|
Building tomorrow's home |
Energy efficiency is the driving force behind six
new construction techniques
BY PETER 0. WHITELEY |
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:
10-foot-long modules of polystyrene and cement; straw bales; broad panels that sandwich
thick layers of insulation between sheets of a plywoodlike engineered wood product; solid
walls made from a sprayed mixture of earth and cement; lightweight, hollow foam blocks;
and steel studs.
These new materials perform best along the
exterior walls of houses, but that's also where they must battle for acceptance. To prove
themselves, they must be economically competitive with traditional
"stick-building" techniques. At present they are slightly more expensive on
initial construction costs, although the rising cost of lumber and increased familiarity
with the new building processes have narrowed the gap. Lower long-term energy costs, speed
of construction, aesthetics, and the satisfaction of using "green" products are
where these materials really shine.
We followed the construction of six Western
houses that each used one or more of these new building systems. They show that
environmentally friendly architecture can appear in many guises, from thick, plastered
walls to vinyl siding.
|
|
 |
ABOVE:
South-facing window wall brings sunlight into curving, multilevel main room. The Rastra
blocks also form the interior walls, which have been plastered. Rounded edges add a softer
look.
LEFT:
Thick but lightweight blocks can be cut with handsaws, shaped with rasps, and glued in
place. Concrete and reinforcing rods fill the interior voids. |
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, more than twice that of traditionally framed walls.This system forms the curving walls of Phyllis Hunt's home in Napa,
California (above). The interior feels like a giant kiva; 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
the Rastra. In summer, the overhanging roof and trellises shade the interior.
ARCHITECT: Craig Henritzy, Berkeley
BUILDER: Cloutman Construction, Kenwood, CA |
| |
| Excerpt from the "Sunset
Magazine" - May 1998 by Peter O. Whiteley |
|
