Mould in our bedrooms around the edge of the ceiling and top of the wall?

[PlinkPlonkFizz]

We have triple glazing and a 1950s house, it's poorly insulated upstairs.

I've noticed the beginning of black mould growing at the tops of the bedroom walls and at the edge of the ceiling.

We run a dehumidifier every few weeks but is this not enough heat, an issue with the attic, an issue with the walls or something else?

Houses need to have a flow of air. Every time you breath, shower, cook it’s going to up the humidity.

I have some windows open all the time, I used to have one in every single room but shut downstairs ones in the late afternoon.

I'd definitely try and keep windows open a bit and run the dehumidifier more frequently. You need heat and air flow to prevent mould.

I have just wiped mould spots from around the top of walls in my bedroom too. Apparently, we breathe out up to a pint of water a night!!!! Common problem at the moment.

You could try clearing your gutters and see if this makes a difference.

Thanks @Jijithecat good point, I don't think we have done that in a while.

@WonderfulCounsellors @cezannesapple @Comeback25 probably haven't aired the rooms as much as normal, I'll do that then run the dehumidifier a bit more too.

As pp states check gutters and also loft above those rooms for a leak.

You can wash down with mould spray or bleach solution. I then spray stain block once dry.

Good ventilation. Clear condensation from windows. Encourage air flow.

How does this help?

We had this, black mould along the coving upstairs. We had the hip of the roof repointed and some insulation added in the loft and touch wood it hasnt got any worse this year. It cost £350. We still have a small patch in the other bedroom which I think was due to poor ventilation as we have kept the windows open all day and it seems to have helped.

We had the exact same thing last week. House same age too.

I’ve cleaned it all off (bicarbonate spray) and will open windows more. Also going to get guttering checked out. We’ve been here years and it’s only just appeared.

Blocked gutter when this happened to us.
I would check loft/attic space for any leaks and damp. Look at the outside wall (assuming this is an outside wall) in daylight to see if there is any damp patches that correspond.
Use mould spray and condensation paint (this removes, but doesn't resolve the problem).
Ensure windows open 15 mins a day at least and heating on (not at same time) enough to warm the house.
Dehumidifier at night if necessary

It can sometimes be caused by the loft insulation not being fitted right to the edges of the loft, leading to cold air pockets I believe.

We had this - it was porous concrete gutters causing the problem.

We had the gutters removed, capped and modern plastic external ones put on. The problem has completely resolved.

We have this and have tried it all including clearing gutters. Have finally discovered the cause (we think), as a pp mentioned not insulated properly in the attic right above where the mould appears. So we are putting insulation in to those parts and hopefully this fixes it.