Condensation on painted wall

[Grogs007]

I would like some advice re plastering a 17 th century internal chimney breast bedroom wall.
The house is empty , not lived in for few years so no heat. We noticed condensation/ wet on painted wall. Other walls in room dry. On removing plaster ( gypsum) is was noted that all plaster top and undercoat was dry. The question is do we remove all gypsum plaster and replace with lime. Or dry line or replace gypsum plaster. We are not sure why wall was wet ? Are we likely to get more issues than we stared with by replacing with lime? Something to do with dew point?
Any advice please.
Thank you.

 

[88v8]

Hello and welcome.

Assume the paint was plastic, ie unsuitable.

Is the fire flue open? Unused of course. If so it will be cold.

If the flue/fireplace has been sealed internally but no air vent and not capped it will be damp, which makes it even colder.

Ventilate the flue and put an elephant cap or similar on the chimney pot if any to keep the rain out.

Having rectified any such issues, replaster just the breast in lime and paint with clay paint or limewash.

Otherwise, tell us more....

You can drop pics in here via Photobucket or the like.