I need to somehow insulate/seal my single pane eyebrow window.

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Forum topic by Ben posted 01-08-2018 07:27 PM 447 views 0 times favorited 3 replies Add to Favorites Watch
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443 posts in 3308 days

01-08-2018 07:27 PM

I built this eyebrow dormer about 5 years ago and am now kicking myself that I didn’t make it with insulated glass. Back then I was a die-hard traditionalist.

Now I get a lot of condensation on the window trying to heat and humidify.

Some photos:

There is no way to remove the sash at this point without a lot of damage.

Would it make most sense to make to essentially build a duplicate sash using a single pane of insulated glass?
Installed on exterior? Interior?

Or just put some of that shrink wrap plastic window sealer stuff up on the inside for the winter?

I don’t want to lose the look on the exterior, but am willing to compromise at this point for my home’s efficiency.

Many thanks for any ideas.

3 replies so far

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John Smith

1921 posts in 614 days

#1 posted 01-08-2018 08:17 PM

Ben, just put some of that shrink wrap plastic window sealer stuff up on the inside just for this winter . . . . . .

then, crawl up there and take measurements (unless you still have the patterns you worked from),
and see if it is possible to cut pieces of glass the same size as existing and caulk them tightly in place
leaving about 1/8 – 1/4” air gap. purchase a can of argon gas and fill the air gap and plug with caulk.
it will be a tremendous pain working up in the air like that, but, unless you take it all down, you have
very few options.
If you can get an airtight seal with the plastic window seal-wrap, you may be able to shoot a can
of argon into the air space and it might work fine. for the price – it outweighs most other options.
I have no idea if argon can migrate through plastic film or not…..... (like helium does in balloons).
- or – can you cut a piece of 1/8” plexiglass to fit snugly within the frame? that would be less noticable.
also – the plexiglass would be soooooo much easier to cut, install and caulk than storm window plastic.
and my latest experience with the storm window plastic – IT SHRINKS !!!! so that would defeat your purpose.
argon is heavier than air….. so whatever method you choose to go with, the bottom must be sealed airtight.
a single pane window has an R-Value of .85, an argon filled double pane window jumps up to 2.7 – 3.6.

do the google search: WHAT IS BLOXYGEN

very nice craftsmanship on the window BTW !!


-- I am a painter. That's what I do. I paint things --

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443 posts in 3308 days

#2 posted 01-08-2018 08:44 PM

Thank you, John!

View patcollins's profile


1687 posts in 3316 days

#3 posted 01-11-2018 01:41 AM

There are two ways to prevent the condensation, either warm up the pane of glass or lower the humidity of the air hitting it.

Sometimes it only takes a small fan set on low blowing on the window to keep the condensation from forming, but this will increase the heat lost out of the window to the outside, but that is better than a rotted window frame from all the condensate on it.

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