Found mould, help to find reason why

[BoneyEmm]

We've just bought a house, it is over 100yrs old. The structural survey was fine, didn't highlight damp issues.

Moved a wardrobe on the first floor to find this behind it.

We've took the floors and floorboards up and everything seems dry, the bricks we can see below seem dry. The plaster doesn't seem damp and is not damaged.

Any ideas what's happening here? It's about 1m from the window.

From halfway up the wall to the ceiling is fine too. Just the bottom half off the wall.

Just condensation behind the wardrobe. Air can’t get to it there, and I take it that’s a corner on an outside wall? Try not to put furniture on the corner of two outside walls, and make sure you ventilate properly and regularly.

Ah great, thank you. Yes it's an external wall.

Condensation, caused by a large furniture item disrupting air flow, esp on North facing walls.

Yes a north facing outside wall! Phew.

We've moved from a newish build so we're amateurs here ☺️. We were planning on taking up the floors anyway, we'd done the rest of the room already, so we didn't do that for the sake of the mould.

Should I maybe put some damp preventing paint on it when I've cleaned it to stop it coming back? As well as keeping it well ventilated

Damp preventing paint will be designed to stop damp coming from outside to inside. Unless you ventilate you will get condensation anyway, and mould could grow, on top of your paint. There’s no need for it, it will serve no purpose.

Thank you, one less job to do then.

Agree with pp on cause and no need for damp proof paint. Just want to recommend polycell 3 in 1 mould spray for removing it. The spray includes a mould preventative as well as killing what is there, so reduces chances of it growing back. I swear by this stuff when I found mould behind my DDs headboard (she’d pushed the bed completely against the wall without my knowing). Usually can find it at Homebase. Just make sure you have an open window and wear a mask when applying as it is strong.

If you can fit in behind furniture, we use these to absorb condensation in our old house in the winter months.

www.amazon.co.uk/ANSIO-Dehumidifier-Condensation-Moisture-Dehumidifiers/dp/B015AOGP1S/ref=asc_df_B015AOGP1S/?tag=googshopuk-21&linkCode=df0&hvadid=309920189752&hvpos=&hvnetw=g&hvrand=5694213928040306137&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9044871&hvtargid=pla-421104855774&psc=1&th=1&psc=1

Thank you, will definitely give the mould spray and dehumidifiers a try

Clean it off, dettol do a special spray for this which is very good, recommended to me by a lady who is a landlady, as provided you solve the problem causing it, the dettol spray will kill it off for good. Then ventilate.