Horrified - lots of black mould hidden under the window frame

[Return2thebasic]

saw a bit mould started building up on the wall, so bent over to have a look... Gosh, I can say if it's good to see it or I regret seeing it (just so gross). Black mould covers the entire length of the underneath of the window frame. It's well hidden and probably have been growing for months.

We just newly painted the bedroom in summer. We've been leave a crack opening at the bottom of the window everyday. But I guess that still didn't allow enough fresh air draw out the humidity from under the frame.

I will try to clean it up. But how to prevent this happening at all? And the surface looks rather untidy underneath with some paint coming off and exposing the brick. Do I just clean it using spray as usual or some other way?

Pics attached.

Have you got a leak or is there moisture coming in the room somehow? Its strange its right under the sill.

You can use cillit bang mould remover, we use that in our utility room, it gets a bit humid in there as we dry the washing in there. Use it every so often or so.

@bellac11 Good point about leak. I will see if we can check maybe the window was not installed properly a few years ago and left any crack on frame?

But my first thought is the curtain which is heat insulating and reaches the floor. Maybe it allows the humidity get trapped overnight. The window doesn't have a vent, so unless we have it open, otherwise there's no air circulation from outside.

Is there mould around the rest of the frame though, as in behind where the curtain would be. I might expect any trapped humidity to be more widespread if that was the culprit. It only needs to be a small water ingress to make it damp I think.

But anyway its easy to clear away, just have to keep on top of it.

@bellac11 it doesn't seem to be anywhere else around the frame. Just the bottom.

Thinking back, before we replace the window, there was mould I'm that area too, but not as so much built up...

Is there any mould on the rest of that wall? Behind furniture maybe?

When its light, see if you can have a look outside with some binoculars (its upstairs I assume) to see if there are problems with the render or brick

Agree on the possibility of a leak, as it looks like it is in a pattern. If you wipe the edges of the window panes is there any mould? If so a lot of airing will help that. If it is just from moisture it will go with frequent wiping and airing. Keep doing it even after it has gone, as I made the mistake of stopping and it came back fast.

@bellac11 I will try to check outside. But just realised there's a rather big window box in the way 😅 Might have to find some muscles to move the heavy box first...

@Season0fTheWitch No, no mould in other area. But I just realised I probably need to turn up the heating in the bedroom a bit as an extra measure - don't like the dry air at night, so usually we just pile layers of duvets on top with radiator barely on.

@Pumpkin20222 No mould elsewhere around the window. And it's sash window... Really a pain to open and close, without air vent too...

I will clean it tomorrow when nobody is around. The cleaning agent is going to stink... And will keep it up from there.

Thanks!

Order some Ronseal 3 in 1 Mould Killer Spray. It will kill the mould and form a barrier against it forming again. We had a problem with mould on the bathroom ceiling, tried all the usual sprays but this Ronaeal one is for paintwork rather than tiles or shower trays, and worked best.

Check the curtains if they've been hanging over that area, they could be mouldy too

I've had to do a recent deep dive into this bc of DD accommodation -- what I read ( and I'm not an expert) said to be careful when cleaning it that the area is ventilated and your mouth and nose and covered.. also can help further by regular ventilation..
Google Luften - German's are obsessed by this to keep mould away and now I am too