Starting the window replacement on the 130 year old Victorian this coming weekend. (A total of 15 windows to replace over the next few weeks) The existing windows are wood sash in poor condition. The replacement windows are vinyl which we purchased from Lowes. (ReliaBilt I believe...) Now the question...
Before purchasing the windows, Lowes sent one of their people out to take measurements. What we have now realized, is that the measurements taken allow the vinyl replacement to fit in the space currently occupied by the wood sashes. Normally, I'm sure that this would work out just fine. Unfortunately, since we're dealing with old sash windows, we're also dealing with old sash weights. And more specifically, the hollow sash weight ports on either side of the window frame. This makes things interesting when it comes to screwing the vinyl replacements to the frame, no? If we simply pull out the stops, parting bead and sashes from the old window and then install and screw the new windows in place, the screws would be driven into the hollow weight cavity and therefore, provide little support. I didn't have a tape measure with me during the last trip to the house, but I estimate the depth of the sash weight port to be around 3". At the back side of each port is what appears to be the wall stud forming the "true" rough opening.
I don't feel comfortable supporting the windows with screws driven into the empty cavity. I'm assuming that I'll need to tear out the trim work down to the wall studs on each side and then "build out" a new rough opening to accept the vinyl replacement. I'm thinking two 2x's on each side should be enough to create the proper rough opening for the new windows. Any other thoughts on better ways to accomplish the window replacement? Should I just drive the screws into the sash weight ports and rely on my window stops to keep it in place? Am I over-analyzing this?