"Peter Scott" wrote in message ...
"jacob" wrote in message
om...
Having looked closer I can now answer my own question;
1 the severely rotten joists are old wet rot hence no cubic cracks
2 the rest is later (recent ) dry rot
3 I've found the telltale cubic cracks in a small area under the joist
at about the center i.e. oldest, part of the dry rot, as though it
started in one place and has spread out from there.
snip


Don't be too downhearted. Dry rot is not that difficult to eradicate. Cut
out the wood well beyond where it is infected and spray the rest. Make sure
that you burn the infected wood. Check that air bricks etc are not blocked.
Good airflow helps prevent a recurrence.

Peter Scott


Dry Rot, which it appears to be from your description in the original
post, almost invariably requires a source of moisture which is in
excess of hygroscopic moisture (ie places with high Relative
Humidity), in my experience they are always triggered by a specific
moisture source(s) such as plumbing leaks or penetrating moisture from
faulty rainwaiter sources etc etc.

The primary treatment for dry rot is the elimination of the said
source of moisture and, if this is done, no further treatment is
necessary - *providing* -that a further outbreak can not occur during
drying out. Retatining this situation is essential.

Also of course, as Peter says, cutting back infected timber is
necessary and, if you cut back 500mm past the 'frontier' you should be
ok. Remember to replace the timber with one which has been pressure or
vacuum treated with fungicide and treat all the cut ends thoroughly.

You can spray around liberally if you want, personally I would avoid
using chemicals if at all possible, but the golden rule is: control
the moisture and you kill the rot. This applies to all rots of
course, brown or white.

If you want a definitive test of your rot, remove one of the 'strands'
(these will be approximately 1/16 - 1/8 in diameter. Let it dry
thoroughly and, if it becomes brittle, then this is almost certainly
dry rot. As for mine fungus (fibroporia vaillantii)which is also a
'brown' rot and will establish cuboidal cracking), any strands will be
white, rather like string, and will stay supple even after drying. The
fruiting body is also white and looks like it has a 'honeycomb'
appearance. From your original post this doesn't seem to be the case.
(Also. your cellar would have to have been moderately warm for mine
fungus )to have flourished.

Cellar rot. or wet rot (coniophoria puteana)is also a 'brown' rot
which will produce cuboidal cracking but it can leave a surface 'skin'
which is devoid of these cracks. The damage will be visible beneath
though. It can also produce strands but these are much finer than dry
rot and remain supple when dried. Its fruiting body is usually quite
flat and has little nobbles on it. It may be that you have had both at
one time or another.

Rots are not to be feared, merely dried!

HTH

Xav