I've recently noticed some spots appear on a pitched ceiling of our bedroom, and I'm trying to work out what could be causing them. I've only been in the house 12 months, and didn't notice anything last year, but it means I don't have a lot to compare to.
Here's some photos:
Altogether there are 7 of them, all at exactly the same height up the wall/ceiling. They range in size, the smallest being the size of my thumb to the largest with the photo of the ruler. The distances between them vary too (patches marked with an O):
O -- 65cm -- O -- 32cm -- O O -- 65cm -- O -- 25cm -- O -- 12cm -- O
I've had my neighbour (and ex-roofer) take a look, and from the outside on a ladder (not on the roof) he couldn't see anything that looked like it could be leaking from the perspective of the tiles. He said they looked in great condition. Additionally throughout heavy rain, this has been fine. It's only since we've hit freezing conditions that I've noticed it.
A small change from last year, is we also had our window replaced (sliding doors) to something less drafty. Could this potentially be a condensation thing? There are no vents etc on the outside of the roof - I've briefly read that vent tiles exist. The temperature of the room varies between 14-19 degrees C throughout the day/night.
Also worth noting that this is in the UK in-case that's relevant to the distances between. Appreciate any advice on what this could be/how I resolve it!



