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Insulating void left by replacing pulley windows

brooklynite2 | Posted in General Questions on

I posted here a year ago about replacing original windows in a landmarked Brooklyn house:
(btw, my old account has been corrupted somehow; I’d love to get some tech support)

A year later, we have closed, moved in, gotten permits, and fabrication has begun. The new windows are double-hung (the landmark commission won’t allow anything else) wood windows by Pella. 

I asked my contractor (whom I love so far and seems very knowledgeable) about what will happen to the compartments within the frames that currently house the pulleys and weights. His response:

The weight pockets on the 1st floor windows will be removed and blocked out so that will be taken care of. For the windows on the 2nd and 3rd floor, we can add insulation and flashing tape to seal off drafts. 
His response indicates a design difference between the 1st floor and the others that I’m not aware of, so I’m trying to figure that out. That question notwithstanding, does his approach sound right? Any thoughts on what insulation materials should be used?

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  1. Expert Member
    Michael Maines | | #1

    I'm curious about the different approaches your builder plans for different floors, but it probably has to do with scope of work--removing finishes in some areas but not others, etc.. One-part canned foam is the standard these days for insulating the gap between windows and framing, but in an airtight cavity, fiberglass, mineral wool or other fluffy insulation would work just as well. Flashing tape will help make the cavity airtight. If they are using canned foam, everyone learns the hard way not to overfill the gap, or the expanding foam will bow the windows.

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