In article ,
Tim S writes:
Andrew Gabriel coughed up some electrons that declared:

In article
,
writes:

If you realy want to know which it is, this should clear it up:
http://www.wiki.diyfaq.org.uk/index.php?title=Wood_Rot

I presume that's meant to be a joke?

I took it to be, after the first couple of sentences. Sadly, it *is* an
accurate reflection on the results of earnest research into the subject on
google. There seems to be very little deliberate effort at parody and a
great deal of ******** on the web.

I've written a few articles about dry rot if you search on Google.
I agreed with the comments others already made that this doesn't
look like dry rot from what I can see in the pictures. However,
it's perfectly possible to have dry rot with no fruiting bodies,
and it's possible you can't see the mycellium, so it's impossible
to completely rule it out. The pictures aren't easy to examine in
detail. The location looks perfect for dry rot though.

The problem with something like this is the FUD factor - *if* dry rot can
consume your house, even after the initial water ingress is cured (by
supposedly generating its own water as a by product of eating the wood),
then you scare people into expensive work just to get a 10 year guarantee.

It needs a source of moisture (doesn't need to be visible water,
a damp wall will do). It will carry the water from one site to
another, in order to infect timber which wouldn't otherwise be
susceptable, hence its ability to infect dry timber, unlike wet
rot. If the water source is cut off, it will stop growing. There
could still be enough moisture leaking in from the house to stop
it from completely dying though.

OTOH, if that were true, given my roof has been dry for 10+ years, then it
should have continued to eat at least the entire rafter, not stopped after
about 8".

It's not true.

My concern is that once this ceiling is put back, there's no easy way to
monitor the situation, which amplifies the risk of getting it wrong.

Keeping water out, and ventilation are the important things.
Secondly, you can try protecting new timber against contact with
walls. Nowadays, joist hangers are often used which are much better
in this respect. The other technique is to wrap the joist ends which
are in close contact with walls (although the wrapping could be bad
if you end up with water streaming in, by keeping it in the timber).

But I'll go with the general opinion that the sodding mushrooms are

I couldn't make out any mushrooms in the pics. Were there some?

dead/inactive, and I'll just replace structurally deficient timber as is
practical, lob some fungicide in because it's cheap and why not, and
reconstruct things so that damp can never form there again.

You won't be able to get any fungicide nowadays which will protect
against anything, and there never was one which was particularly
effective against dry rot (it's one of the most resistant fungi).
The only protection was to make the whole area toxic with heavy
metals, but that's no longer allowed.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]