Condensation mould?

[Almahart]

There is one room in my house with three external walls. It is well ventilated but there is black mould in there. I've been googling and it looks as if it could be from condensation. If that's correct what can I do about it?

Or could it be something else?

We've had similar and have just had to have our soffits & fascias and the gutters done. The roofers found that there was water ingress which had rotted the existing boards, and they said that was probably the cause of the mould on the ceiling inside.

Wipe it off with a black mould cleaner. Put a dehumidifier in the room. Check every morning if there is new condensation and wipe away. Check gutters outside and roof and damp course. Cut away vegetation so it gets more sun.

We have just bought a 1930s property with condensation issues. We are having an Envirovent system fitted in the loft which will reduce the condensation and stop mould from growing. My parents had something similar fitted in their old house and it sorted out the condensation issue within 24 hours of being fitted. We've been quoted around £1,600 which is well worth it for us (especially as we have 2 asthmatics in our family)

This is really helpful thanks. The mould is just above the skirting board so I don't think it can be guttering etc

Is it on the ground floor?

Post some pics please

Is the floor concrete?

Second floor. It's under a platform bed in a kids room that desperately needs re-painting so it looks fairly grotty

I had already wiped it off, sorry should have said that

When was your house built?

I get this on my living room along the external wall where a sofa and kallax unit is. Always worse in winter. I've just cleaned it all off with mould spray and painted on damp proof about 40cm above the skirting board. So far so good. I make sure the furniture isn't pushed right up against the wall aswell

It's a 1930s pebbledash housec

You could try taping some plastic/clingfilm/foil to the affected area and leaving it for a while, at least 24 hours. If there's moisture on the side facing the wall, it's probably an external issue but if it's on the room side it will be condensation.

Upstairs it’s most likely a solid wall then, even if there is a cavity downstairs. 100% it’s condensation, but do the test anyway. With 3 external walls, really the best option is to internally insulate them and be done with it.

I was wondering about internal insulation. Thanks

They're always 1930s houses when you read posts like this!
I have one and we get this. We do so much to keep on top of condensation, dehumidifier, open windows every morning with heating on for a bit, opening windows when showering and cooking, Google it there's loads of tips. It is better but not cured. Sometimes it happens and we've done everything, it's random.
Trying condensation paint now

That piece of wall will be cold and so it is attracting moisture. As for why its cold I dont know. Could be external brickwork could be the void inbetween 2 floors.

You say it is well ventilated. Condensation and mould often appear inside wardrobes, behind furniture and even wall hangings where there is not much air circulation.

Are there boxes or something under the bed?

Do you ever dry washing indoors?

I use Band Q bathroom paint - wipes clean and seems to slow the mould

Mould is usually due to condensation. Higher humidity levels make it more likely, and it occurs on the coldest areas of walls and ceilings, and/or where air flow is restricted by furniture etc. Furniture against the wall also creates a colder spot that doesn't receive as much heating. It's probably not feasible to move the bed away from the wall. Now that you seems to have cleaned it off pretty well, maybe the first step would be to redecorate this area with a mould resisting paint and see if it comes back. It's unlikely to be anything else by the way. Penetrating damp would have caused the paint to flake off or blister. And don't worry about rising damp. That would also have affected the paint and plaster, and in any case, salts from rising damp inhibit the growth of mould.

Also a good point by PigletJohn - was there anything under the bed pushed against the wall? That would need to be avoided.

Not where the mould is, but on the other wall (still external) there is wood panelling. I am wondering whether there could be mould behind the panelling. It seems a bit unlikely as there was only a very small patch on the wall where it was visible

I doubt there is mould behind the paneling, unless they put panelling over some mould without cleaning it off. But the panelling becomes the new surface which moist air will form condensate on, so any mould would occur on the panelling surface. The panelling probably makes mould less likely because its surface temperature is likely to be a little warmer that the wall.