# Old Single Glazed Sash Windows



## majee (3 Aug 2006)

ours is an old 3-story house which has single-glazed sash windows. We've done a lot of work to the house in the last few years and now it's time for the windows to be done. Is there anyplace out there that could do a restoration job i.e. dip them and then double glaze them or is this asking too much. Price will obviously be a factor. But I'd like to keep the windows we have if we can as they are a nice feature to an old house.


----------



## NHG (3 Aug 2006)

In order to double glaze the sashes you will have to replace the sashes as they are glazed with either 2mm (if very old) or 4mm glass and the minimum would be 14mm (4mm/6/4mm) for double glazing and it would be very surprising if the glass rebate could accommodate and extra 10mm.  The weights will also have to be adjusted as there is a massive difference in weight between s/g and d/g.

As each double glazed unit has 12mm of a black seal all around this would also need to be covered as it would be unsightly.  Your glass is probably held in place with putty which would need to be replaced with timber slips as the putty could react to the double glazing sealer.

If you have mullions (i.e. georgian bars) these will have to increase in size in order to cover the 12mm black seal that I mentioned above.

If you really do not want to change the sashes and would be happy enough to stay with s/g (& condensation) you could get a glazier to come and change the glass to 6.4mm laminated which would be much better than 4mm s/g but not near as effective or effective as a soft coated "low-e" D/G unit which could give you a U Value of 1.4 if air filled.


----------



## Diziet (3 Aug 2006)

Why double glaze the sashes? It is not worth doing unless you go for expensive sealing all round also. Plus, older houses are not supposed to be airtight and you will get damp problems. 

Just make sure you have your windows in good working condition and leave it at that. Lined curtains are as effective as double glazing. If you do manage to double glaze you also need to adjust the weights (your windows will be much heavier) or go for the less satisfactory spring loaded system... Don't go there!


BTW, I have th original sash windows in my house (single glazed) and went through all these options in the past. Please don't be tempted to put plastic windows in; they are horrible in an old house.

cheers,
Diziet


----------



## majee (3 Aug 2006)

thanks for the prompt replies! Rest assured we will not be putting in PVC windows. All our neighbours did it and lived to regret it. We have them in the back of the house which is OK as far as I'm concerned. But the front of the house is a different matter. As for the the house being airtight if we get D/G and thus get damp problems, there's plenty of other 'breathing spaces' within the house! By the sounds of things, a restoration job is probably out of the question in terms of D/G. However the condensation which NHG talks about does annoy me as you can get quite a puddle of it on the window shelf in the mornings.


----------



## S.L.F (7 Dec 2008)

Just came across this thread.

What they used to do in bygone days was open both windows a fraction in the morning for an hour or so to air the rooms, the way this worked was warm air would go out the top and cold air would come in the bottom.

Thus the room would be vented.

Regarding using a heavier gauge of glass than the original this would be fool-hardy as heavy glass installed will strain the joints of the sashes.


----------



## fuinneoga (7 Dec 2008)

I am at present investigating secondary glazing, which is , in effect, putting in another layer of glass inside the existing window. There are several ways to do this.
I see it is done in big old windows in institutions like churches etc. 
I wonder if this system is as warm as double glazing?  ( I dont want to throw out our old "picture" windows, which swing on a central pivot and were probably expensive originally.

Has anyone done it? What was the result?
The glass would be nearer to the room/ people/ children---any thoughts on possible breakages?


----------



## Gordanus (8 Dec 2008)

I was walking down a road recently with a terrace of old houses and noticed that many of them had operational wooden shutters on the inside of the windows.  I wonder if this was for insulation when they were first built.  It might be an option to get shutters fitted.


----------



## S.L.F (8 Dec 2008)

fuinneoga said:


> I am at present investigating secondary glazing, which is , in effect, putting in another layer of glass inside the existing window. There are several ways to do this.
> I see it is done in big old windows in institutions like churches etc.
> I wonder if this system is as warm as double glazing?  ( I dont want to throw out our old "picture" windows, which swing on a central pivot and were probably expensive originally.
> 
> ...



I've seen secondary glazing in houses it tends to be very ugly to look at.

You could invest in heavy curtains, or get insulation blinds installed.

As far as I'm aware shutters were mainly for blocking the light out, security and not so much for insulation.


----------

