Dry rot or not

[Crediblehippo]

What's wet and what's dry?
Remove the source of damp ingress - in every picture, it looks like the timbers are "soaking up" water from the brickwork. You want to wrap the ends in DPM wherever they're in contact with the brickwork. Looks like quite the undertaking, though. I think some of them might have been done already, can see a hint of some sheet material in there [not that it seems to have helped].

What's going on here with these newer timbers?
[GALLERY=media, 106195]Wood by Why Not Indeed posted 10 Mar 2021 at 10:02 PM[/GALLERY]

The white stuff looks painted on, rather than something that's grown. The ledger plate [?] looks to be damp on the underside, which means that it will eventually be completely damp.

I will check this and get back to you.

Do you think the timbers look beyond repair?

Can load bearing walls be honeycombed at subfloor level or is this a no no?

The area marked Din/room has been noted as being naturally damp by the contractors, and loose lay visqueen has been laid on the floor as a preventative measure to stop the condensation hitting the timbers above. Is this a viable strategy for the rest of the sub floor?

 

[Why Not Indeed]

Do you think the timbers look beyond repair?

No idea, sorry. That's what ^woody^ was getting at about pushing your finger in to it. If you can easily push your finger in to it then there's no strength there any more. Timber can get wet and then dry out, and be structurally sound. It's when it stays above a certain moisture content for a sustained period of time that it will rot.

Can load bearing walls be honeycombed at subfloor level or is this a no no?

Honeycomb sleeper walls are absolutely normal.

loose lay visqueen has been laid on the floor as a preventative measure to stop the condensation hitting the timbers above. Is this a viable strategy for the rest of the sub floor?

That's what I meant by "wrapping the ends in DPM". If that's already been done but it's still wet then either it hasn't been done effectively or it hasn't had long enough to dry out [the less airflow you have, the longer it will take].
When I said it's an "undertaking", I meant, how are you going to get it around the ends of the joists if they're still in situ?

 

[Crediblehippo]

Can you push your finger into it once its dry?

At the very ends yes they just crumble away but the white part is actually fairly dry. The white stuff just brushes off almost like chalk and the wood underneath is dark but fairly dry and I can’t push a screwdriver into it.

 

[Crediblehippo]

No idea, sorry. That's what ^woody^ was getting at about pushing your finger in to it. If you can easily push your finger in to it then there's no strength there any more. Timber can get wet and then dry out, and be structurally sound. It's when it stays above a certain moisture content for a sustained period of time that it will rot.




Honeycomb sleeper walls are absolutely normal.



That's what I meant by "wrapping the ends in DPM". If that's already been done but it's still wet then either it hasn't been done effectively or it hasn't had long enough to dry out [the less airflow you have, the longer it will take].
When I said it's an "undertaking", I meant, how are you going to get it around the ends of the joists if they're still in situ?

So I’ve been down there and the timbers are largely dry. The area which is my main concern the ends of the joists are dry but the wood breaks away with ease when poked at. The white patch of mould on the wood is dry and turns to chalk-like dust to touch, the wood beneath is darkened but dry. the wood with white paint on is dry to touch. I’m hoping that clearing the blocked air vent has implied things and hope to further improve air flow in honeycombing the walls.

 

[^woody^]

You need to let the timber dry for a few days or a couple of weeks and then see what it is like. If its sound you can treat it with preservative and then leave it.

If its soft, you'll need to cut out any soft timber, then treat what's left and then splice in or bolt on some replacement.

 

[Munroast]

I take it these walls are at ground level and are inherently damp?

It doesnt look like dry rot from what I can see, just a bit damp on the ends with may be a bit of wet rot. (It is dry rot you have to be concerned about and since you have had dry rot before then you need to be extra careful dormant spores can't spring back into life, be super careful with dry rot it can literally destroy your property, always get expert advice, and I doubt anyone can be certain from pictures.

I would expose the timber ends where they go into the wall so air can move round them, and may be put some damp proof material round them so dust and stour can't build up and create a damp bridge to them.

The timber wall plate that the joists are sitting on, I would be wanting to remove that and build up to the joists with brick, use a bit of damp proof membrane between the top of the bricks and the underneath of the joists.

After exposing all the ends leave it for a month or two then asses the condition of them, wet wood will just dry out ok, and wet rot just stops as soon as the moisture content falls.


I'm no expert just an enthusiastic amateur who owned an old property with all manner of damp and rot issues.

 

[Crediblehippo]

I take it these walls are at ground level and are inherently damp?

It doesnt look like dry rot from what I can see, just a bit damp on the ends with may be a bit of wet rot. (It is dry rot you have to be concerned about and since you have had dry rot before then you need to be extra careful dormant spores can't spring back into life, be super careful with dry rot it can literally destroy your property, always get expert advice, and I doubt anyone can be certain from pictures.

I would expose the timber ends where they go into the wall so air can move round them, and may be put some damp proof material round them so dust and stour can't build up and create a damp bridge to them.

The timber wall plate that the joists are sitting on, I would be wanting to remove that and build up to the joists with brick, use a bit of damp proof membrane between the top of the bricks and the underneath of the joists.

After exposing all the ends leave it for a month or two then asses the condition of them, wet wood will just dry out ok, and wet rot just stops as soon as the moisture content falls.


I'm no expert just an enthusiastic amateur who owned an old property with all manner of damp and rot issues.

thanks for this advice I will do so.

On the subject of dry rot, I have also found what I believe are small patches of mycelium growth coming through the party wall. This area has been treated professionally in the past but they would only give a limited liability guarantee for works done to the party wall, as they could not see what was on the other side. I know my neighbour has had some treatment done by a carpenter friend which involved replacing rotted timbers with DPM wrapped and treated timbers and spraying the area with fungicide. However, they don’t appear to have installed any new air bricks or unblocked the old ones, furthermore their gutters appear to be in dire need of repair.

The neighbour is in the middle of trying to sell the house so I’m not expecting them to invest any more money in the problem, I’m hoping to take that up with the new owner.

as the outbreak is localised only to masonry and in early stages I plan to treat myself. I have ordered some boron ultra 12 5% liquid, along with protective gear and a mist sprayer. I plan to remove the growths with a wire brush, bag up and remove from site. Then spray down the entire area and leave to dry for a few hours.

how does this sound? Any advice?