Hi,

Outside my knowledge base :-))

Several windows have developed cracks in the panes over the past year.
These have all been to the front of the house which faces roughly
north west. The windows have metal frames fitted into wood, the house
was built in the 30s. Nothing has hit the windows apart from the
weather.

Any suggestions as to the likely cause of this? Could hardened putty
be a factor? Just seems odd but outside my experience growing up
when nothing like this happened to my parents windows.

TIA

Jack wrote:
Hi,

Outside my knowledge base :-))

Several windows have developed cracks in the panes over the past year.
These have all been to the front of the house which faces roughly
north west. The windows have metal frames fitted into wood, the house
was built in the 30s. Nothing has hit the windows apart from the
weather.

Any suggestions as to the likely cause of this? Could hardened putty
be a factor? Just seems odd but outside my experience growing up
when nothing like this happened to my parents windows.

TIA
If they are Steel - (Crittal) then any rust forming will occupy more
space than the steel and put point pressure on the glass causing it to
crack. As to what to do - eitherremove the glass and clean and
rustproof the frames before re-glazing or replace the frames. IIRC from
a Grand Designs these can be converted for double glazing at a price

Malcolm

Jack wrote:
Hi,

Outside my knowledge base :-))

Several windows have developed cracks in the panes over the past year.
These have all been to the front of the house which faces roughly
north west. The windows have metal frames fitted into wood, the house
was built in the 30s. Nothing has hit the windows apart from the
weather.

Any suggestions as to the likely cause of this? Could hardened putty
be a factor? Just seems odd but outside my experience growing up
when nothing like this happened to my parents windows.

TIA

Jack,

There could be several reasons such as rusty frames (galvanising breaking
down), screw heads rusting [1] (under the putty), metal clips that holds the
glass in position rusting [1] (they take the place of tacks used in wooden
frames), temperature variations (especially if the glass is a 'tight fit' in
the openings, open sashes twisting and being put under pressure when closed
and a multitude of other things that could cause the glass to 'ding'.


[1] As they rust the metals expand and cause pressure on the glass - even
though all the frames, clips and screws would have been galvanised when
originally fitted, this can (and will) break down over the years causing
such problems.

Sorry I can't be more specific (I'd have to see them for that) - but from my
experience of repairing these things, I would suggest that if you are
starting to have these problems then it may be time to think of replacing
them - and you will certainly benefit from reduced heat-loss in the winter
(I certainly noticed the difference when I did mine way back in 1990 both in
temperature and cost during the winter months).

Cash

On Mon, 02 Aug 2010 21:00:22 +0100, Malcolm wrote:

. IIRC from
a Grand Designs these can be converted for double glazing at a price

Malcolm


Thanks for this.

http://www.channel4.com/4homes/on-tv...ay-09_p_1.html

The company referred to is

http://www.slimliteglass.co.uk/home.html

It is due to rust.
Use 3M Clean-n-Strip discs & "sandblaster attachment for a pressure
washer, then ideally a zinc rich epoxy primer.

The only other cause is the frames being crushed by load from above,
cracking the glass, but that is less likely.

Malcolm wrote:

Jack wrote:
Hi,

Outside my knowledge base :-))

Several windows have developed cracks in the panes over the past year.
These have all been to the front of the house which faces roughly
north west. The windows have metal frames fitted into wood, the house
was built in the 30s. Nothing has hit the windows apart from the
weather.

Any suggestions as to the likely cause of this? Could hardened putty
be a factor? Just seems odd but outside my experience growing up
when nothing like this happened to my parents windows.

TIA
If they are Steel - (Crittal) then any rust forming will occupy more
space than the steel and put point pressure on the glass causing it to
crack. As to what to do - eitherremove the glass and clean and
rustproof the frames before re-glazing

And using the correct metal casement putty
http://www.thesteelwindowcompany.com/Maintenance.html
see bottom of page
\0

On 02/08/2010 20:39, Jack wrote:
Hi,

Outside my knowledge base :-))

Several windows have developed cracks in the panes over the past year.
These have all been to the front of the house which faces roughly
north west. The windows have metal frames fitted into wood, the house
was built in the 30s. Nothing has hit the windows apart from the
weather.

Any suggestions as to the likely cause of this? Could hardened putty
be a factor? Just seems odd but outside my experience growing up
when nothing like this happened to my parents windows.

TIA

I once had a 1930s maisonette with crittall windows that were very
rusty. I raked all the old putty out and replaced it, treating the metal
etc. All looked good.
Sitting in the lounge some while after and heard a faint ping. One pane
had cracked. This went on intermittently until I had to replace a number
of panes.
Metal expands and contracts quite a bit with heat and cold.
Glass I understand is a supercooled liquid rather than a solid and it
gets more brittle with age.