Is this dry or wet rot... Or something else.?

[Snork]

Hi everyone. This is in my cellar and has appeared within the last few months. I noticed it last week. It's a 1920s semi in Derbyshire. Wall to left is North facing, wall to right is East. There are no signs of it elsewhere, just here, nothing visible at all outside the boundary of the photo. The joists are directly above the top edge of the photo. The bottom of the joists are maybe an inch or two above the soil outside. So the top brick in the photo is mostly, possibly fully above ground. All the wood of the joists and floorboards seem fine and the strands are heading downwards not upwards towards them. Outside approx 10 inches away from the wall but on neighbours side of the fence right next to the fence there is a discarded plank of wood about a foot and a half long on the soil, it looks like it's been there at least a year maybe 2, there's two more discarded pieces about the same size within 3 meters of the house also just on their side of fence. I am of course insisting that the neighbour moves them immediately. There are no leaking gutters, we have both had new roofs in the last 18 months and there are no drains nearby. Wall on the right is the party wall, I've been into the neighbours cellar and there is no sign of anything untoward. I bought some everbuild dry rot stuff for masonry but now I'm doubting myself incase it's not dry rot. I have two windows in the cellar which are opened periodically in winter, left partially open most of the summer with a rodent proof mesh and I have two dehumidifiers on a lot of the time down there as had a slow drain leak rectified a couple of years ago. The aforementioned drain leak, windows and dehumidifiers are over the West Side - opposide side of the house to this photo. Watertable is below the foundations on this side of the house as there's a small patio and then the land falls away quite sharply. Land at front (South) and West of house is flat. and I'd say my cellar is about as dry as a cellar gets currently but this small area admittedly does look a bit iffy.
Thanks for reading. What is this and what should I do about it? Thankyou.

 

[Snork]

 

[Tuffa]

Hi,

You’ve given a lengthy description, but it would have been great to see a photo including the joists, and of the external area on the other side of the wall! My googling leads me to believe it is wet rot.

You say the joists appear fine. I assume you’ve tried jamming a screwdriver in various places and have met solid resistance. However, I wonder how much of the joists ends you are able to see/prod. In the absence of a photo, I wonder whether the ends are embedded in the wall and not visible? In which case I would remove the brickwork to one side of the nearest one to see what state it is in. Also, I wonder whether the joists are resting on a timber wall plate, which (according to your description) could be at (or immediately above) ground level? I don’t know enough about 1920s construction to know whether such a wall plate would be bricked in (and so not immediately visible). This could be hidden source of the rot?

You’ve covered off a lot of possible causes of moisture. In the absence of photo’s I wonder if the external ground slopes towards this wall, rather than away? Your gutters may not leak but are they currently full of leaves, or is downpipe blocked? If you haven't already (but I suspect you have!) then get outside with a brolly in the next downpour in order to be totally sure everything is in order there...

Reading between the lines I am guessing there is no *permanent* ventilation in the cellar, e.g. air bricks? I would be surprised that the house does not or did not at one point, have this. I would be tempted to install an air brick at front and rear to allow passage of air. I think this would remove the need for dehumidifiers. I live in a ~1640 house with original ground floor joists; the whole floor sits above a cellar; there is an air brick at the front and one at the rear....

Good luck!

 

[Snork]

Firstly thankyou very much for your response. I really do appreciate it. I didn't include pictures of joists as visual inspection, texture colour and hardness of all wood is excellent. They aren't on a wooden wall plate, I can jam my screwdriver down the sides of them where the 'sit' though not from both sides, they are sound. I used to work with wood am confident they are good. The soil outside near this area is level for about 4 meters and then has a 5 foot steepish drop away from the house. We have a v small concrete floored conservatory taking up some of this 4 meters. It has two air bricks in the base of it into the cellar. There are two more airbrick on the front if the house. None on the side but does have windows that are pretty big maybe 75 x 75cm on the side. They are the other side of the house. I open then wide fairly regularly but as they are mostly below ground in a recess there is very little breeze. Once I know there's no spores I'm going to put a fan down there to help move the air around. Our side of the fence is tidy and just soil, next doors is a mess of discarded wood and plastic as well as leaves. I'm going round tomorrow to empty it. I'm planning to dig a hole next to the house (ours and neighbours, fill it with gravel and then pour copious amounts of the dry rot treatment over the surrounding area between our conservatories and then block it off to wildlife. I will also clean their gutter, there is a plant in there's so will remove that as yes thinking about it although not damaged it could be causing an issue. Ours is fine. Then I'll go inside, spray this fungus and the wood and wall 1m around it with the rot stuff I've got. Scrape it onto a plastic sheet below. Respray and wire brush it, wipe it and respray. Then remove plastic sheet and contents and pour the treatment on the soil below the area too. Do you think this is enough or should I be drilling holes in the walls and squirting treatment in too? I've left the dehumidifiers on before I saw this (they are off now as don't want to waft spores) as they moved air around a bit and do seem to be getting a fair of of water out if the air. One thing I forgot to mention is I often have a little electric radiator on down there too but it's not near this corner. I think we'll add another airbrick in this corner tbh too.
I was starting to lean towards wet rot too as there's no grey or white cotton wool looking stuff anywhere, luckily my treatment stuff should cover wet rot too by the looks of it. I was so sure it was dry rot initially though that then I didn't trust myself.

 

[Matt Green]

It's Cellar Rot, Coniophora puteana.


M.

 

[Snork]

Thanks very much Matt. Just looked at my treatment stuff and it covers that so we are going to get started rectifying it today.