Damp external wall Damp can be a major issue in the home. Find answers to questions or post your own here.

[janec]

Hi have read the information but would be glad of any opinions.
My house is about 200years old, thick stone walls. Have ongoing problems with one small area of external wall in diningroom, damp patches and flaking paint mainly behind curtains. (Walls are paint on plaster)
This wall is very cold even when the heating is on, and the room opens into the kitchen on the opposite side of the room so is subject to some condensation from cooking.
Although I have been told by an expert I had in to look at it that the curtains have nothing to do with it is it likely that the condensation is worse behind the curtains because trapped there?
My plan is to replace curtains with blind, get a small dehumidifier ( any recommendations welcome) and redecorate!

Any comments welcome. also any suggestions about improving ventilation (sash window, painted shut.)


Thanks

[Perry525]

When you stop to think about it, you realize that windows rarely, if ever, steam up during the day. It usually happens at night, when the curtains are drawn and the temperature behind them drops, maybe 2 or more degrees.
At the moment with outside temperature below zero, I can just see a thin line of condensation forming along the bottom of my windows where the spacer is conducting the cold into the room. If I close the blinds, fine condensation will form over the bottom of the inner glass.
This is happening to your cold wall, probably every day and night to a degree, and noticeably so on cold nights.
The short term solution is to keep the indoor temperature steady, avoid temperature drops of more than 2 degrees and keep the humidity from the kitchen down by using a extractor fan.
A dehumidifier will help but, it will not solve the problem longtime in any event it will probably not be able to get the humidity down low enough to avoid condensation on cold days and nights.
The solution is to insulate the wall. If space is a problem? Use one of the modern closed cell insulation boards covered with a layer of plaster.