Condensation or Rising Damp?

6 Mar 2023
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United Kingdom
Hi all,

I wonder if anyone could help. I've recently moved into my property and noticed damp patches on certain walls. They are less than 1 meter from the floor like rising damp would do however there is no real tide mark. When the heating is on and cooking etc the walls in question can get wet to touch and you can see a wet tide looking mark when its wet. The main wall in question is a exterior facing wall (no cavity) and the lower part is colder to the touch than other area. This wall is covered from the elements due to being protected by an alleyway. I've tested the walls with my meter and the levels are very high including a partition wall between 2 rooms and an adjoining wall to the neighbours (not as bad as exterior facing wall).

I've had a couple of damp proofers say it's rising damp using the same damp meters I've used but I'm not so sure as I've heard so many stories. There doesn't seem to be much air circulation as a vent does seem to be have been covered and the fireplace blocked off. When leaving windows open or dehumidifer on it does help with the wet walls. There is no sign of mould and the windows of the property have no sign of condensation

Can anyone advise?

Last edited:
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How high is the exterior ground level? may be breaching dpc, though you mention a closed fireplace so if this has not been capped and vented could be the cause of all the damp.If you have a covered alley this will further restrict air movement and increase dampness in walls. Any sealed vents with also exasperate the damp problems.Damp proofers will always find damp [they are unemployed without it) the fact they mention rising damp is a sign of ineptitude.
Hi, Thank you for the reply. The exterior is not above the floor level. There are signs of a previous dpc (holes alongside the exterior wall) which are not capped off. =

Attached image of exterior facing wall.
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More pictures attached. The vent outside I'm not sure is for the old fireplace


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View attachment 297586
Attached image of exterior facing wall.
The wall with the fireplace appears to have a long damp patch coming from floor level, shaped like a range of hills. This will not be condensation, it is soaking up from the floor. IMO very likely a plumbing leak. The source is probably near the highest point of the patch.

Stand back and take a wide pic of that entire wall from outside, including the ground and the gutters. His old is the house? Can you see an original slate DPC at any point?

Is it a concrete floor, and is the floor wet?

Draw a plan of the building please, inducating the wet(test) patches, the position of the internal and external stopcocks, the waste pipes, drains and manhole covers, and the routes that buried pipes are likely to follow.

Under no account allow anyone who sells silicon injections or damp-concealing plaster into your home.
Looks like pink gypsum plaster Vs lime plaster on wall.
Maybe it should be lime plaster with breathable paint over would work better?

Cork plaster for insulation on walls is something I'm looking at for interest.
Think this could be the answer for some
Plaster will not repair a building defect such as a leak.
Latest fix radio podcast covers damp and condescension in homes with possible fixes. Well worth a listen. Getting more common with aged properties, solid walls with no ventilation.
People are making homes air tight while creating lots of moisture that's dumping on cold surfaces. Especially with modern heating.

Also reading up on damp meters they don't work. Complete scam. Might as well hold a babies pram against a wall.

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