On Thu, 3 Jun 2010 21:40:02 -0700 (PDT), Keefiedee
wrote:
Also, there is a piece of
window beading which has rotted and affected the wood underneath it.
When I replace the beading, I will need to build up the wood
underneath it with filler, but presume that the filler will stick to
the new beading, so that if I ever have to replace the glass the
beading will be firmly attached to the window frame and I will have a
devil of a job getting it off. Any tips on how to stop that
happening?


Remove the beading. Fill underneath. Wait at least 20 minutes for
the filler to set before fitting the new beading, and the beading will
not stick. Simples.

I suggest that you need to do a little more than just fill the areas
that have rotted. There is a very good product called Ronseal Wet Rot
Wood Hardener which does exactly what it says on the tin. g

http://www.ronseal.co.uk/products/wet-rot-hardener

Make sure that you remove as much of the rotten wood as possible -
preferably all - then use this product on all the wood surfaces that
you have exposed. It stops the rot and ensures that any filling you
do subsequently will not be threatened by any rot re-starting in the
surrounding wood.

I used this product quite a few years ago in a very similar situation
to yours, and the repair has worked perfectly, with no sign of any wet
rot returning.

It is very important to get out as much of the rotten wood as
possible, because the product's ability to penetrate and cure rotten
timber is inevitably limited to a small number of millimetres.