Chris Hogg wrote in
:


I suggest you post your question in uk.d-i-y. AFAIK, if you apply
preservative or paint, once it's dry it won't affect the PVCU.
However, neither will it cure wet rot. If you seal moisture inside the
wood then you may make any problem worse. So better to check with the
"experts" in the other group.

Cheers
Jake

Missed the OP, so replying via Jake's post.

We had UPVC soffits, fascias and barge boards fitted last year. Not
cladding. The old wood was mostly removed, but in one place, a gable
end, it wasn't possible to rip out the barge board, so they had to
clad the existing timber. They spent some time boring lots of large
(~30mm) holes right through the existing barge board, because they
said otherwise condensation builds up behind the cladding and the wood
rots. They said it was a common problem with simple cladding and
cheap-jack installers. Whether true or not I don't know, but I see no
reason why they should bother to do it otherwise. The contract was set
and they needn't have bothered; I would have been none the wiser.


My apologies I sent the original post to this group in error. I cancelled
the post almost within a few minutes, as soon as I realised. Anyway, thanks
for the input.

Chris: Your hole-boring info was of special interest I haven't heard of
that practice before. With the same end in mind, I was aready thinking of
adding some kind of spacers between the cladding and the fascia boards to
create a small (say 5mm) air space.

Al