Parents roof clean.

[Herm]

I'll attach a pic of my parents roof that they want to clean, well that mean ls me clean anyway, they are in Cornwall so I'll have to take a day off to sort it.

How's best to approach this? They live very high up by the sea and the less time I'm up on something the better!
Would people suggest a scrape and but some hypo or bio on it and leave?

 

[Pjj]

Looks like natural slate ?. I would scrape first and then a good hypo mix its not that bad , ware about in Cornwall ?

 

[Herm]

Looks like natural slate ?. I would scrape first and then a good hypo mix its not that bad , ware about in Cornwall ?

I'm not entirely sure if it's natural, but now you mention it I think it might be. They are in Looe mate.