I have seen several articles about replacement windows where it is reccomended to stuff pieces of batt insulation into the widow weight cavity to insulate it. I have heard that this method is unreliable. Would it be better to drill a series of 1" holes in the jamb where it will be covered by the replacement and then fill the cavity with window and door spray foam? My second question is where can I get a reusable spray foam gun that uses the disposable cans of spray foam? Thanks,
Keith, do a couple of searches here. That topic has been discussed several times and has some info. Basically, ithe summayr is if you really want to be sure you should remove the interior trim and then you know that you have insulated the entire cavity as it should be. The other opionion has been that you do like you said, drill some holes and fill with the expanding foam. You may be surprised at how much each cavity can take if you use the foam. Remember that you are filling a cavity the thickness of the wall and at least 2 to 3 inches from window frame to the next stud or the brick.
I have done it that way and since the trim was not removed I really do not know how big the cavity was on this particular job. But we used 2 cans of the the Great stuff per side of the window. They were tall windows set into a brick wall so far all I know I may have been partially filling a void in the brick.
If you can you might try to take off the trim on one or two windows to see what is behind the trim. That would give you an idea of what could be back there. Then you could actually do a little experiment by drilling a series of hole in the widow jamb and filling the cavity to see how far you need to put the holes and get a gauge of whether it is effective to drill the holes 6 inches aprart or would 12 inches apart do the job. If taking the trim off is not an option you might be able to take the weight pocket doors off, look inside and get an idea of how much room is back there by looking in.