I’ve been reading the forum all morning trying to figure our problem out but thought it may be easier to post for advice from anyone who has more knowledge than us!
We live in a 1930’s detached house. We moved in in January and stripped all the walls in the living room back to brick, bricked up the old fire place and added an air brick and replastered and decorated. The walls are solid brick with no insulation. It’s worth noting that when it was back to brick, there were no signs of wet or damp anywhere.
Maybe about 2 months ago when the weather got cooler we noticed a damp looking patch in the corner of the room. It didn’t feel wet, just cold and doesn’t smell damp. We have a dehumidifier so put that facing the corner and it went away. However it does keep coming back, not too often but obviously would prefer to nip it in the bud whilst it’s not a big issue (hopefully).
We run the dehumidifier quite often and try to keep the house at around 55%. The heating is set to 19 degrees.
I’ve checked the other corner of the room and there is a tiny patch there too. Does this look like cold patches / condensation or something bigger? My fiancé is currently taking up the floorboards in the undecorated hall to crawl in to the floor space to check down there.
I’ve attached two photos. Any advice would be greatly appreciated! Thank you!