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GSBN:More about dip

Hello all,

I was briefly involved in retrofitting stick frame house from 1972 in
Massachusetts with straw bales. The owner of the house was afraid of
moisture. He assumed that he needs to take the existing red wood timber
cladding on the exterior of his house down before placing the bales to the
outside of existing wall, because he thought the cladding covered with straw
bales would rot away.

Straw bale wrap will push the whole existing wall assembly into the warm
side of the wall, so that there is no danger of condensation. I still have
WUFI moisture simulation software for a thesis research. I ran the existing
assembly (sheet rock, leaking plastic vapour barrier, fiber glass 4",
plywood, red wood cladding) with straw bale wrap lime platered on the
outside through simulation in Boston weather. Existing timber cladding
covered by bales was absolutely fine (sim. showed low humidity levels in
that area), but I didn't like the results of simulation in the straw bale
wrap. Relatively impermeable existing wall assembly pushed the humidity in
straw bales up when I compared the results with simulation in the same
climate on classical straw bale wall (limeplaster, straw bale, earth
plaster). So I tried Tom's trick with dipping the straw bale face (the one
adjuscent to existing wall) in clay. Simulation showed great difference in
humidity inside the straw bales. 2" clay dip kept the humidity across bales
in the same level as it would be in our traditionally  plastered straw bale
wall, despite the relatively impermeable existing structure on the inside of
the building. There is another reason I like the idea of dip in this case. I
believe that it preserves the existing timber cladding buried under the
straw - as we know that ancient timber is always well preserved when in
contact with clay in old wooden-cob structures.

I don't have any practical experience yet, just another theory, but I'm
hoping to do the workshop on this building next year and I'll dip the straw
bales and let them dry a bit before placing them tight next to the existing
timber wall.



----- Original Message -----
From: "Martin Hammer" mfhammer@...
To: "GSBN" GSBN@...
Sent: Saturday, May 26, 2007 8:51 PM
Subject: GSBN:Upon reflection

GSBN members,

I send this without reading any response to my last impassioned e-mail.
was misplaced and I just let it go in the moment.  The GSBN is about straw
bale and natural building.

At the same time we are all working in local, regional, and worldwide
contexts, and occasionally there's an elephant in the room that is too
to ignore, even if there is no direct or apparent connection between it
straw bale.

But of course this could easily get out of hand, so one must use great
deliberation to go off topic.

So I'll bring it back to bales by saying the following:

Andre's comment (about Sarkozy/Bush) lit a match under me.  I was a bale,
clearly on-edge, whose strings had broken, and I went up in flames.

I'll try to keep a fire-extinguisher nearby in the future.

Martin Hammer