Wow its amazing how much Algae can grow on both your roof and render..
It can be one of those places that you may not be able to reach to clean but you just want it sorted..
Pressure washing is just not the answer, dont pressure wash your roof or render as you could cause a lot of expensive damage to your render or roof.
Soft washing is uses a 12 volt pump, pumping the soft wash solution were in needs to go to kill the root of the problem.
the soft low pressure way of cleaning roofs and render is a soft wash cleaning solution..