Damp on walls

I have a room where the external wall is blackened by condensation. I have opened the windows for spells during the day but to no avail.
Would a humidifer work?
Any ideas?

You'll need to look at the entire ventilation in the house.Are there vents in the walls?
The room with the condensation will also need to be aired permanently - not just during the day.Most likely most of it coming from bathroom/shower etc or clothes on rads/cooking etc.

Yes there are vents. However the rad in the room does not heat too well. Only happens in this room.
Do you think a humidifer could help?

A humidifier won't do any harm but you'll still need to tackle the source of the damp.
I'm guessing it's an exterior wall as damp normally occcurs on the coldest surface (warm air onto cold surface) - is the wall insulated?

Are the walls with black mould north facing?Are the walls dry-lined?
A wall vent doesn't always provide the necessary air-flow - it depends on the direction they are facing.The problem could be warm air meeting a cold surface.Is there a window in the room.Does this suffer from condensation.
A dehumidifier could be a solution to draw the dempness from the air.Another solution would be to look at how the room could be better insulated - this is a more expensive solution but a permanent fix for the problem.

If you search in previous posts you will find some help, there are loads about damp/mould etc

The walls are north facing. There is a window and it suffers from condensation.

How long do you have the heat going in that room?

The heating is on in the morning and evening - however as the rads are not great in this room, it doesn't heat too much

keep the bathroom fan on draughtproof the bathroom door and keep it shut,the wet air from the bathroom after showering travels through the house and usually sticks to cooler outside walls,i had this problem and this sorted it out.

The problem is lack of heat. try fixing your heat and see what result you get.

gaggot said:

The problem is lack of heat. try fixing your heat and see what result you get.

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Must check my fridge in that case...

I had this problem with a noth facing external stone wall. Mould on a tiny section of wall. I cleaned it and put on a white type of paint that specifically prevents mould forming, got it in paint shop.As I have left tin in rented house I do nt know the name of it. I only put it up last week and I will have to give it a 2nd.coat. Do nt know if it will work.

I tried that paint aswell. Having terrible trouble with a section in our ensuite. Have a vent, open window during shower, have a fan but no rad...and I reckon the lack of heat is just the problem so going to get a rad put in later in the year. But back to the paint, it worked to a certain extent but still bits of mould coming back. Not as bad as it was but would rather get the underlying problem sorted rather than just covering it up.

I've posted elsewhere on this topic - but if you have a look at the following site, you'll find all the information you need to both diagnose and fix the problem. PM me if you need any more help...!

[broken link removed]

Good luck,

Pete

While quite a bit of what you say on your site is true, you have included a fair bit of BS. Dampness did exist before Portland Cement, Modern Paints and Gypsum Plasters. You should have gone the whole hog and said that dampness was due to 'slight wetness'. The reason that humans relinquished caves to the wild animals and moved to man-made buildings was because they were more comfy. The reason that people moved from stone houses with lime-based infil and lime plaster was because it was more cost effective and comfy. Heritage afficinados, granolas and just plain angry people rail against modern building methods. Ask any medical people, if 20th century housing has contributed to the nation's life expectancy, then sip your mead as you read the report.

To be fair to smallclough, he never said that site was his. And it certainly isn't. But it IS an excellent resource for understanding damp penetration in all its forms. And sceptics should educate themselves about the value of breathability and porosity before dismissing lime and limecrete as opposed to concrete, which is a far less sympathetic building material for old buildings that do not benefit from modern damp proof methodologies.

extopia said:

To be fair to smallclough, he never said that site was his. And it certainly isn't.

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He never said it wasn't his either and he refers to it a lot.

smallclough signs his posts as Pete and the company on the site is owned and managed by a guy called Peter. A strong coincidence.

Regardless, the site makes for knowledgeable reading.