ive ask to clean a consertvatory roof , there no problem in cleaning roof its getting access to roof , problem is there is a slate roof i have to negioate . the roof is about ten foot of the ground and about ten foot in span with no ridge on to attach a roof ladder , has any roofing got any ideas how i can attach a roof ladder so that i dont crack any tiles and dont slip of the roof , the roof is not that steep ,but roof has green slime on and customer does not what tiles broken