"Martik" wrote on 07 Jan 2005:

To prevent condensate forming between the two panes,
do I need to air seal the two panes or just secure with a second
set of wood strips?

It's not that easy a problem.

Condensation forms in proportion to the humidity of the air and the
temperature of the surface.

If warm, humid air leaks through the new inner pane and gets to the
cold outer pane, condensation will form on the inside of the outer
pane.

If cold air from outside leaks through the outer pane and cools the
inner pane, condensation will form on the inside of the new inner
pane.

Most window makers make the seals airtight and fill between the
panes with an inert gas. That's a great solution, as long as it
works. Once the seals deteriorate and air leaks in, the window
clouds and the entire glazing system needs to be replaced.

Pella windows let a small amount of outside air between the panes.
That seems to prevent any condensation between the panes, but
doesn't allow the inner pane to cool to the point where indoor
humidity condenses inside.

So, to put it simply, you're trying to replicate the results of the
best window manufacturers and their labs in a jerry-rigged system.
The answer, I think, is that you won't be able to do so very
satisfactorily, and you'd be better off getting a real 2-pane
window and installing it.

--
Doug Boulter

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