I did receive full section details for all their window designs as well as the information on the glazing units I requested. I can't access all that right now, but from memory, the triple glazed units have a g value of around 0.63 which is pretty good.

That is good information to have, must remember when I go to build to consult here to see what hidden gems there are about. Why do these companies seem to hide so much and only the tatty manufacturers are easily contacted

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Dear God but that's a big hole Rick-M; now what? Perhaps you should get someone in to draught proof your sash windows....

Posted By: Rick_MThe draught proofing did make a huge difference, I was disappointed there were still these gaps on completion though. How has everyone else managed this section?

It looks like your parting bead is recessed into one of the sashes? That's not how mine are constructed and so it might be that others haven't had to deal with the problem. Sorry that's only an observation and not overly helpful!

As this thread is resurrected, I'll note on my first reading that no-one appears to have mentioned the issue of the sash window changing in weight if single glazed panes are replaced with double glazed ones.

It may be obvious, but before putting the heavier window back in the frame, it needs to be weighed, and the sash weights need to be replaced accordingly (half each side). If you're lucky, the weights were cylindrical within rectangular cavities, and you can get square section sash weights (lead) that you trim to length (for the desired weight). You can replace the cords as well while you're at it, and service the pulleys, etc.

There are suppliers who specialise in replacement sash weights for those into double-glazing them.

Beware that the window will have even greater mass/inertia, so can be more prone to slamming up/down, despite being balanced.

Posted By: crosbieAs this thread is resurrected, I'll note on my first reading that no-one appears to have mentioned the issue of the sash window changing in weight if single glazed panes are replaced with double glazed ones.

It may be obvious, but before putting the heavier window back in the frame, it needs to be weighed, and the sash weights need to be replaced accordingly (half each side). If you're lucky, the weights were cylindrical within rectangular cavities, and you can get square section sash weights (lead) that you trim to length (for the desired weight). You can replace the cords as well while you're at it, and service the pulleys, etc.

There are suppliers who specialise in replacement sash weights for those into double-glazing them.

Beware that the window will have even greater mass/inertia, so can be more prone to slamming up/down, despite being balanced.

Having recently broken one of my single pane sashes (1910 vintage), I found it reasonably straight forward to replace with double glazing if you have a router. Replacing the cords and "re-weighting" was also easy. if you fit brushes to the beading it provides a bit more friction to prevent slamming up or down, though if you fit lift handles, that's less of an issue anyway. I had zero experience with windows before this.