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RE: GSBN:Re: Moisture in SBW
- To: "GSBN" GSBN@...
- Subject: RE: GSBN:Re: Moisture in SBW
- From: "strawbalefutures" info@...
- Date: Wed, 20 Oct 2004 11:30:06 +0100
- Reply-to: "GSBN" GSBN@...
- Sender: "GSBN" GSBN@...
Sorry to hear of these problems but as John Straube has also said, it can
happen in any house whatever it's made from. We've had to repair damp in
some buildings over here. The main thing is that you've had a good look at
where it is and what's causing it.
So I agree the main issue is to put an overhang on the roof, and possibly a
pitch as well, flat roofs are notorious for letting in the weather.
The elastomeric stucco - that must be a coating on the top? I would hesitate
to sand blast it as you may lose some of the straw as well. We've taken
plaster off straw using heavy hammers and claws, you can scrape it out of
the straw - but we plaster directly onto straw, was a metal coat used here?
But I would take out all the sills and put a damp proof course under them,
paying attention to laying it up the sides, in agreement with John here. If
the sill is laid onto straw and not onto cement then you can scrape out a
slot in which to insert the damp proof course without removing the sill.
With the stucco a breathable flexible plaster would be better, either lime
or clay with limewash. Cracking in rigid plasters like cement, which then
let in moisture, is a common problem. But you will always have the problem
of stucco onto the cement horizontals. I'm not surprised the cement is as
wet or wetter than the straw. It is what we call a 'wet' material and we
wouldn't be able to get away with it here in the UK. If there is any
moisture in the walls it will tend to be drawn to the cement.
Your best bet is to take the stucco off in the area of damp, take out any
obviously wet bales and replace them (it's not as bad as it sounds, we've
successfully replaced bales in a loadbearing house). If you want to dry the
walls out without replacing straw then we did it on one house by making
holes the whole width of the wall in the areas of greatest moisture, and
letting a drying wind blow through it. This can only be done in the drying
season! Winter is not a good time to take the stucco off- maybe leave this
part of the repair till spring/summer? Make sure you deal with all the damp,
Hope you get it sorted out.
From: GSBN [<a target="_blank" href="mailto:GSBN@...]On">mailto:GSBN@...]On</a> Behalf Of Danny &
Sent: 20 October 2004 00:56
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 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 wall.
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. Why?
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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