Cleaned conservatory other day,roof was green so got it sparkling with rotary brush.went on to clean the pointy things on the roof with medium jet and to my horror the conservatory had leaves blowing all round it inside,told the custy it was a god joob i had brought the problem to light before warranty ran out ;)Leaves were dry and cleaned up no prob,never putting my lance near a roof again,sticking to drives for a while.