How to stop condensation and streaming walls in cupboard

[nectarine]

In our bathroom wardrobe there is condensation streaming off the wall which goes to the outside. The bathroom has central heating but no ventilation, unless you open the windows which we do every day for a limited period. It is a stonebuilt house, but this wall has some padded kind of wallpaper which has been painted over but dark blotches are coming through, obviously the damp.

We've tried to correct the problem by drainage ditches around the house, which are drying out the house, but this condensation in the cupboard is a new one on us ... having said that, this is our first winter in this house so everything's new.

We have a dehumidifier going 24/7, but is there any other product (short of installing a n air vent) that could be used, or perhaps putting some kind of insulation (polystyrene sheets) against the wall to avoid the difference in temperature.

All advice most welcome.

[powerdesal]

As you obviously know, condensation is simply warm air condensing on the cold surface of the wall, therefore there are two choices:-

Increase the touch temperature of the wall or remove/reduce the amount of (or temperature of) the air touching the wall. Inevitably this comes down to ventilation and / or insulation

You really have answered your own question.

Even sealing the wall with some sort of 'painted on' coating is not really going to increase the temperature, in fact it could make it worse as there would be no moisture absorbed by the wall.

Are you sure it is, in fact, condensation and not penetrating damp.

Have you considered an extractor fan?

[nectarine]

Thanks, an extractor fan might be the last resort. I wouldn't know how to tell the difference between condensation and penetrating damp, but the wall is in good order as far as I can tell; however, the house is on the side of a hill and we have always had a problem with water coming into the sous-sol when it rained, so we have had deep drainage ditches cut around the house and no longer have that problem but I've now noticed this condensation and damp walls in the cupboard. Might the two be connected?

Apologies if this seems a daft question but it is really only in one area - the bathroom is well heated and the cupboard is only a few feet away from the radiator.

[powerdesal]

I am no expert, but I think your wall is now drying out and the problem may get less with time as the fabric of the building heats up and the trapped moisture is evaporated.

The fact that the bathroom is well heated and the cupboard is close to the heat source is exacerbating the situation.

Ventilation via an extractor fan would seem to be the answer pro tem unless of course a professional comes up with a better idea.

[Chancer]

Take the door off the cupboard for this winter.

Fit a VMC as soon as practically possible, you will not regret it.

I would not recommend a timer operated wall extractor fan unless it is physically impossible to fit the VMC.

[nectarine]

thanks, but what is a VMC ... is that an extractor?

[Alex H]

ventilation mécanique contrôlée - an inhouse extractor that runs 24x7

Explanation here (in french) http://www.ademe.fr/particuliers/fiches/ventilation/rub4.htm

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