Just got in sorry misunderstood if its a conny roof just add to backpack did one a while ago the litchen was thick on roof completely covering panels that I gave a soak then scrubbed with stiff brush with backpack . owner was very happy and didn't have to worry about doing any damage to roof by not rinsing enough .If the roof is just green don't bother pretreating . If doing gutters ( I do them by hand as I like to get right into corners of brackets etc ) then I spray onto magic eraser / pad , muck comes off so easy its unbelievable .If you do gutters wfp then yes add it to backpack .
Even use it in backpack to clean windows 2ml per 100 litres and 2ml per gallon trad . Now noticing the sills are coming up bright when they are wiped down so its win win I am happy cos it does a good job for pennies and customer happy cos frames are whiter than normal .