Sealant on wooden framed double glazing

[Monkeytennis]

I wondered if anyone had any advice on the following. I remember seeing somewhere that it was a good idea to put a bead of silicone sealant on the outside of the window around the edge of the glass and the frame, as shown in red in the picture:

The objective being, I think, to prevent water from getting into the frame. I'm not sure what is used in the construction of these windows between the glass pane and the wooden frame, but in some windows it appears to be starting to break down:

My first question is whether it is a good idea to apply the silicone sealant as mentioned and if so, should it go just along the bottom or around the whole window.

My second question is that on some windows we get a reasonable amount of condensation inside and so the same problem is possible, though to a lesser extent, i.e. condensation dripping down the window and into the frame below. Again on some windows the substance between glass and wood appears to be deteriorating:

My second question is whether it is sensible to apply the same process on the inside of the windows, e.g. clear silicone and again, if so, whether to apply just at the bottom or around the whole window.

Very grateful for any opinions on this.

 

[Gazman16]

Those windows are not really made correctly to take double glazed units, No drainage or ventilation.
So what ever you do it wont make the glass units last longer but it would help to protect the wood windows.
I would personally seal the outsides bottom and sides, and the insides on the bottom to protect the timber.

As and when the glass units mist up you may want to consider new windows too as the life expectancy of a glass unit in those windows is probably only 1-5 years especially on south facing windows.

I would masking tape up the glass and frame before sealing so you get nice clean lines. Use clear LMN silicone (low modulus, Neutral cure)

 

[Monkeytennis]

That's very helpful, many thanks. Good tip about the masking tape too. Cheers.

 

[ronniecabers]

That looks like putty to me , that has cracked over the years . Its no longer used for glazing sealed units into wood due to it deterioating ( can't spell today lol! ) sealed units in wood can and should last longer than five years if glazed correctly ..we offer a five year warranty as standard in wood frames we've glazed. But back to your problem , yes silicone with neutral cure as Gazman says .... if they are already misting up though , you won't stop them , they will just get worse

 

[Monkeytennis]

Yes, could well be putty as the windows are fairly old as far as I know. My main concern (which I forgot to explain in the original post) is the frames, but obviously misted units are not good either and we've had a couple go over the last few years.

 

[Gazman16]

That looks like putty to me , that has cracked over the years . Its no longer used for glazing sealed units into wood due to it deterioating ( can't spell today lol! ) sealed units in wood can and should last longer than five years if glazed correctly ..we offer a five year warranty as standard in wood frames we've glazed. But back to your problem , yes silicone with neutral cure as Gazman says .... if they are already misting up though , you won't stop them , they will just get worse

You guarantee them for 5 years into un-vented and non drainage frames? Who is your glass supplier?

 

[ronniecabers]

Used to make our own , until we just became un competitive due to the licensing ( bsen 1279 ) ... we held all the licences just werent really seeing our mone back. We did my wifes nans place 10 years ago and not one unit has broken down! These days we purchase from Premierdgu in Exeter

 

[ronniecabers]

Too be honest Gazman ...it is down to how they are glazed and whether moisture can actually penetrate the unit .. replacing sealed units in wood is one of our busier sides to our company as very few still do a good job!

 

[Gazman16]

I do it occasionally but my supplier only guarantees them for 1 year in incorrect frames, Not that they would question a few replacements unless it was alot.
Not that I have had any break down since I set up on my own 8 years ago