Slate roofs yes, but those modern tiles can be tricky. Not just tricky,
but absolute little bumbags when it comes time to get the old briggs and stratton out.
What I didn't know is that the newer tiles (anything other than slate) have a special weatherproof coating sprayed onto them before they leave
the factory which (weatherproof it may be) doesn't stand up to the punch of a jet washer. Yes my amico's you can pressure wash it straight
off and if you do, your up for a repair bill that'll make you want to kill and eat something. And if you own one of those inflatable chairs, you WILL find yourself sailing around your livingroom come the first downpour that crosses your way.
Eventually I phoned a company based close by in Stirling (thanks and free plug to
as bad as it shouldve been.
So beware, if you have a dirty roof, never pressure wash it you'll so more harm than good. Instead, if you don't want to pay someone to do it, get a gallon of TFR (traffic film remover- I know this now), apply liberally and rinse of with a light (LIGHT) pressure spray after about 10 to 20 mins.
Its come up as new and you'll save yourself the trouble, as well as the
repair bill, of having to get the professionals in.