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If using local materials
follows the "close-to-the-source" principle, then the closet source is the
site itself. The great majority of the materials for traditional
construction-soil, wood, rock-was taken from the site or very nearby.
Limitations on locally available materials played a strong role in the
development of regional technologies and design styles. For example, the
high deserts of the southwestern United States and Mexico have tall trees
only in limited mountain areas. This led directly to the use of
adobe---earth from within the building's footprint, in many case---as the
main building material in these regions, with timber reserved for roof
beams and door and window lintels.
Far from being just a
constraint, these local materials awakened a creative design response that
has become one of the most popular and imitated styles today. A wide
range of on-site materials may be productively reused in the landscape-if
the designer takes the time to look and consider them creatively. In an
era when the homogenizing effects of industrial, Modernist design are
widely regretted, creative use of local materials offers not only
environmental benefits, but the basis for artistic rebirth.
Elsewhere in this book, we
argue for removing old paving and structures and restoring the soil
underneath, but where the structure can be adapted, or where energy costs
of removal are high, it may make more ecological sense to leave such
structures in place and simply work around them. An example is Monnens
Addis Design in Berkeley CA, where a defunct warehouse was rehabilitated
as a graphic-design studio. The owners of the business wanted a garden,
but the only available spot was the former warehouse's loading dock,
covered with a concrete slab 8" thick. The landscape architect for the
project, Jeffrey Miller, chose an unusual strategy: instead of demolishing
the slab, he built the garden atop it.
Cost was an obvious factor
in this decision; transporting and demolishing debris have become a
significant expense in most cities, as local landfills reach capacity and
dumpsites migrate farther and farther away. But beyond this pragmatic
consideration, Miller is a believer in the use of on-site materials.
"I've found that if you can leave things where they are," he says, "you're
not spreading more junk around the planet."
Miller did have to punch
through the slab to create planting pits for four weeping acacia trees,
one queen palm, and two species of bamboo. To cut the pits, Miller
brought in a subcontractor with a diamond blade saw. Miller even used the
rubble from the holes by piling it against the building to create raised,
planted seating areas. First compacting the rubble by mechanically
vibrating it, he then filled any voids in the mounds with gravel and sand,
and finally added 18 inches of soil. The striking results can be seen in
Figure 6.8. | |
