Sash windows

[Wyabut]

Good morning all and thanks for adding me.

I live in a Victorian semi and am looking for advice as to what to do with our sash windows. When we moved in five years ago we had all the original sashes restored including draught proofing and all was OK. Five years on our road has become much noiser with traffic throughout the the night and with the two freezing cold spells, earlier this yeat, the bedrooms were really freezing despite having the heating on all day. The windows are still in good condition but do need painting again this year. I have read about removing the glass and replacing with double glazing but the results seem very mixed. So my question is has anybody successfully swapped single glazing to double successfully and does doing it eliminate noise, cold and condensation? I'm loathe to swap for upvc if it can be avoided but we do need to do something. Any advice would be really appreciated.

Many thanks,
Alison

 

[dandrew]

The limiting factor will be the width of the rebates in the sashes, as it will constrain the maximum thickness of glass/glazing unit that can be fitted.
A typical sash would be made from 1 3/4 " thick stock, which will finish about 1 1/2" when planed square. The average sash ovolo moulding was 5/8" wide, leaving 7/8" for the rebate plus mortice, -this means the rebate is usually shallow, at 1/4-3/8" (6-10mm). This is all the room you have to play with if you want to try and get a double-glazing unit in there which comprises a glass-vacuum-glass sandwich and will be on the order of 18mm thick or more (there are a variety of 'slimline' units available, but I doubt any are 10mm).

This leads to the following thought process:
Sashes too thin to get a double glazing unit in so I need to replace them
A thicker sash means I'll need a deeper box to accomodate them
That means I'll have to replace the whole window
How much is a new double glazed sliding sash window ?
Where I live 'oop north' a 1 over 1 sash that's 6 foot tall and 3 foot wide is about £1600 fitted

You can improve existing sashes with brushes and seals a la Ventrolla, which could help if they are a bit gappy, but an alternative is secondary glazing, which will allow you to keep your original windows and probably cut down the noise. I doubt it'll make the rooms any warmer as only 10% of a dwellings heat is lost from the windows (and double glazing will reduce that by half, which leads to an interesting calculation about the value of replacement windows in order to reduce heating costs and shows it to be a waste of money, burn the cash and at least you'll be warm for a while :mrgreen: ).

Perhaps not the answer you want, sorry.

David

 

[Penners]

An alternative idea might be to install secondary glazing inside the existing windows. This creates much wider gap between the two glazing membranes which is beneficial in terms of thermal and acoustic insulation - particularly if you line the space with acoustically absorbent material.

 

[Me!]

Or, have you considered adding internal wooden shutters?
They would make a big difference to both nighttime road noise and heat loss, and would be much more in keeping with the character of the building than changing to UPVC.

 

[MatthewC]

Is your Victorian semi listed? If it is then you are limited to adding secondary glazing and possibly the internal shutters. If it's not then you have the legal right to whatever you want, but I think most of us here would advise against the dreaded uPVC!

I think you should ask why the rooms are so cold. Do you have any loft insulation? I am convinced that the Thermafleece in my loft (all 300mm of it!) is why I feel the temperature increase as I go upstairs when it's cold outside.

BTW, as I understood it, you need a small gap in DG for thermal insulation, but the large gap with secondary glazing will cut out the noise better.

Matthew

 

[Penners]

Is your Victorian semi listed?

Not impossible, Matthew, but unlikely. A significant proportion of our Victorian housing stock is unlisted.

 

[plasticpigeon]

Also if you have any open fireplaces then these can allow a gale to blow through the room. When it is windy the wind howls under the front door of the house, then under my bedroom door and up the chimney taking warm air with it. When I put a chimney baloon up the chimney sealing it completely then there was so little air flow the room began to get stale. Interestingly I have sash windows, but they are well sealed as they have brush seals all round and only a very small gap at the meeting rail which must be less gappy than a trickle vent on modern windows. It seems the right amount of ventialtion is difficult to achieve. If your windows are letting out a lot of heat heat then seconary glazing works well. My sister has it in her house, and it doesn't look too intrusive and seems to work as well as double glazing.

 

[Feltwell]

Speaking as someone who lives in a Victorian semi with single glazed sash windows, I can only echo all the good advice given above. All I'll add is whilst you had your windows done by Ventrolla, did they do a good job? Their reputation is somewhat variable.

I've draught proofed my sashes myself, and it's definitely made a big difference both to how warm the rooms are and to the noise that comes in - but we do live on a quiet-ish road and they were very gappy indeed before. If you tried to put DG in then I think you'd be very disappointed with the results for the money you'd spend. Secondary glazing will be much more effective against noise, the bigger air gap between the panes makes a real difference, and even more so if the secondary glazing covers all the frame.

The problem with secondary glazing is making it look acceptable. It very much depends on the design of your windows and how they are fitted - if you've got a decent rebate on the inside to fit a secondary frame inside it can be quite unobtrusive, but I don't have that and I've now given up on finding a decent solution. I did try perspex and magnetic stripping for a while, which worked OK and was visually quite good but was such a faff to deal with huge perspex sheets when it came to wanting to open the windows in summer.

We had 2 seriously cold spells last winter, the heating struggled to keep pace here but in context that was 2 separate weeks where we noticed it in over 12 years of living in the house. Unless you've got huge gaps and howling gales around your windows currently - which it doesn't sound ike you have - I don't think changes to your windows will make that much difference to how warm your rooms are. Thick lined curtains are always a good idea though.

 

[Lostgardensof]

We have had double glazed glass fitted and it was not all that costly and did cut the noise down a bit. We could have gone for 'acoustic' glass which apparently would have cut it down more but we were mostly doing it to keep warm. You will need to replace the lead weights for heavier ones too to balance the new glass.

 

[Lostgardensof]

The units we have are 12mm deep.

 

[Feltwell]

We have had double glazed glass fitted and it was not all that costly and did cut the noise down a bit. We could have gone for 'acoustic' glass which apparently would have cut it down more but we were mostly doing it to keep warm. You will need to replace the lead weights for heavier ones too to balance the new glass.

Was that *just* DG though or did they fit draught proofing at the same time? Brush seals on the staff & parting beads and the meeting rail, and a bubble seal on the top of the top sash, (or similar) make a surprising difference to noise even without DG.

 

[88v8]

Histoglass can supply units 11mm thick. With wobbly glass. No way would I remove original wobbly glass.

They will reduce but perhaps not eliminate condensation. What's the rh?

But as to noise, they will do next to nothing. As has been said, for that you need secondary glazing. Up to a 4" gap will be beneficial. Beyond that, you will get thermocirculation that will leach out your heat. For best noise suppression, the glass in the secondary glazing should be of a different weight from the primary glazing.

Your increased noise arises from the UK's excessive and growing population; if we had zero net immigration and a significant fiscal disincentive for a couple producing more than two children, this would not be happening.

Ivor

 

[Lostgardensof]

Feltwell, we had the brushes fitted too so that will have contributed too.