What kind of damp is this? How can I keep it under control for 1-2 years?

[questionsquestions1]

When we bought our house there was an internal wall with evidence of damp. It appeared to be old damage, with no current damp problem. We left it as that part of the house is due to be extended at some point, so that wall will eventually be removed.

However, it's recently started to get worse. the picture shows that the damp is only on an internal wall that joins to an external wall. There is no damp visible on the external wall. (click on the picture to see a larger version)

It seems to slope down from the external wall, suggesting it could come from outside. However it also looks like it could be rising damp. I'm not sure.

As that wall will be gone when we extend in a couple of years, I'd like to keep it under control, avoid breathing in mould, but also avoid expensive treatments!

Two questions:

1. Does anyone have a view on where the damp is most likely to be coming from? e.g. does this shape suggest rising damp, or damp coming in from outside?

2. I realise all the official advise is always that you must treat the root problem, BUT given the wall will be gone in a couple of years, is there anything I can do to seal the problem in for now and keep mould at bay?

Thanks

Ask @PigletJohn he’s always really good at this stuff

Rising damp is a myth, you have water ingress somewhere from a leak, failed pointing etc. Is the corner of that wall external facing? DPCs are an unnecessary waste of money. Not to say your problem wouldn't be expensive to fix but a DPC will more than likely not fix it.

What rooms are next to it, where do your pipes run?

There’s no such thing as rising damp. You should try and understand the cause and repair as it could rot woodwork or joists. It’s usually a window/roof issue, maybe guttering, ground levels or flashing somewhere. We’d need to know more before hazarding a guess.

it seems to be centred on the corner of two external walls.

What is on the other side of those walls?

stand back and take a wide picture that includes the brickwork, the drains, the downpipe, the gutter and the roof above, and the airbricks in the wall, and the chimney.

Is it a concrete floor?

oh, and please draw a floorplan, showing the damp patch in relation to such sources of water as the external stopcock, the drain gullies, the kitchen sink, the bathroom, and radiators on the walls.

The floor is concrete (I think)

Here are some external images. It will only let me attach 3 images, so I'll put a diagram in another message.

Here's a rough layout

I'd be checking out that sink first. Where are the pipes supplying it?

ha!

www.mumsnet.com/uploads/talk/202107/large-885420-damp-2.png

i see no reason to doubt that you have the typical broken and leaking drain.

observe the concrete that has been patched at the foot of the pipe. This is done when a long-term leak washes away the soil beneath and the concrete cracks and sinks into the hole.

your wet patch is clearly adjacent to the pipes

ask around local friends and neighbours for a reputable local small builder. Do not use an advertising website masquerading as a recommendations website.

Most likely the concrete will have to be broken up to expose the fault, and, after repair, it looks to me like the surface should be dug out and new concrete laid at a lower level. You see where there are more pipes disappearing into the concrete with no gulley? It has probably been laid raising the ground level above the dpc.

this is all very common.

it is quite a pleasant summer building job in sunny weather.

Walk round the house looking for the dpc. I am pretty sure you have one, it is probably a line of slate in a mortar bed 9 inches above where ground level used to be when the house was built. you may be able to see it beside or under the front door. Mark it with chalk and run the chalk line at the same level all round the house, especially where the dpc has been hidden by render or concrete. Slate lasts at least 400 milion years so it will not have worn out.

If, as expected, you have a concrete floor, the water is soaking into it and, if the dpc is bridged, passing into the bricks.

I'm also pleased to see that you have a fern. A fern will grow wherever there is a contuous supply of water keeping the ground moist. often an indicator of a leaking pipe or drain.

have you ever seen wild tomato plants, or red worms when digging the garden?

and moss too!

look out during and after rain, and after an accomplice pulls out the bathplug, to see if water is dripping or leaking from a fault above the ground.

You are always so fantastically helpful to everyone @PigletJohn !!

Thanks @PigletJohn. The picture may be misleading - the part that looks like newer concrete, is just cleaner. I was pressure washing earlier in the summer, but haven't finish the job!

I can't see a dpc anywhere.

We're going to extend in 1-2 years, so I'm hoping to avoid breaking up the ground, and having things repaired now. It should be cheaper when we're having the damp wall removed and the ground outside dug into for foundations anyway. Is there anything I can do to minimise the impact of the damp in the meantime? And ideally seal it in so we don't breath in mould in the house?

digging up and renewing a broken drain is not a big job.

otherwise I suppose you could stop using the bathroom and stop water goung into the broken drain for a year or two.

Honestly as piglet John says you really are better to work it out now- there could be issues underground the cement which you need to take into account to do the work. And in 2 years that’s going to get much much worse and smell grim, unless you stop using all equipment which sends water down that pipe.

Your poo is leaking into an internal wall in your house! I am all for a quick patch when you can get away with it but I don't think this is one of those times.