Stains on Roof Tiles

Hercules1946

Hello - Im new to the forum
I have some dark grey material thats clinging to my roof tiles and its spread on to the outside PVC Window frames and Sills of my dormer, which is very unsightly as they are white. It clings quite firmly but it can be scraped off. I was hoping I could find a suitable cleaner but Im not sure whether its mould, algae, lichen etc. Can anyone advise me?
Ive taken pictures, but Im not sure if Im allowed to post them.

Hercules1946

My first post, and I've got you all stumped eh? :rotfl:
Never mind... I'll just have to get on with removing it, and see if it starts to re-appear !

Thanks to the ninety odd that read my post.

MX5huggy

Put a photo up, but I would expect it to come off with a pressure washer.

nickj_2

it could be lichen , does it look like this , if it's on the roof it won't do any harm , on your windows it will come off if you give it light rub witha bit of warm water and a nylon scourer , do a small test patch first