Replacing panes of glass

[Nicole W]

Hi All

Advice appreciated...

We have a couple of cracked panes of glass in some windows. We also need to replace a lot of putty in other windows as they're getting rather old and falling apart. We were wondering if it's worth (cost and effort) replacing the glass with new-fangled K-glass or thicker glass. All our windows are single glazed and we have no secondary or double glazing, which makes our house somewhat chilly in the winter. We don't live in a listed building but we are in a conservation area, does that make a difference? If anyone thinks it's worth replacing the panes, any idea of cost?

Thanks

Nicole

 

[christianb]

Hi Nicole,

Alas, I'm no big fan of double glazing, and particularly not in old buildings. To me it's an alien concept. In fact, I went into an almost identical cottage to my own recently and nearly expired through the clammy heat - they had installed double glazing, blocked up the chimneys, and had the heating on full bore. And then they had the temerity to whinge about damp and condensation.

Truth is, the vast majority of heat loss from a house is through the roof (and to a lesser degree conduction through the floor). What thickness of glass you can fit in the existing windows depends mostly on the glazing rebate. But, either way, restoring them will cost you a huge amount less than having refits.

C.

 

[Moo]

Single glazing and very thick (interlined) curtains is a simple and elegant solution.

If you don't want to replace your existing curtains, do what my mother did: she fixed an extra curtain rail behind the 'proper' one, stitched curtain heading tape to old blankets and in the cold months hung them from the extra rail. Worked a treat.

 

[Lime]

One of the most delightful aspects of old buildings is the glass.
It isn't flat, modern glass is.
Modern glass gives a totally different image to an old house so I don't recommend it at all.
Even likers of modern houses have said to me of their friends (who live in older houses) that they like the way the windows look because the glass isn't flat.
They called it character.

I think the idea of changing all the glass destructive.
It will give next-to-no benefit and will cause BIG problems if you have sash windows.
Modern glass is much heavier and will require all the counter weights to be increased in weight.
That will cause much disruption and damage.

 

[AMc]

We have a couple of cracked panes of glass in some windows. We also need to replace a lot of putty in other windows as they're getting rather old and falling apart. We were wondering if it's worth (cost and effort) replacing the glass with new-fangled K-glass or thicker glass.

Replacement double glazed windows aren't going to pay for themselves in energy saving for an incredibly long time possibly ever, assuming the frames you have are in decent or repairable condition.

Replacing the single glazing will have very little benefit , K glass may have a small impact but thicker glass won't have any & I wouldn't expect either to make a noticeable difference to the room temperature. Draft proofing you existing windows will probably make a much more appreciable change.

Reputtying, you run the risk of cracking old thin glass trying to put it back in. You need to remove the old putty as carefully as possible, watching out for the glazing pins embedded in there but be prepared for some losses and you'll end up with some mismatches. When our old Victorian frames were refurbished my decorator couldn't get the old 2mm thick glass back in, it simply cracked as it was pressed into the putty so we reluctantly fitted modern 4mm float glass into the old sashes.
To make life harder, modern float glass is thicker and heavier which means sash window weights have to be adjusted or they won't stay up.

 

[biffvernon]

To be perhaps a little pedantic, the density of glass has not changed over time to it's not really true to say that modern glass is heavier than old glass. The weight of a pane depends on it's thickness and in times of old when folk were poorer the thinnest glass that one could get away with was often used. It was sold (and taxed) by weight, 24oz to the square foot being a common standard, approximating to 3mm thick. 32oz was equivalent to the 4mm glass that is used as standard in domestic windows these days. You can, of course, still buy 3mm or even 2mm glass, though you may find that 4mm is cheaper owing to the ecnomies of its scale of production.

Hand made glass, whether cylinder or crown, was never a perfectly constant thickness and for pricing it was much easier to weigh it than measure the average thickness. Please do consider old glass in the same light as a piece of antique furniture or other historical artifact. It should be taken great care of. Crown glass in particular is quite irreplaceable as the manufacturing process has been lost and so it cannot be reproduced.

 

[Lime]

To be perhaps a little pedantic, the density of glass has not changed over time to it's not really true to say that modern glass is heavier than old glass. The weight of a pane depends on it's thickness and in times of old when folk were poorer the thinnest glass that one could get away with was often used. It was sold (and taxed) by weight, 24oz to the square foot being a common standard, approximating to 3mm thick. 32oz was equivalent to the 4mm glass that is used as standard in domestic windows these days. You can, of course, still buy 3mm or even 2mm glass, though you may find that 4mm is cheaper owing to the ecnomies of its scale of production.

Hand made glass, whether cylinder or crown, was never a perfectly constant thickness and for pricing it was much easier to weigh it than measure the average thickness. Please do consider old glass in the same light as a piece of antique furniture or other historical artifact. It should be taken great care of. Crown glass in particular is quite irreplaceable as the manufacturing process has been lost and so it cannot be reproduced.

I concur with your comments.

I would add that building regulations are usually the reason "heavier" glass is put in.
On an occasion a few years ago a glazier refused to sell me a thin pane of glass for a window because I told him what it was for.
Now, if I want thin glass, I say it is for my home-made greenhouse.

 

[christianb]

Please do consider old glass in the same light as a piece of antique furniture or other historical artifact. It should be taken great care of. Crown glass in particular is quite irreplaceable as the manufacturing process has been lost and so it cannot be reproduced.

Bang on. The old panes (including one with the original bullseye) in my own horizontal sash windows add so much to the character of the building and are priceless.

 

[Penners]

Single glazing and very thick (interlined) curtains is a simple and elegant solution.

Hear hear. And you'll get much better heat retention than you would by just putting in K glass.

As AMc says, you'd be better off just replacing the broken panes and then concentrating your efforts on draught reduction.