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RE: GSBN:Re: Moisture in SBW
Sorry to hear about the house problems . If the owner of the SB feels
down, I can send pictures of similar situations with lots of rotting
wood for framed houses.
The detailed description is quite useful.
Before trying to help, I would like to point out a couple of general SB
observations that your description prompted
a. It would seem that an overhang would be a really good idea for SB. I
would be interested in knowing if this is a directional thing (eg which
orientation is wettest). It supports almost everything I have seen in
other SB failures and in fact in many other buildings. Overhangs ARE A
REALLY BIG DEAL. Pitched roofs also help BTW.
b. All but one of the problem SBs I know had problems around the
windows. Windows leak. They all leak. In regular construction they
are turning into the number one problem locations. SB is not different.
Trying to be helpful to you I would offer
1. A repair should likley include the addition of an overhang or roof
projection of some sort, since the lack of one is a cause of the problem
2. I am not sure what elastomeric stucco is (do you man an elastomeric
coating on stucco?). In either case, I would recommend a cement-lime
stucco and, if you cant get a decent overhang and experience shows the
plaster absorbs rainfall often, a siloxane water repellent treatment.
3. The stone sill may be leaking at the sides so I cant think of any way
other than removing the sill and the window and placing a waterproof
layer underneath -- say building paper or such. Beware the sides and
any joints. Also, the sill should project out from the wall about 2",
have a drip groove, and have jamb extensions (sill wider than jamb) of a
couple inches too.
4. I would not try to dry any straw that smells musty --- you should
replace this. Drying damp straw can be done, but best when it is sunny
and dry outdoors. The only way to accelerate is to heat the straw
combined with a little bit of fans to blow the evaporated moisture away.
This can be done by heating the interior (with the stucco still on) as
much as possible with lights and such (have done this successfully in
5. Replacement of straw caly is not that cray. If you use a low density
version of clay slip over straw, do it in layer of 4 to 6" with good
drying in between (aided by lighs etc) it should work. Cant help more
without trying it a bit.
Sorry this is all I can offer
It would be great if you could keep the list informed of what you learn
-- wecan all learn something from failures, and I prefer to do it from
School of Architecture and Dept of Civil Engineering
University of Waterloo
<a target="_blank" href="http://www.civil.uwaterloo.ca/beg">http://www.civil.uwaterloo.ca/beg</a>
From: GSBN [<a target="_blank" href="mailto:GSBN@...">mailto:GSBN@...] On Behalf Of Danny &
Sent: October 19, 2004 19:56
Subject: GSBN:Re: Moisture in SBW
Haven't spoken up for a while, but am following what's going on. Thanks
for all the good SB energy.
I have been called in to look at a house that I did not build, but was
showing a spot of moisture in one of the interior walls in the mud
plaster.After some investigation, we have found extensive moisture
throughout one wing of the house.This wing has a flat roof with no
overhang. The other two wings have overhangs and are testing dry.
Moisture in the former is as high as 40% in spots, but a lot of areas in
the low 20% range. The pattern seems to be mainly under the flagstone
window sills (about 8" deep and probably without any flashing under the
flagstone.). The other main factor seems to be that the entire house has
elastomeric stucco. The owner has been caulking cracks in the stucco,
which appear to be caused by moisture buildup- ie the areas along cracks
tend to be very wet just below the stucco.
The house was built with a system local to our area caled "bale block".
This a system where two 4" diameter holes are drilled through each bale
prior to it being laid into the wall. After two courses have been laid,
a 4" PVC is used as a form and a reinforced concrete column is poured
through each drilled hole, the PVC then being extracted. At every other
course, a 2" reinforced "beam" is poured the width of the bale. Thus we
have a concrete grid running vertically and horizontally throughout the
The owners are committed to making the house right (and rightly so for
everyone's sake). Here are some questions under consideration:
1. We want to strip the house entirely of the elastomeric stucco,
replacing it with a cementitious color coat where the walls are dry. We
are thinking of sand blasting it off. any other ideas?
2. The stone sills run the full depth of the straw bales, with the
windows set on top of them. Is there any realistic way to make this
waterproof without tearing out the entire sill?
3. We are expecting to tear out straw, wherever it is wet. Ibelieve it
will be difficult but doable in spite of all of the concrete. I am
thinking that we can get some drying once the walls are opened up, but
doubt that we can expect to really dry more than a few inches from the
surface. Can we dry deeper than that? What parameters shoud we use in
deciding how much straw to extract? When the moisture meter hits
concrete in wet areas, the concrete is as wet or wetter than the bales.
4. Once straw is pulled out, with the concrete grid still in place, what
can we possibly refill the walls with?. The moisture tends towards the
outside of the walls, so we are hoping to keep the interior surfaces
intact and just work from the outside.When refilling the walls, we want
to keep moisture to a minimum, so straw clay or other poured or puddled
materials seem unlikely. I do not see how to use straw realistically-
would that be possible? We are going into winter here.
5. I have not had a chance to investigate any possible coverage from
liability insurance the original contractor may have carried. Would we
expect this to apply? The house is about 4-5 years old.
I am sure that other questions will arise as we proceed. This a very
beautiful home, with lovely interior finishes. One problem inside is
that the clay floors are wearing poorly around furniture. They want it
replaced with colored concrete. Any ideas on this?
Look forward to a response. Anyone want to do some volunteer (or perhaps
paid) work on forensic straw bale?
Santa Fe, NM
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