Do I replace my 20 year old double glazed windows, or just the misted units?

[alanalan20]

Looking for some assistance please.

The house we have is about 20 years old, but "new build", we have around 15 windows in total, which are made of wood but do have double glazing units within. I can see the gap between the window pains in the DG unit is small when compare to current standards.

Some of the rooms in our house are quite cold and I'm just trying to improve the situation. My questions are:

1. The sealed units that are misted up, is it worth just replacing the units or the whole window? All the wooden frames are actually in good condition.
2. Roughly how much does it cost to replace a pain like for like?
3. If I replaced all the windows with uPVC would I "see" a marked improvement over the existing wooden DG windows, in terms of energy efficiency?

Thanks

 

[dishman]

The payback on going from single glazed windows to double glazed windows is about 25-30 years. By that tiime you will probably need to replace them again. In reality it is not a very cost effective energy saving option no matter what the TV ads say. So going from even old/poor double glazing will not make economic sense.

If the frames are sound then I would look at replacing the glass only. However I have heard that using linseed putty for wooden windows can degrade the seal on double glazed units and make the fail earlier than normal. An alternative to linseed putty may be available, probably just a silicone sealant but I am not sure.

How many have misted up?

If however you are doing it for aesthetics/convenience then that is a different matter.

Personally, if you replace the pane, then I would look at all the other draught proofing options. Do the openers have good seals/draught excluder? Do you have good loft insulation? Cavity wall insulation. Have you fitted good seals and draught excluders around doors.

All those things will save you a lot compared to ripping out perfectly serviceable windows. Don't forget to give the frames a good coat of paint/varnish!

 

[alanalan20]

Hi

6 of the windows have misted pane's, the problem I also have is one of the windows (a bay window) is at the front of the house, if I change this to uPVC then it's going to look different to the window directly above... which is wooden and not misted.

Decisions, decisions.

If just asked for two quote, one from a UK wide dealer who advertises on the radio and TV, they average £770 per window. I also asked a local window shop, just two guys but loads of good customer reviews, they quoted and average £350. I just need to check the spec is the same.

Is there anything I need to look out in terms of spec is I do change? is Argon gas a must? I'm assuming I need A rated windows etc

 

[cheradenine]

FWIW - I found this site: http://www.sealedunitsonline.co.uk/ to be quite informative when trying to find out what the actual glass should cost (including "heritage" thin units, as thin as 10mm) which may help your decision. I was surprised how cheap the actual glass bit really is. (I have no connection with them nor have I used them myself).

'U' values improve once you get beyond the ultra-thin, but it's (IMHO) really small margins. E.g: a 10mm pane has a U-value of 1.9, but a 32mm (6/20/6) unit is only 1.2 - so on a really cold day if you were trying to maintain a 20 degree temperature difference from outside, you'd only be saving 14W (glazing bit alone; the frames are a different story).

If it were me, I'd measure the glass & thickness and just replace the sealed unit. For replacement the local window shop doesn't sound bad, provided you like the actual windows!

 

[dishman]

I am getting a misted pane replaced in my 20 year old UPVC bay window. I considered warms spacer bars and argon etc. but the gains will be minimal. Especially if the frames u-value will not up to modern standards.

I would be tempted to go for a like for like. Then concentrate on ensuring all the openers have good draught proofing and seals.

My post is just a few further down. I decided to go for a standard DG unit in the end. I am only replacing one however. As timber frames can be more succeptable to units misting up it may be a false economy to go for a top spec argon double glazed unit.