Black mould where ceiling meets wall

[DarkDarkNight]

I’ve just had coving and skirting board removed today in preparation for plastering and there is some mould where the wall meets the ceiling. It’s concentrated in a corner but there’s a little more along the wall. I’m not sure if it’s from damp or condensation. I have some time before the plasterer is starting so would like a plan of what to do.

I can clean with bleach or black mould remover for now but do I need a builder or roofer to check?

I was planning to get all the guttering checked as the survey said about a broken gulley where the downspout discharges at the front but there are birds nesting in the guttering at the back so I was planning to wait.

It’s very likely lack of ventilation. Maybe because if the coving, room itself or anything.

It could be a cold bridge because if missing insulation or leaking roof but both these are very unlikely given.

Clean it up with mould remover. Leave trickle vents open and see if the problem returns.

We had a lot of moisture in a bedroom corner like that, which I'm sure would have gone mouldy eventually. We were concerned about a roof leak. Luckily before we contacted roofers, we realised our son's gaming computer was underneath and the heat from it was causing moisture to rise and condense in that corner.

Better ventilation (and fewer old glasses of water left in the room etc) fixed the issue.

Is this a bedroom or bathroom? We had this and soent lots of money on checking the roof gutters fascia boards etc. the answer was lack of ventilation and moisture from us / our lifestyle.
we solved the problem by opening the windows regularly, and using a small dehumidifier overnight in the bedroom

do you hang washing to dry in the house, have adequate extractor fans etc??

Use mould killer rather than remover. The latter just bleachs it.

Hello, thank you for the replies. This is on the hallway above the stairs. It could very well be lack of ventilation, there is a vent in the bathroom into the loft which I haven’t seen before, but no proper vent through an exterior wall. When the bathroom gets done one will be added.

I am very hit and miss when it comes to opening windows so will try to do it more, especially after showers.

The odd bit of clothing gets hung on an air er near the radiator so I will look in to a small dehumidifier.