Problems with a wood window frame.

I'm not sure if it's a construction or painting issue but I'd like a more long lasting solution.
It's a purpose built 2nd floor window which is approx 11 x 7ft consisting of 15 2ft square double glazed panels. The frame work is made from 3 3/4 x 1 3/4" throughout and is load bearing - the flat roof joists are in part supported by it. The glazing is secured by planted on beads on both sides - which I think are stop beads as used on a sash window.
Access is difficult as it's above a conservatory so requires scaffolding. It faces south so gets hit hard by all types of weather.
I've painted it myself and had it done professionally but the results are the same - it looks scruffy after only a couple of years. And the glazing beads need replacing through rot after 5 or so. The main structure seems to be ok.
So is there a better design of bead that would have a longer life - perhaps a better wood than my local yard supplies as a stock moulding or even PVC? It's worst on the bottom rails where the water must lie and get under the paint.
Last time I replaced the beads I soaked them in Cuprinol for some time before fitting but after cutting to size - but this doesn't seem to have extended their life or done anything for the paint adhesion.
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Hi,
Were the beads primed all round (on all faces) and particularly the end grain, before fitting?
Also can you remember what primer and topcoat was used?
cheers, Pete.
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BTW I think that aluminium bead would be a good choice for the bottom bead, with cutouts to drain any trapped water.
For paint I'd look into Sadolin Superdec/Woodshield which comes in satin or gloss:
<http://www.sadolin.co.uk/homeowner/products/garden / superdecopaquewoodprotection/description>
cheers, Pete.
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I can't really say about the original installation as it was painted by the builders - but was when I did it subsequently.

I've re-done it 3 times and a pro once. I've had Wicks, B&Q and Dulux wood primer (pink) around at various times and it will be one of those. The undercoat and gloss will have been similar. I've not noticed much of a difference in life with any of these. The pro seemed to swear by Dulux. His efforts have lasted less well than mine. ;-)
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Fair enough, I'd try the Sadolin stuff I mentioned in the other post, they have a product data sheet for download which has some good tips.
It looks like it's basically a water based opaque wood stain so works differently from normal oil based primer/topcoat paints.
When choosing a wood preservative, it's worth doing a little research on the active ingredients as some are better than others.
cheers, Pete.
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Dave Plowman (News) wrote:

I think I'd be looking for a pvc moulding. Any wood in that small a section is going to rot pretty quickly. You're presumably not that bothered about the profile, as long as it's wide enough to hold the glass and fix easily to the frame. A 15mm scotia maybe? What trade uses that kind of thing? Flooring?
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I was hoping there might be a suitable material that wouldn't need painting - but the original bead is shaped like a P where the leading edge goes to the glass - so will hopefully help to stop water getting into the join between it and the sill. And would an alternative to wood - PVC, ally etc expand and contract differently so just allow bigger gaps to develop? Or could it be set in some form of pliable gunge like silicone?
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Beads... a) Dulux Trade Preservative, blue cobalt/copper smelly muck b) Hardwood shaped to suit c) Use putty compatible with your glazing
I would find a putty compatible with your glazing and use... a) Dulux Trade Weathershield Preservative / Undercoat / Topcoat ---- wide choice of colours, choose white ideally re life ---- best looking Year-1, not as good Year 3+ ---- flakes off, requires stripping/sanding as not overcoatable b) Sikkens Preservative / Onol / Rubbol AZ ---- choice of colours is minimal ---- not as good looking as Dulux Year-1, better Year 2-6 ---- overcoatable paint which chalks
Akzo Nobel (Sikkens) have bought ICI Paints as I recall, so watch for smelly-good replaced by eco-water-based.
Sikkens Rubbol AZ is a gloss, Satura is the Satin. It is the most violently smelly paint you can imagine. It does not spread well, requires a synthetic brush and the film thickness is quite critical to get the full lifespan. Can be overcoated about 4-5x (about 20-30yrs or so).
Sikkens Rubbol BZ requires *perfect* wood or it will tend to not adhere, this is very true for hardwoods.
Sikkens Onol Express is the fast-dry low-temp undercoat.
The longest life paint is I think Permaglaze MVP, the next best is Sikkens. Can not recall if the Permaglaze is overcoatable, it may be the scrape/sand off (tedious).
We are South facing and whilst that means minimal heating is required, paint takes a lot of heat baking. Sikkens Rubbol seems to weather the best, although removing windows & painting horizontally is cheating.
Stainless steel hinges are your friend, 2" are available if you hunt them down and suit windows 1940s-on.
Wooden beading never lasts unless Cuprinol Duckback, which is more for sheds - although they do a "cream"? Putty on the other hand allows windows to survive even left-to-flake completely (ok, kiln dried wood). Radius corners properly - for Dulux W especially.
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Dear Dave There is no point in soaking in cuprinol and then cutting
Best is to use a grade 5 durable timber as described in the BRE Digest on porosity and durability eg iroko teak etc provided it is heart wood or if using softwood make it Scots pine and cut it all to shape first then double vac treat it If not double vac treat put each end grain in liquid , preferably, overnight (min 60 mins) mount in non setting butyl or similar mastic used for double glazing
On the sills and sub sills make sure there is a 10 degree slope and drip groove
I completely endorse all the other posts with reference to Weathershield primer ( Dorothy Bradbury) ( but not the specification of "hardwood" - Balsa is one!) and decent arrises (10mm for sills) and I recommend the Dulux OS paint system FOLLOWED by a coat of Sikkens Water repellant preservative stain which I put on every two years leaving the gloss underneath. The advantage is that it fails by chalking and you need no preparation when repainting I appreciate that with the conservatory below this is difficult but would recommend either a purpose built access or opening window
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That's why I cut them first then soaked. As I said. ;-)

Problem is all I've seen is the one type of moulding on sale - both in the sheds and Travis Perkins. No idea what the wood is. It seems closer grained than the ordinary stuff you get, though. The original stuff was fitted under the supervision of the architect who designed everything - but it lasted no better than the stuff I replaced it with. So where do I buy this sort of spec timber?

I wondered about that. The sill is a standard hardwood moulding of the type most yards sell. The other two horizontals are just plain PAR - so no slope. And the planted on bead has no slope either.

Right.
To alter the design would be extremely expensive - as I said it is load bearing. And it goes from floor to ceiling so a conventional opening window - or at least anything big enough to give access to the outside would be plain dangerous. At the moment there are three top hung opening panels.
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On Sun, 04 Nov 2007 13:39:48 +0000, Dave Plowman (News) wrote:

=================================Use a beading made from ordinary softwood. Paint each piece fully (use something like the Focus equivalent of Sadolin - appears to be better than Sadolin) before fitting. When fitting, apply a generous bead of ordinary frame sealant on all inner surfaces of each piece (including ends) so that it squeezes in / out to fill all cavities. Overpaint with same as originally used when the frame sealant has skinned over.
If you can make your own beading consider making one that projects (by about 1/4") beyond the beading reveal - effectively creating an all round drip. I used this method when making my front porch about 5 years ago and it hasn't required any treatment since.
For access see here for a cantilevered access platform:
http://i181.photobucket.com/albums/x223/coldpics/DSCI0012.jpg
Cic.
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