We've had possibly one of the wettest years this house has ever seen in its 130 history, and there is a lot of mould growing on inside walls in our house in places we've never seen it before. The very large patch growing out of DD2's bedroom just about takes the biscuit though. DH has been up to check there no leaky roof etc and can't seen anything structurally wrong.
I'm going to try to describe the patch but may have to put up a photo. It's rather like sticky slightly dilute black treacle, oozing out of and down the walls. Poor DD2 is starting to only half -joke -- that somebody's been walled up there and is now starting to ooze their way out.
We've tried washing it off, but it just comes back. Over the last weeks it's spread over a larger and larger surface. My feeling is that it's some form of mould caused by damp seeping through what is probably old lime and horse-hair plaster. Has anybody else experienced this? Does anyone have any solutions or suggestions? Any advice gratefully received!!
If it is tar, it will dissolve into brown in white spirit. If it is mould bleach will kill it and it will dry to powder.
I gather it is on a dormer cheek so probably caused by rain penetration. Get recommendations for a local roofer to look at it. If he talks about repairing with lead that would be a proper job. If he talks about sticky flashband ask him to leave.
It couldn't be mould caused by condenation as a result of draping wet washing around the house, could it?