Building Tomorrow's Home

by Peter O. Whiteley

Energy efficiency is the driving force behind ...new construction techniques

Greener pastures are on the horizon for residential construction now that homeowners, architects, and builders can choose environmentally friendly ways to build or remodel. Standard-dimension softwood lumber (2-by-4s and 2-by-6s) used in conventionally framed houses is being challenged by a new generation of alternative building materials....(like) modules of polystyrene and cement.

Rastra -- It's called Rastra: a precast forming system using long modules made of recycled polystyrene and cement that contain cavities for rebar and concrete. Despite their massive appearance, the 10-inch-thick, 15-inch-tall, 10-foot-long blocks weigh only about 150 pounds and can be glued together horizontally or vertically. The polystyrene and air gaps in the block add insulative properties and, when sealed, give a 10-inch-thick wall an R-value of 36 or more, more than twice that of conventionally framed walls.

This system forms the curving walls of Phyllis Hunt's home in Napa, California. The house blends Southwestern and Native American architecture with passive solar design. It notches into the slope and orients the two-story main room toward the south. In winter months, low -angled sunlight stores its energy in the mass of the colorful concrete floor and the thick plaster coating of the Rastra. In summer, the overhanging roof and trellises shade the interior.