Standard stick-built structures are not an ideal way to build. Why? Because they “burn, rot, acquire mold, are eaten by insects, and have poor insulation bridging and limited thermal mass characteristics,” says Greg Madeen, founder of Madeen Architecture and Construction in Durango, Colorado. Madeen points out that traditional, lightweight, wood-frame homes also are increasingly more costly; construction lumber is becoming more expensive, in part due to the adverse effects of fire, beetles, and drought.
Alternative building materials such as straw, dirt, and pumice—materials Madeen has used since the early 1980s—can cut embodied energy use and provide additional benefits to occupants. “These are natural materials that tend to be much healthier than modern synthetic materials,” says Madeen, who believes that true sustainability is interconnected with local materials and local labor, a combination that strengthens a community as well as the global environment. Reflecting on the 100 projects he has completed over the past three decades, Madeen says, “The third millennium will have a vast increase in beautiful, holistic buildings made out of various alternative materials that fit their sites and add long-term, real value.”
Rammed-earth walls also have been built for thousands of years. Today, moist aggregates are tamped by mechanical pneumatic rammers. Reject soils are used, and Madeen adds Portland cement for stabilization. The appearance of the un-plastered earthen walls, sometimes with added pigment, creates a distinctively contemporary aesthetic. “As with all earthen walls, rammed earth can help with energy efficiency,” Madeen says. The low-maintenance material is fire-resistant and soundproof and can tolerate both dry and wet climates. “The strong, thick walls also lend a physical and psychological sense of protection,” he says. Rammed earth performs best in warmer climates, though Madeen has developed a system for mid-wall insulation that he successfully implemented on a residence in Colorado.
Considered by many in the 19th century to be agricultural waste, straw bales were one of few materials available to settlers on the treeless plains. Today, they are regaining popularity due to their ability to achieve R-30 thermal insulation. When designed with south-facing windows that allow sun to strike heat-absorbing heavy elements (stone or concrete floors, for example), they become highly efficient and are, surprisingly, fire-resistant. Madeen’s straw-bale walls typically are 18 inches wide, which, though they eat up some of the building footprint, add stability to the building as well as other benefits. “The thick, undulating walls add a sheltering, artistic aesthetic that is hard to achieve with any other material,” Madeen says.
Adobe has been used in some form for thousands of years. Made from sand, silt, and clay, the sun-dried or hydraulically pressed bricks are valued in desert southwest climates where their thermal mass can moderate fluctuations between hot days and cool nights, though Madeen recommends using extra seismic mitigation (stabilizers) where applicable. Adobe construction is “heavy work,” Madeen says, but the appearance of true adobe is prized for its thick walls, soft corners, and gentle connection to the landscape. The builder typically uses bricks that are 10 inches wide and oftentimes made from site soils. In cooler climates, Madeen applies insulation to the exterior or mid-wall and typically uses plaster or cement stucco as a facing.
Pumicecrete is a form of lightweight concrete that has been in use since the Romans built with a similar material more than 2,000 years ago. Not yet common in the United States, Pumicecrete is slowly gaining popularity. “I think we are going to see a lot more lightweight concrete construction when people become more aware of our current, short-sighted building techniques,” says Madeen, who has used pumicecrete in roughly fifteen projects and describes the material as “homogenous,” meaning the pumicecrete wall serves as the structure, the insulation, and the thermal mass. Pumicecrete readily accepts plaster as an interior and exterior facing without the need for metal lath. “This … leads to substantial monetary and embodied energy savings,” Madeen says, who suggests using pumicecrete for contemporary architecture.