Window replacement – insulating weight pockets- please advise?
[9/9 update: I’ve visualized the window insulation as a picture-frame around the window: the window sits within an open wall (the wall is open attic to basement, left to right minus maybe fireblocks); the task as I now see it (at 2pm 9/9/19) is to fit into the sash-weight pocket Rockwool (still working on that install) and air seal the RO before I re-install the replacement window. It seems foolish to just stuff fiberglass up into the pocket and foam will be hard to contain in this assembly. Low expansion/pressure foam above and below complete the ‘frame’.]
I’ve had some difficulty with doing my first solo window replacement re: insulating behind the rough opening. This house is a 1917 single-brick veneer exterior, lath and plaster interior, the wall is (I believe) open from attic to basement. I discovered that there were sash weight pockets behind the RO. After removing the damaged plaster (see the photo below) I noticed that the pockets are open to the wall cavity.
In the Mike Sloggatt video on FHB, “Install Insert Replacement Windows in a Brick Wall”, it is advised: “If your window has weights, it’s a good idea to remove them and fill the window pockets with insulation.” What should be the approach here, to just air-seal the rough opening after filling the space with fiberglass or low-expansion foam as many recommend? My bet is that carefully feeding in Rockwool might work best as 1. compression won’t be such an issue, 2. I don’t have to worry about it flowing out of the pocket and 3. Rockwool tolerates getting wet if that happens.
Once again, any insights would be most welcome. Thanks. – John
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