[M Roberts]

This looks good for slate roofs https://www.youtube.com/watch?v=vURkwIqHSK4

In other posts you don't agree with pressure washing roofs ?

Lee's video is fine, but I wouldn't touch slate, if you discover any are not pinned or broken, who carries out repairs as it would require total strip and re-peg, sure he covered this with custy but still a risk

[Smurf]

This looks good for slate roofs https://www.youtube.com/watch?v=vURkwIqHSK4

In other posts you don't agree with pressure washing roofs ?

Lee's video is fine, but I wouldn't touch slate, if you discover any are not pinned or broken, who carries out repairs as it would require total strip and re-peg, sure he covered this with custy but still a risk

Low pressure steam would be fine but like you say depends on the state of the roof.

[Plankton]

http://www.softwashing.uk/