window insulation

With old man winter beginning to wake up from his slumber, I've been thinking alot about insulation for my windows, particularly the upstairs bedrooms. Currently I'm working on restoring the two side windows in my daughter's room. Since I can't just squirrel these away for a few weeks and work on them full on, the progress is slow. I'm just about halfway done with both of these. What's different about these windows is I did these the "correct" way. That is, removing old glaze then pulling out the glass to clean it. Sand the rabbet (the groove the glass rests in), then reinstall on a bed of silicone. Prime it, glaze it, paint it. So yeah, it's a thing of patience. My window of opportunity is closing (pun intended) so need to finish these up for the season.

The whole point to fixing these windows aside from the whole restoration thing is to make them airtight. Drafty windows suck -- despite their beauty, my wood sashes need some tightening up. The glass on these two windows was barely hanging on. Honestly I don't know how they didn't just fall out with our spring winds. I fixed the glass firmly in place and added some expanding foam in the crevices to the rear of the sill, then caulked the windows. But the windows were still draftier than I expected. A big reason for this is the gap along the parting bead where the upper and lower sash meet. See below.

I estimate I can eliminate 50 to 60 percent of the problem by fixing that gap. But what to use? I've been reading up on This Old House on how to tighten up old windows and one thing I've come across is the Easy Stop system. I'm very interested in that it just doesn't have some silicone strip you put on the bottom and top sash, but a replacement parting bead with insulation built in. I will be investigating this further and have ordered me a sample kit to see if it'll work for me.

In the above picture you'll notice the edge of a metal strip the sash rides on. You may recall I've referred to this stuff as sash rail. I'm not sure if it is original to the house but it does seem to be an attempt at insulation. Of course the bottom part of the sash has a groove that's pretty tight, but the upper part where the sash cord rests in has a significantly wider channel. It's here where we have a problem with air penetration. I'm not sure the Easy Stop will totally fix this (seems like a big gap), but I'm hoping it will. In the meantime I have a temporary solution to help stop the chill this winter..