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I’m trying to figure out what is causing this area of damp, which is covered in these hard white deposits.

We’re in a mid-terrace Victorian property and this is the back wall of the kitchen. Beyond the kitchen is the bathroom, so it is not an exterior wall. I’ve been advised that the issue is rising damp, but is that possible if the other side of the wall is not outside? I also wouldn’t have thought rising damp would have the random patches like this does.

To me, it looks most typical of penetrating damp, but again, I’m not sure how this could be happening. Behind the wall is a shower, so I thought there might be a leak. However, from looking into the access panel behind the shower, there is no sign of a leak. The pipes do appear to be ‘sweating’ but there are no signs of damp in there - no musty smell and I cannot see any areas of damp.

Ventilation in the kitchen isn’t great and we are having that rectified shortly. However, this doesn’t seem to have the characteristics of condensation as some areas are slightly stained brown.

Any ideas?

Hi erb610
Looks very much like the damp course has failed or there is not one. If you have solid floors it could be that the DPM has not been taken up the wall.
Regards S

Would this still be the case on an interior wall?

Thanks Stoneyboy.

I was a bit confused about it being rising damp because of the patches. I thought it would rise up from the ground, but as you can see there are some random patches. Do you know why what could be?

Hi erb610
It is difficult to predict the porosity of not only the wall but also the coatings applied to it. You could hack off the plaster on the lower part of the wall and see if this determines the problem.
Regards S