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Frank63
Expanding foam for Weight Pockets

We are replacing the original double hung windows in our 1920's house with vinyl replacements. The weight pockets are not accessable from the front wall (behind the moulding) so we are planning to use expanding polyurethane foam (think "Great Stuff") to fill the voids. We like the high R-value and the closed cell sealant properties. Does anyone have experience or opinions on this method of insulation? Advice on where to purchase in bulk or which products work best (we have 30 windows). Thanks.

A. Spruce
Re: Expanding foam for Weight Pockets

Don't just squirt expanding foam in through the pulley slot. Expanding foam creates hydraulic pressure great enough to distort or pop the window frames and casing. You don't want to create problems to deal with later. You'd be better off removing the trim from around the windows to apply the foam to the spaces. You'll get better filling of the cavities and your foam will go further (do more windows per can ). If too much is applied, it will have room to expand and can be trimmed off later before the moldings are reinstalled.

Just a note on expanding foam. A 1/4" bead will expand to over an inch, so you can see where overfilling a confined space will result in problems. :cool:

Ernie_Fergler
Re: Expanding foam for Weight Pockets

On the lower sides of the old window frame will be access panel. Said panel is usually held in place by a straight head screw.
Remove the weight in that panel because it is no longer in use.
Then use that opening to refill the pocket as well.

A. Spruce
Re: Expanding foam for Weight Pockets
Ernie_Fergler wrote:

On the lower sides of the old window frame will be access panel. Said panel is usually held in place by a straight head screw.
Remove the weight in that panel because it is no longer in use.
Then use that opening to refill the pocket as well.

In all my years I think I've only come across one house that had these access panels. I grew up in an 1800's era Vicky - no access. This might be a west coast thing, I don't know, but access is not always there. :cool:

mgrubb
Re: Expanding foam for Weight Pockets

30 windows, thats a lot. Ok, call an insulation specialist, someone that specializes in the expanding foam. There is a certain formulation that can be poured into existing walls. When it expands, it expands up, and does not apply great amounts of pressure on walls, or frames. I think this might be a perfect solution for you. Also, you don't need access. They drill a hole to insert their hose into and then plug it when done.

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