>What are caulks used for in joints that move? Aren't Marc's movement
>concerns about thermal expansion?
Some joints can be expected to move significantly more than others, and
not all movement is due to thermal. Some materials move due to moisture,
and in larger buildings seismic, vibration and other mechanisms come into
play. For example, the joint between a wood window casing and wood
clapboard will move very little; the joint between a large aluminum
window frame and a masonry wall would be expected to move a lot; and the
joint between two sections of masonry veneer curtain wall attached to
structurally isolated steel frames would be expected to have very
significant movement. A joint must be designed, and a sealant selected,
to accomodate the anticipated movement.
>What is the basis for the notion that one is "more sustainable" than the
>other? I would like to know your criteria and the data you use to evaluate
>the alternatives against those criteria.
I'm not proposing that a sealed joint is "per se" more sustainable
than one that is not. The point is that one must evaluate for EACH
PROJECT what the criteria are. In this case perhaps that is a
person's chemical sensitivity versus energy savings. As far as
issues like the embodied energy of sealants versus the energy they
save, I don't think lengthy calculations are needed to see that
fixing a leaky house will be more sustainable since a little
sealant can stop very large leaks.
What is your point anyway Hal? That my outlining the basic issues
is "unscientific" or invalid because I didn't cite some data? If
you have data that shows I'm incorrect, then state it. The recent
postings about measuring sustainabilty clearly show that this is
complex to determine, but that doesn't mean we should make no
decisions at all if the information is less than complete, or
especially, in relatively simple decisions like this one.
John Bunzick
Dean Architectural Alliance, Inc.
HKT Architects, Inc.
bunzick@tiac.net
__________________________________________________________________
This greenbuilding dialogue is sponsored by Oikos (www.oikos.com)
and Environmental Building News (www.ebuild.com). For instructions
send e-mail to greenbuilding-request@crest.org.
__________________________________________________________________