Clean roof - what is the best/safest method? Steam clean or wire brush

Section62

TELLIT01 said:

If a contractor says they will walk on the roof do to the work my advice would be to tell them to 'do one'!

Or worse, they say they can do it all from ladders, then start walking on the roof half way through without telling you in advance.

Because this kind of roof 'cleaning' isn't really necessary it is a magnet for the kind of traders who don't think the normal rules and etiquette apply to them.