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Re: Glass Cracking

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Roger Turk/Jeff Smith,
investigating defects related to custom wood windows some years ago, I recall a
similar problem where the workmen (attempting to comply to California's Title
24)
implemented an aerosol, injected foam insulation which, when misapplied, created
significant pressure between the window frame and rough opening. Not only did
the wood sashes get stuck within their frames, but glazing also cracked on a few
windows.
This is just one possible cause of unusual glass cracking.

Steven A.
Los Angeles

Jeff Smith wrote:

> Roger,
>
> You might look into Stevens comment about the insulation. I have also heard
> of people using the foam insulation around window RO's, the foam can create
> enough pressure to cause problems, good intensions gone wrong. What kind of
> windows are they, wood, vinyl, aluminum? If you find out, you try a google
> search for known problems. What kind of glass is it?
>
> jeff
>
> > -----Original Message-----
> > From: Roger Turk [mailto:73527.1356(--nospam--at)compuserve.com]
> > Sent: Saturday, August 24, 2002 8:53 AM
> > To: seaint(--nospam--at)seaint.org
> > Subject: RE: Glass Cracking
> >
> >
> > Jesse and Jeff,
> >
> > Jesse, I don't know if the glass is encapsulated (sealed) with
> > gas between
> > the two panes.  I think that it is just a double pane window with
> > the panes
> > separated by a gasket, at least that is what it looks like.
> >
> > Jeff, the perplexing (to me) part of the crack is the parabolic
> > shape.  If
> > there was racking, I would expect the crack to be diagonal, e.g.,
> > failed in
> > diagonal tension, a la concrete shear cracking.  I also don't
> > know if there
> > is a laminate applied to either pane.  The upstairs window is
> > about 3' wide
> > and 4' high; the first floor window is about 4'wide and 5' high.
> >
> > There are workmanship problems regarding windows in the house.
> > The bottom
> > sliding sash of a double hung window in a bedroom had fallen out
> > of its frame
> > and has been replaced but there is still an indication that the
> > jamb is not
> > plumb in that window --- a wider side gap at the top of the moveable sash
> > than at the bottom.
> >
> > The homeowners, who are not the original owners, fortunately were able to
> > obtain copies of the county's approved plans just before the plans were
> > scheduled for destruction and are trying to get additional
> > information on the
> > construction of the house.  I have made only an initial inspection of the
> > house and don't know how far the homeowners want me to go with the
> > investigation, or even if they want me to continue with an
> > investigation.  If
> > I do continue, your comments will be considered.
> >
> > Thanks for your comments, an I welcome any other thoughts, comments, or
> > suggestions from the knowledgeable people on this list.
> >
> > A. Roger Turk, P.E.(Structural)
> > Tucson, Arizona
> >
> > Jesse D. Moore wrote:
> >
> > . > Could it be gas expansion between the panes?
> >
> > and Jeff Smith wrote:
> >
> > . > How big are the window and are the headers supporting floor
> > and roof load,
> > . > are there point loads over the windows? Any recent impact
> > loads? You said
> > . > no signs of distress, maybe do a water level survey, check all doors
> > . > windows and cabinets for square/plumb. when was the house
> > last painted has
> > . > there ever been any leaking i.e. shrink swell cycles? You may need to
> > . > remove the trim to see how it was installed. Check for equal
> > diagonals of
> > . > the window opening for racking. I am sure you have thought of numerous
> > . > possibilities:
> >
> > . > header deflection
> > . > wood shrinkage
> > . > maybe they were installed too tight with no shim space for the rough
> > . > opening.
> > . > some windows have receiving channels for deflection space and racking
> >
> > . > Jeff
> >
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