What rot is this?

[nworb]

I've removed an old wooden lintel that was totally shot with rot. Above it was the wall plate, on slate and lime, in similar condition. Both were disintegrating into dark dust and had "strands" dangling. I hoped these were inedible wood strands and cobwebs but upon cleaning up the old mortar around the wall plate I've seen some scary roots and the underside of the floorboards show small blossomings of mould and red dust, as do the joists. It's not my flat but I am holding it up on acro's which is obstructing my flat and I can't do anything until the source of the rot is repaired (the upstairs bathroom), in 45 days or so.

Kindly advise on what I am seeing in the following photo's.

This is the joist under the wall where the water streams down.

This is the neighbouring joist, under the bath, displaying some magnolia promontories but passing the screwdriver test in these locations once 300mm back from the wall.

This is a root I found behind the removed wall plate:

Here is a better (but poorly lit) view of the rot and insect damage under the floorboards:

 

[TheVictorian]

To my untrained eye it looks like old dry rot, which isn't good news.

 

[nworb]

Old? The leak has been ongoing for the five years I've lived here. I have my floorboards up underneath and they seem fine. But then I'm used to a ceiling over them, so maybe it has been raging overhead all that time, but wouldn't the fruiting bodies be bigger?

The joists either side of these two are both solid, excepting the 20cm or so nearest to the solid outer wall.

Are these photos any clearer?

Untitled

• nworb
• 15 Oct 2012
• 1

Untitled

• nworb
• 15 Oct 2012
• 1