Converting old sash windows to double glazing, possible?
William
posted on 19-11-06
I had to replace a pane of glass in my old, draughty, timber sliding sash and case windows the other day. ( small boy with marbles)
It made me wonder if I could simply replace the glass with a similar sized double glazed unit. I mentioned this to my glazing supplier and he just said "no" it wasn't possible.
I don't see why not.
The minimum thickness DG unit is 14mm; 4mm glass, 6mm air gap and another 4mm glass. This would (just) fit into the existing rebate in the window. I'd need to use a wooden bead rather than putty to hold the glass in but so what? Also the DG unit would be a lot heavier so sash weights would need to be increased, or just left as is, since most windows in the house are rarely opened and closed regularly.
The results would be a lot warmer than currently and a lot cheaper and greener than scrapping the old windows and installing new DG.
I'm wondering , has any one ever tried this or can any one offer advice and/or comment on the idea? Thanks.
Ev
posted on 19-11-06
Why not stop the sashes fromm being draughty?
Tony
posted on 19-11-06
You would save far more by getting rid of the draughts. Do s aearch of the site for this it has been covered recently. But you are right about the dg units; though what you propose is not as straight forward as it may seem.
William
posted on 19-11-06
Ok , thanks,
I'll look into draughtproofing. I could not beleive the huge cooling effect which the small hole in the window had on the bedroom so making the windows tighter makes good sense.
My main reason for wanting to go double glazed is to get rid of the depressing, condensation soaked ( or ice bound) windows and cills which greet us every morning from this time of year untill May.
Biff
posted on 20-11-06
Your first plan, William, can work, and there are limits to the usefulness of draughtproofing. Insufficient ventilation can lead to increased humidity, condensation, mold, spores, asthma, suffocation, death....
Depending on the size of the sash you might get away with 3mm glass, allowing room for a bigger air gap and less weight. It won't be so strong or small boy's marble proof but 18th and 19th century windows are typically 3mm. If that's more of an issue than cost you could use toughened glass. If there's insufficient space for bigger weights change the iron weights for lead. It's tricky, but not impossible.
Loz
posted on 20-11-06
Most glazing suppliers will only 'ok' what they know (sometimes frighteningly little). There is no reason you could not have the windows draught proofed and fitted with double glazing units so long as there is enough room in the rebate to house the glass and the means of fixing as nailing beading onto the inside face will prevent the window from opening at all! The glazed units often come out fairly easily from the assembly and could be modified with a router to deepen the rebate, thus allowing enough room for glass and fixing.
