Do I need to get this treated?

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Hi, I have just moved into a 1930's solid wall house and having removed the wallpaper there are wave marks on the plaster about 6 inches above the skirting. This is on an internal wall in the hallway and living room and next to the front door. There is no damp smell, it's not wet and the wallpaper was fixed firmly to the wall and the waves not noticeable when the paper was on. Having a look outside there appears to be newer patches of render above the dpc so I'm wondering if the damp problem has been fixed in the past, and if so can I just paper over the plaster. The paper looks to be around 20 years old so I'm guessing the damp and repairs were around that time.


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New Member
The black 'mould' at low level is symptomatic of condensation - taking moisture readings from the skirting would tell you a lot.

Additional to a 1930's build having some sort of DPC, it's likely to have a 'cavity' (relevant to external walls only!), albeit probably a very small one, could be debris in the cavity bridging, facilitating laterally penetrating dampness - a common problem in areas with weak/crap mortar.

Also quite common (and still today), DPC's were omitted from internal walls, so external could be dry, while internal have damp problems.