The hardwood d/g windows in my 1993 house are showing signs of wear and tear. Some of the units (including the patio doors) are burst and condensate between the glass. I'm thinking towards the warmer weather and reckon that I'll need to replace the burst units. At the same time, a number of the other windows are leaking between the glass and the frame. I have resealed the leaking ones by running silicon sealant around the edges - which was a temporary solution for the winter. Now for the questions:

1. To stop the leaking, I need to take out the glass units. Should I use putty or sealant or something else when I refit?

2a. While going to the bother of taking out the glass - should I be replacing every unit or only the burst ones?

2b. What's best regarding replacement units from an insulation point of view. Presumably I have to stick with double glazing? I would prefer triple, but doubt if I can get something that will fit the existing frame.

3. If I get this done professionally (which I probably will), am I best to go the whole hog and replace the whole window (ideally maintenance free with UPVC)?

All advice welcomed. If it helps, I'm in a windy area on the coast and the room always feels colder when there's a strong wind. I blame the windows!

I know we are on a GBF, and so we ought to be thinking for the environment first. . . . .
BUT. . . . .

When my parents had their outbuildings turned into a kitchen 37+ years ago, they had DG units installed, and they had 'lino' stuck down to the concrete floor. . . . . . The lino was ALWAYS awful, because the firm stuck it down on a concrete floor which had dobs of blobs of concrete on the floor - so no matter how much it was polished, it always had lumps.. . . . .

The DG units ALWAYS had condensation between the panes - they tollerated it for LONGER THAN THEIR MARRIAGE LASTED. . . . . . When they got divorced, and the wooden frames were so rotten, the panes looked likely to fall out and crush someone. . . .that's when they were replaced.

I always tend to take a quote ( '£1,200 for new UPVC windows" and divide it by. . . . . . . . if it's a year, then these windows will cost me £100 a MONTH. . . . . . . .if it's 12 years, then it's so much less. . . . . . but then. . . are they guarented for 12 years???)

1. use a dry glazing system - this uses rubber seals instead of wet sealants. much more reliable and easy to maintain.
2. if a unit looks ok i would leave it, but be prepared to come back to it in a few years. probably a good idea to replace the beading and seals though.
2b. best double glazing uses soft coat low e glass (eg saint gobain planitherm), argon filled cavity, warm edge spacer.
3. This is what most joiners will recommend you to do because they don't like fiddly jobs like repairing stuff. So bear in mind that you're doing it for your benefit, not theirs and make up your own mind. If you do need to replace some or all of them, wood doesn't need to be much more expensive than upvc although the big companies will charge you an arm and a leg. Ask around here.
UPvc is not very eco friendly, not maintenance free and will not necessarily last longer than a properly made / refurbished wooden window. i would be interested to see any photos of your windows particularly the bottom and side beads. the windows could probably be refurbished fairly easily.

I can email you some informative e-books if you drop me a line on email.