Mould

[boomsi]

One of the bedrooms in my house has got a bit of mould and I noticed recently that when it rains, it looks like drips are coming through to the ceiling.

We've had a look up the attic and it's completely dry so it's not the roof. The 'drip' marks (have added photos) wipe off straight away, making me think that it might be mould as well?

There is also moisture all around the window. What might be causing this and how can I fix it??

The rest of the rooms upstairs have a little bit of mould but nothing major, it's mainly this one room.

Help.

Have you checked guttering and drain pipes outside? Failed pointing and a growing weed was the source of a damp patch in my wall once. Is the window frame sound? Is it coming away from the wall anywhere?

We've just discovered damp and mould growing in a built in wardrobe, due to failed flashing between carport and wall, allowing water to pour straight onto the brickwork. Once we fixed that the mould stopped growing.

Like previous poster- I wild definately check any gutters. Need to check they are not full of debris, also need to check any joins are not leaking. Also check for any gaps in any pointing between the bricks.
If you have been in the roof you do need to get right to the edges and check under any edges of insulation along the beams above where it is dripping. If there is a lead flashing gully- need to check that that this has not failed with a tear, or if any adjacent pointing of the roof tiles has not failed.
look for any slipped or broken tiles above that area.
It could be a case of condensation if this is the coldest corner of the house, especially if the radiator has been turned down in the room if not used much ( my corner bedroom window is is north-west facing and gets most of the window condensation). Trying to lower the internal condensate is worth considering ( using extractor fans in the kitchen, keeping the house at an even temperature, regularly opening windows to exchange the air, if you dry clothes indoor consider getting a dehumidifier etc)

Ours is on the run since we got a dehumidifier

Just because you can't see anything in the attic doesn't mean it's not the roof

Thanks so much for the suggestions!