[Strawbale] windowsill waterproofing etc.

[Raftercat5 at aol.com]

Date: Sat, 07 Apr 2007 14:53:38 -0400
From: Frank Tettemer  <frankt at webhart.net>
Subject: Re: [Strawbale] Jeff's recessed  windows
To: Strawbale at listserv.repp.org
Message-ID:  <4617E8B2.8060105 at webhart.net>
Content-Type: text/plain;  charset=ISO-8859-1; format=flowed

Hi all, and especially Kathy,
In  response to your query to Jeff, about materials,
I'm offering this to the  list, (as a discussion element.)

I have a few favourite materials for  building my under-window-sill 
drainage-pans:
(First, I've gotta say, that  in the aim of conservation, each unique 
building will have some sort of  waterproof materials, already on site,
having been specified for other  building components.  So, as an act of 
non-consumerism,
I use any  one of these *three* material choices.)

First favourite:  Usually,  in our area, where covered-seam steel roofing 
is a frequent and practical  choice, there is bound to be some soft steel 
or galvalume or aluminum rolls  stock ordered, to be used for the roof 
flashing, valleys, etc.  I buy  enough extra to do all the windows, 
(buy-a-full-roll,-and-save  attitude).  And likewise, I add on extra tar 
paper, felt paper, or  tyvek that is being used, elsewhere in the building. 

The pan gets built  with thin 1/2" strips of cedar shingles, used as fill 
between the bottom of  the window sill, and the top surface of the metal 
pan. This achieves the  goal of maintaining a sloping outward grade to 
the pan, assuring flow in the  right direction.  It also helps stuff the 
space with drain-able  material, and cuts down on wind infiltration.  On 
the inner face of the  window, inside the house, the pan is bent upward, 
vertical, about a half  inch, and siliconed and stapled to the inside 
face of the window frame. This  half inch of aluminum is later hidden by 
the installation of an interior  wooden trim piece, or, a wooden plant 
sill. Like wise, the metal is  corner-folded, and bent upwards and 
stapled on the left and right sides of  the window.  This forms a flat, 
sloping pan with three vertical  sides.
The final act of drainage, is to use some building-supply drip edge,  or 
shingle starter, or other factory-folded readily available aluminum trim  
pieces.  This goes under both the window pan, and the external sill,  (if 
used), and extends just a bit further outside of every component, to  
cause the drips to miss the plaster immediately beneath the sill  area.

The tarpaper or felt or tyvek mentioned in the above ingredients,  gets 
placed above the bale, but below the metal window pan.  It acts as  a
second-layer defense. This is an attempt to also drain away any  
condensation that might occur during extremely cold weather.  The idea  
here, is
that if there is moisture laden warm air migrating through the  bale wall 
assembly, then the air could, (and likely would), condense on the  under 
side of the metal pan.  So the tarpaper takes this wear-and-tear,  
instead of wetting the bales.

Second and Third  favourites:
2.)   under ground foundation material, (such as  Blueskin ... a rubber 
product).
3.)   or an  under-tile-floor-shower membrane, (such as the Schluder 
system).
I'd use  them in the same assembly system, as described above for the 
aluminum  pans.

These two materials have the advantage of offering much less heat  
transfer. 
So they don't act so much like a thermal bridge, as the  aluminum 
material does.

To help promote discussion, I invite others  to poke holes (figuratively) 
in the above methods.
There's enough  experience here on this list, to come up with some 
solutions or methods,  without holes.
I would imagine that there would be different  approaches,
reflecting the different types of climatic environments.
And  different types of humour.

Frank Tettemer
www.livingsol.com
 
Frank (and everyone):  What you said makes lots of sense.  If a  tar paper 
were used on top the straw and wood window buck, then the shower pan  rubber 
material on top of that, it seems to me that it would make it not only  
waterproof, but also, it seems like it would prevent condensation under the tar  paper. 
 Also some type of caulking around everything after the window is  installed 
should protect it further.  What do you all think?   Since we'll be using lime 
plaster, the walls will be able to breathe, so we  shouldn't have too much to 
worry about as far as moisture is concerned, as long  as we don't have any 
leaks around the windowsills and other vulnerable  places.   This is all still 
'miles down the road', as we're still just  working with the cement blocks, and 
are having to wait for warmer weather so the  concrete doesn't crack while 
curing.  
 
It seems the more I learn about SB building, the more questions I  have.  My 
wheels in my head are turning...hear them squeak?
- Kathy
p.s.  Frank, I looked at your website, (awesome!) ...and now I have  even 
more questions!  (more to come...)





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