an important factor given where both homes are located in fire-prone areas during drought conditions.
"In 2012, it felt like we were living in hell. There was fire and smoke and everything all around us," Myrna said when the area around Crawford, Nebraska, was dealing with forest and grass fires. "It burned the roof off, and we had trees too close to the west side, but no smoke or fire came in."
Several vent pipes on top of the home melted as well, but Myrna said had they had a conventional house, it would have burnt.
"When they had those big fires down in Colorado, amongst the diversity of homes, log houses and stick-built, those fires just burned right over the straw bale houses," Miler said.
The tight construction and thickness of gunnite or stucco creates a seal, leaving no fuel to burn. If built correctly, straw and earth berm houses can last for generations.
"I helped a guy in Douglas cut out a door that was too small because he had to be in a wheelchair. He built the the house in the '50s," Miller said. "We cut the door jamb, and it was as sweet as the day it was put in there."
There are a few downfalls, though minor, to building an alternative construction house. Miller considers the lack of zoning and difficulty obtaining insurance or loans a small setback.
"When you break away from how everybody has always built homes, it can be a little frightening," Myrna said. "Well, this house is going to take care of us when we get old and can't take care of a house. We just have to mow the roof once in a while."