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Re: GSBN:Loadbearing sb with moisture damage



John,

The old practice that is in a lot of the older approaches in books and
elsewhere, of just putting some sort of waterproofing material over the
top of the bale, under the rough buck and lapping it down a ways on the
outside doesn't get the water out of the wall, just moves it down the
wall under the window but it's still inside the plaster. The key for
the pan idea is that it has to come out beyond the exterior surface of
the plaster. You can do this pan below the material you use for your
finished sill, if for example you use wood or tile or stone. The
finished sill material would cover this pan flashing, though if you
used copper for instance, (I know that some people are concerned with
various issues of using copper) you could just let it show and have it
extend beyond the plaster and have a drip edge.

What is critical is exactly your point though, to get the water
collected OUT of the wall completely. And there are conventional
details that work or can be accomodated for the differences in bale
walls.

David

-----Original Message-----
From: John Swearingen jswearingen@...
To: 'GSBN' GSBN@...
Sent: Wed, 8 Mar 2006 09:06:26 -0800
Subject: RE: GSBN:Loadbearing sb with moisture damage

  I've just been reviewing some details from CASBA members--we're
putting
together a CD of details that will be available, perhaps in six months.
In
a way, waterproofing is just the same as any good practice in
conventional
construction, but...the big question is, if you have a pan under a
window,
do you (or how do you) shunt any water collected there to OUTSIDE the
plaster wall.  Even here, there are conventional details from brick and
even
stick construction.

John

John Swearingen
SKILLFUL MEANS
design and construction
www.skillful-means.com


-----Original Message-----
From: GSBN [<a  target="_blank" href="mailto:GSBN@...";>mailto:GSBN@...] On Behalf Of Chug.
Sent: Wednesday, March 08, 2006 8:45 AM
To: GSBN
Subject: Re: GSBN:Loadbearing sb with moisture damage


Hi David

Thanks for this, I was just going to ask what are peoples latest 'best
practice' methods for the waterproofing detail of SB window and door
openings, as this is one area where I feel there is not much info out
there
and even less in pictures, anyone else got anything on the subject?

bale on
Chug
chug@...<a  target="_blank" href="http://www.strawbale-building.co.uk/";>http://www.strawbale-building.co.uk/</a>
.
----- Original Message -----
From: strawnet@...
To: GSBN@...
Sent: Wednesday, March 08, 2006 3:52 PM
Subject: Re: GSBN:Loadbearing sb with moisture damage


Laura, Chris and all,

The issue of good moisture detailing for windows is, in my view, one of
the
most important and most often neglected aspects of sb design and
construction. When you talk with the people who look at moisture
failures in
buildings for a living, this is often cited as the most common or one
of the
most common areas of moisture damage and failure.

  It is a more important issue to get right in bale walls because they
are
susceptible to moisture damage. That it is so often a problem in
conventional construction should not make us less vigilant or diligent.
And
this is important - good design and detailing should never rely on
caulking
as the only method of preventing moisture from getting into the walls
around
windows.

Here is my ideal scenario - what I would like people thinking about as
they
design their detailing for openings in bale structures. There should be
flashing all around the opening that is, in essence "shingled" -
overlapped
starting from the bottom, so that any leaks are directed onto (not
behind)
the next piece of flashing, and eventually, out of the wall. There are a
number of products available with which to do this and this is one place
where I think the judicious use of synthetic materials makes a great
deal of
sense. This flashing should not just be applied over the surface of the
plaster, but should start, ideally, behind it so that the plaster is
actually part of the shingling system.

I'm a big proponent of having a sill pan (which can be made of hard or
soft
waterproof material - could be the same material as the rest of the
flashing), which extends underneath the window and a bit beyond each
side of
it, is turned up at the back and sides (so that water can't run off the
back
or ends into the wall), preferably slopes to the outside, extends
beyond the
exterior finish surface, and has a drip edge.

The less weather exposed the window, the less critical this detailing
is.
But if the wall above the window is going to see rain, ideally we would
have
a piece of flashing that extends above the top of the buck and up
behind the
plaster. I know this is a challenge, especially if you are cutting an
opening into the wall after plastering. But if the top of the buck had
even
a small strip of wood nailed to the top and set back so that it was
behind
the inside surface of the exterior plaster, the flashing could be
attached
to the top of this strip and extend out and down the face of the top of
the
buck. It should be long enough to be able to  overlap over the top of
the
window as well as the top of the side flashing. Then, moisture that got
to
the inside face of the stucco above the window, and moisture that leaked
behind the trim at the top of the window would not be able to end up
inside
the wall or sitting on top of the window buck or the top of the window.

It is important to note that caulking, even the best caulking, is only
going
to reliably last a few years. If it is all that you are depending on to
keep
moisture out, and it is hidden by trim or in places you rarely or ever
inspect and maintain, you have designed in a problem rather than
designing
it out. It's much easier to think these things through before you build
and
if it's too hard to visualize this, build a mock-up, a model, of what
you're
thinking about building and work out the details at full scale where
you can
try different things and even test them...

When I was building, I used to try to think like water - how could I
get in
and how could I get out. Use great care in your efforts to keep water
out,
and, knowing that you will not be able to achieve this completely, take
as
great an amount of care making sure that the water that does get in can
get
out. Of course I also used to think that you "only had to be smarter
than
water" to do this and it turns out that like many others, I had woefully
underestimated the IQ of water...and similarly overestimated my own...

What  I love about this forum is that we are, as a group, so interested
in
learning from our own and others mistakes and discoveries and sharing
that
learning openly.

David Eisenberg

-----Original Message-----
From: Laura Bartels laura@...
To: GSBN GSBN@...
Sent: Tue, 07 Mar 2006 20:50:30 -0700
Subject: Re: GSBN:Loadbearing sb with moisture damage

  Regarding cutting out windows after basecoat (or all coats) of
plaster,
  I have always scratched my head over doing good moisture detailing
after
the window does go in. Any comments?  Laura

Chris Magwood wrote:

 > From our point of view, it took about the same amount of time to  >
frame
everything up first and then stack and plaster compared to  > stacking
and
plastering and cutting out later. The reason we didn't  > keep doing it
this
way? Well, what do you do with a bunch of 3x5  > foot, 21-inch thick
hunks
of bale wall that weigh hundreds of pounds  > each?  >  > Chris  >  >  >
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GSBN is an invitation-only forum of key individuals and representatives
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are underwritten by The Last Straw Journal in exchange for use of the
GSBN
as an advisory board and technical editing arm.

For instructions on joining, leaving, or otherwise using the GSBN list,
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GSBN is an invitation-only forum of key individuals and representatives
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regional straw construction organizations. The costs of operating this
list
are underwritten by The Last Straw Journal in exchange for use of the
GSBN
as an advisory board and technical editing arm.

For instructions on joining, leaving, or otherwise using the GSBN list,
send
email to GSBN@...HELP in the SUBJECT line.
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GSBN is an invitation-only forum of key individuals and representatives
of
regional straw construction organizations. The costs of operating this
list are
underwritten by The Last Straw Journal in exchange for use of the GSBN
as an
advisory board and technical editing arm.

For instructions on joining, leaving, or otherwise using the GSBN list,
send
email to GSBN@...HELP in the SUBJECT line.
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