Rastra Home
Standard dimension, softwood lumber used in conventionally framed houses is
being challenged by a new generation of alternative building materials....rastra is
one of them. Rastra homes are built from a pre-cast forming system that uses
long modules made of recycled polystyrene and cement that contains cavities for
rebar and concrete. The polystrene and air gaps in the block add insulative
properties that give the walls more than twice that of traditionally
framed walls. So not only is the material environmentally friendly, but it's also
energy efficient. - two key elements in the home of the future.

Interviews:
Greg Otto, Integrid Building System, Inc
Phyllis Hunt, Rastra homeowner
Craig Henritzy, Architect, Indigenous Design

Featured Products and Services:
Rastra - a pre-cast forming system using long blocks made from recycled polystrene and portland cement
Integrid Building System, LLC
PO Box 5298 Berkeley, CA 94705
(510) 845-1100

Indigenous Design, Architect Firm specializing in ecological and natural approaches to architecture
8 Indian Rock Path, Berkeley, CA 94707
(510) 526-8602 http://www.henritzy.com

... The center for Continuing Study of the California Economy in Palo Alto predicts that the state's population will grow to 37.8 million by 2005, with the greatest concentration being in the eastern San Joaquin Valley and eastern Sacramento regions that interface with wildlands. The fastest growth will therefore be in areas extremely vulnerable to fire, and with a history of using building materials and methods that put new communities at a great risk of destruction.

Fire safety preparation must extend ... to those responsible for planning, designing, developing and maintaining the homes and workplaces in which people function. These include architects and engineers, developers and builders, financial institutions and insurance companies, all parties to the same enterprise though often with vastly different , competing, economic agendas. cost compromises involved in developing new communities traditionally have placed fire safety in urban/wildland areas at a low level of priority. One simple way to elevate this priority and mitigate competing interests is to specify and support the use of cost-competitive building materials for structures that will resist fire even in conflagration proportions.

California has long invited residentially-destructive wildfires because of the predominant use of wood in construction. California Department of Forestry statistics indicate that the 20 largest structural losses from urban/wildland fires since1923 equal 13,642 buildings, of which 2,755 of these were destroyed predominantly in the Bay Area and Los Angeles Basin prior to 1988. I

In all the above cases more than 98% of the destroyed structures were primarily made of lumber. The Solution therefore seems simple: design and build with a fire-resistant material that is cost competitive with wood. I've done so, on many occasions, since 1992.

The material I've used is called Rastra. This stay-in-place concrete forming system has a four-hour fire rating at 2000F and other admirable features as well. The data gathered from Rastra fire endurance tests conducted by Braun Intertec Corporation have set new performance standards for those who are serious about building responsibly in urban/wildland interface developments.

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.