/ Sealing Wooden Windows

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A quick question for the UKC DIY expertise (can't find a convincing answer on YouTube):

I am working on my wooden windows and have to replace some of the wooden beading strips at the bases of several windows. In a lot of cases water has got down the back of these and rotted the main window frame below so I want to make a proper seal this time.

What is the best way to seal a beading strip? Some people seem to use putty, and others use silicone sealant. The former seems to me to be more long-lasting but harder to actually work and it inevitably dries and cracks anyway.

Thanks

Alan
woolsack - on 08 Oct 2012
In reply to Alan James - UKC and UKH: You can't get paint to stick on silicone
jimtitt - on 08 Oct 2012
In reply to Alan James - UKC and UKH:
In my previous life in a window factory we used mastic sealant tape and then a thin silicone bead over the top.
In reply to woolsack:
> (In reply to Alan James - UKC and UKH) You can't get paint to stick on silicone

No, that's true, but the paint only really needs to stick to the wooden beading, if the seal behind the beading is a good one.

The problem we have had with the current windows is that seal has corroded which has meant water has got down the back of the beading and rotted from within.

Alan
jon on 08 Oct 2012
In reply to Alan James - UKC and UKH:

Just did all our windows last month. I used putty. If most of the existing putty is OK and it's just the bottom of the pane that has dried out/cracked (as was the case with ours), then it's better to leave the glass in place and simply scrape out the the dried stuff and re-point it. It was quite easy to do. I wondered about the problem of the putty drying out - we're at 1300m and south facing - but the guy insisted that putty would be fine and would last at least 10 > 15 years. He said silicone would be rather messy... but that probably says more about me!
Hardonicus - on 08 Oct 2012
In reply to Alan James - UKC and UKH: Beading is just a cop out from a proper job with putty. The critical thing is to lap the paint over the putty and onto the glass by about 1/8th inch to form a perfect seal.

If you insist on beading strips I would have though loads of silicon bunged in is the way to go. Don't worry about the excess squeezed out on refitting the bead, just cut it flush with a knife once it has set.
In reply to Hardonicus:
> (In reply to Alan James - UKC and UKH) Beading is just a cop out from a proper job with putty. The critical thing is to lap the paint over the putty and onto the glass by about 1/8th inch to form a perfect seal.

Curious, the builder I spoke to the other day was all for beading strips over putty (I forgot to ask him about the combination). Also, it does look nicer if you have a nice tidy beading strip.

The other problem we have is that all the windows in the house have beading strips hence putty would look odd on selected windows, although not the sort of odd I couldn't live with.

Alan

jon on 08 Oct 2012
In reply to Alan James - UKC and UKH:

Sounds like you and Hardonicus are talking cross purposes? Have you got wooden glazing beads that were originally sealed with putty? Hardonicus seems to be referring to glazing using just putty and no bead.
Hardonicus - on 08 Oct 2012
In reply to jon: I was meaning if you do the whole window, just putty is the way forward. If beading I would just gunk loads of silicone in the back of it.

Putty lasts a long time, but requires you to keep up with you paint maintenance to stop it drying out and cracking.
Robboj - on 15 Oct 2012
In reply to Alan James - UKC and UKH: are your windows glazed with double glazed units? If so they should have been glazed with butyl putty as opposed to linseed oil putty for single glazing. Butyl is used as it doesn't set solid & crack. Also double glazed units should be set onto small glazing spacers to prevent the bottom of the unit from coming to contact with the frame which may contain moisture which rots the unit's seal (this is the most common reason for premature failure of a dgu's seal). The beading itself should also be bedded with butyl putty as opposed to just silicone. Silicone actually doesn't bond very well to wood anyhow. I was taught to always use mastic with wooden frames.
pork pie girl - on 15 Oct 2012
In reply to Alan James - UKC and UKH: just had ours done, used silicone
sealant
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MaxWilliam on 15 Oct 2012
In reply to Alan James - UKC and UKH:

If you don't use putty, an adhesive sealants typically used in marine environments (like Sikaflex) would be longer lasting than silicon. Obviously the wood beneath needs to have a low moisture content and should coated with an oil based wood preservative, else nothing will stick.

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