Mold in one bedroom

It's a lack of air circulation that causes it. We had it in one bedroom that isn't used unless we have visitors. Putting the de-humidifier on after the mould appeared did nothing. I got some anti mould spray from the Brico (make sure you use a mask and gloves) and then washed it down afterwards. Then repainted with anti-bacterial paint (you can get loads of different colours from the Brico) and thereafter ensure doors are left open, including wardrobe ones, when you go away for a while. Other times open doors and windows as often as you can to stop it coming back. You can also get anti humidity crystals which you just leave in the room and you'd be amazed at how much water they suck up. Not very expensive but salt (cheaper than chips here) will do the same thing. 

We did ours about 6 years ago and it hasn't come back since.

You could consider installing an air vent. 

Just reading your reply ..  you say about humidity crystals, then say salt will do the same thing. What sort of salt? Just the normal stuff you buy in a bag at the supermarket? I also wondered whether rice would work. We have a built in wardrobe without vents, which would benefit from this, rather than leaving the doors open. Cheers

Anything that soaks up water will work but rice is a euro a bag and salt about 12 cents. 

Ah, right. Good call !!! I’ll definitely be giving that a try next week. Cheers

Hi,

   we had similar problems and did what Grannyrose has advised, installed air vents. We put one in every room plus the upstairs landing. This has solved the problem for us. The builder charged 50euro's per vent, drilled them through the walls with a large circular diamond tipped drill and it took approx. one hour per vent.

  I fitted closable covers to all the vents so that we can close when it is too cold, these I purchased from Leroy Merlin. Obviously they have to be mostly open or it defeats the purpose of having the air vents.

 If the mould had persisted after the vents had been installed our next step would have been to insulate the outside walls affected. 

  The above assumes you have no external issues with your walls that are letting moisture enter, i.e. cracks in the external render, gaps around window frames, etc.

Rgds,

Aitch.

From what you've described, it sounds like there could be some underlying moisture issue, especially with the recent change in occupancy. I haven't personally experienced this exact situation, but I've heard that mold can be quite common in humid climates or when there's poor ventilation. It's great that you're being proactive about finding the right solution. I recently came across https://www.alldryus.com/texas/houston-mold-remediation/, and they were really helpful when I had a mold problem in my home. They might be able to provide some insight into your situation.