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exterior storms...tight or with air gaps?

Posted by bungalow_house (My Page) on
Sun, Sep 20, 09 at 12:24

We just had some wood storms made. The guy who made them insisted that we need to leave 1/8" gaps on all 4 sides. The guy who installed them insisted that they needed to be tight-fitting, otherwise they were useless. (Of course the guy who installed them won because he did it the way he thinks is right.) I have researched this and can't find a conclusive answer. I guess that means there isn't a conclusive answer and I will just shrug my shoulders and say "we'll see".

But I'm curious what others here think...should they be tight to seal in as much warm air as possible, or with gaps for expansion and to allow condensation out? I should add that they have removable panels for screens and glass, so while they hang on hangers like traditional wood storms, we don't really need to take them on or off the house except for occasional painting. And our windows have been recently restored and weatherstripped so energy efficiency with the window sashes themselves is pretty good already.

Follow-Up Postings:

RE: exterior storms...tight or with air gaps?

The 1/8 inch gap is to allow the application of weather stripping on all sides, not to allow for different coefficients of expansion. There should be weep holes at the bottom of the window to allow run-off of condensation.

RE: exterior storms...tight or with air gaps?

The guy who built them specified adding a vinyl gasket strip to the top but not the sides. And that was for a bit of insurance against water infiltration, not air.

RE: exterior storms...tight or with air gaps?

The gap is so they can be painted a couple of times, and not swell up so much that they can never be removed. If you need them tighter, apply weatherstripping to the top and sides, never the bottom, the moisture needs to escape someplace.

RE: exterior storms...tight or with air gaps?

Storm windows work by providing a space of dead air. That dead air acts as insulation. You don't want breeze blowing through the storm windows.

You do need a place at the bottom for any condensation to leak out. Warm, moist air from your home will get out of your interior windows. When that air hits the colder outer pane, any moisture will condense. It needs to be able to drip out the bottom or it will end up rotting the wood.

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