Marc i cleaned a con roof today with tesco own brand bio washing powder, very very good indeed.
I poured some into the top filter in a Gardiner's backpack, mixed with pure and sprayed all over the roof. Left it for 5 mins then scrubbed on a low flow before rinsing off with a high flow.
Is it better then screwfix, virasol, ubik etc...?
Yes!
Amazing results, it really 'eats' the dirt effectively.
Also you don't get bleeding from black seals like you nearly always do with the others.
This will be my go to now for fsg and con roofs. Screwfix will be good in a spray bottle as a quick spot on treatment for dirty windows.