I called a window guy to get a quote on something that will leak less
heat than the old single-pane windows that we have. I want dual pane,
low-e, argon filled Energy Star windows.
One of my ideas, on the non-operable (i.e. windows that don't open)
windows was to have interior storm units. It struck me that I have
plenty of space to put windows there, but he said that no, 2 inches is
not enough. All of the dual pane units made in Canada, he said, are
the same depth. I don't remember the exact figure he gave, but it was
more than 3 inches. I have that much space on the sill, but only a
touch more than 2 inches between the posts.
I'm wondering, is this provision of big frames from necessity (you
don't want the units leaking air in, because then the argon leaves and
you lose some of your insulation / noise reduction value, and risk
condensation), or from habit? Yes, I can see that it could be tricky
to devise a framing system which would keep the seal intact while the
unit was being installed (torque applied to the unit) or if it suffered
some trauma (like a ball hitting the glass, but with insufficient force
to actually break the glass), against temperature gradients, or against
differences in tension during installation.
He said there would be no problem fitting a *single pane*
exterior storm in the space available. If I want dual pane, low-e,
argon filled, he says it's likely that I have to replace the wooden
sash units with vinyl.
So my subsidiary question is: is there any sense in buying "naked"
dual-pane units and making wood frames (similar to picture frames) for
them myself? I repeat that I'm asking this only about non-operable
windows. Brief idea: drill hole at bottom of existing sash (to allow
air flow against condensation) affix good quality weatherstripping on
existing windows, place new unit in frame against weatherstripping, fix
in position (low compression), and seal any leaks.
What do you think? Likely to work, or likely to fail?