Just been helping my sister who's "new" 140-year old house has many, many unique fixer-up opportunities etc.
This particular problem is related to the floor joists in the kitchen, by the back door.
There was a piece of floor-grade chipboard, approximately 3ft by 2ft on by the back door entrance. This was "springy" to step on, and she suspected foul play underneath. Prising the chip-board up revealed the following two joists (apologies - bad mobile-phone images) :-
I've yet to get under the floor (I might need to lose a few pounds to fit under), but from what I can tell, the joist is good wood 2-3 foot in, and the problem would appear to be related to damp coming under the kitchen door over many, many years.
The joist is now dry - in fact there's a good amount of material that flakes off in your hand (sister stopped me before I removed all of the material with my thumb)
There is some evidence of creepy-crawly activity - there's obvious sign of wood worm at some stage, but the most obvious things are the occasional wood-louse (I saw 2).
My immediate thought was that, provided the joist timber is sound 2-3 foot in, I could get a, say 6ft length of similar timber, and bolt this alongside the joist (either 10mm coach bolts, or similar coach screws), sit this new timber on top of the same dwarf wall, with the end wrapped in damp-proof membrane. Maybe treat the original timber with some insecticide?
Is this sensible?, crazy?, is there any other suggestions from the people that know?
Any information gratefully received... then I can get back to DIYing on someone else's property :s
Regards
Mike