Cohousing-L Mailing List: Sustainable materials and design

[Tom Lent (tlent]

BERKELEY COHOUSING: SUMMARY OF SUSTAINABLE MATERIALS USE & DESIGN
September 25, 1996 by Tom Lent

It has been a priority to find ways to maximize our use of environmentally
sound materials and design in this project. We have had several successes
and several disspointments as we have succeeeded in including some elements
and not others. Our failures are in part due to the nature of the state of
the art, in part to budget limitations (we are working under affordable
housing price guidelines as well as our own pocketbook restrictions) and in
part to our own lack of time and energy to pull off this whole crazy project
and do all the research we would like to do to push the envelope on
sustainable material use.

Our sustainability concerns started before construction with the site prep
and demolition. We salvaged and milled the acacia trees that we had to cut
down (they were nearing the end of their life and starting to come down of
their own accord). We plan to use the lumber for interior stairs. We had a
large palm tree that needed to be removed, transplanted to a new home. We
salvaged lots of bricks and lumber from the demolition process and the
contractor source seperated most of the wood and concrete and asphalt
roofing material for recycling.

Starting from the ground up, we are using concrete with a 15% mixture of fly
ash, a recycled waste product from coal fired power plants (I'd rather not
have any coal fired power plants, but if they must burn the coal, at least
we can make good use...) replacing some of the energy intensive cement. It
also makes for a stronger and more workable product.  

Our mud sills (the wood that goes on the concrete foundation) will be
treated with "ACQ Preserve", an alternative to the usual copper-arsenic (ACA
or CCA) preservatives. 

We investigated the possibility of using straw bale construction but
returned to traditional stick framing because of severe space constraints in
our urban infill situation. This meant that we could ill afford to give up
the 100 square feet or so that the thick bale walls would occupy in each
unit. It also meant that we needed to build two story buildings. Since
Berkeley had yet to approve a one story bale house, starting with a two
story house was too large a leap. We will be using straw bale construction
for our sound wall at the end of our property that fronts a noisy busy street.
 
We had high hopes of being able to use sustainably harvested wood for the
framing and sheathing, but alas could not. It is not yet available
commercially at all in plywood and found that Douglas Fir framing is not
available predried off the shelf (it can only be purchased milled to order
and delivered green). Since we didn't have time to store it ourselves to
dry, we could have serious moisture problems. This could mean problems with
warping wood and popping nails down the road. Hem fir was available kiln
dried, but also had long lead time for delivery. Lesson learned: Get your
lumber list together before construction loan close so you can place your
order at the earliest possible time. Oh well, as Katie says, at least we are
part of creating the demand for those who will follow us. Some day soon it
will be available dried off the shelf if enough of us are requesting it.

We will use certified sustainably harvested redwood for the decking. We are
using carpet made from recycled materials and flooring made from bamboo
instead of wood in all units except one in which we are using hardwood
flooring salvaged from another older unit. On the roof we will use
fiberglass composite shingles, much less toxic than standard asphalt
shingles. We are using low VOC paints inside and are investigating the use
of recycled paints on the outside. 

We wanted to avoid using PVC in the plumbing due to the toxic nature of its
production and disposal and concerns about its impact on water quality. We
ended up splitting - spending the extra money for copper for the water
service work, but resorting to PVC (instead of clay) for our sewer work for
price and resilience reasons. 

Our energy designs, both in heating and in lighting far exceeds the state
standards. We will have plumbing installed and strong south facing roofs for
future solar water heating option on all new units.

The best news is that we are doing all of this at little or no extra
financial cost - in most cases just the cost of our time to research, find
and evaluate the options, important in this project with serious price
constraints.

Of course, the project inherently has positive environmental impacts beyond
these design and materials issues. As urban infill near downtown Berkeley
and on bus and subway lines to downtown San Francisco, we are providing more
housing that is walking and mass transit friendly. By our community
orientation (common meals, shared childcare, group social activities), we
cut our needs to drive and to own more redundant appliances (like washing
machines) dramatically.

For more info about how to join our comunity, contact us at 510/549-3749.
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Tom Lent * 2220 Sacramento St * Berkeley, CA 94702-1907
           email: tlent [at] igc.org * phone: 510/845-5243
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