There is a lot of information out there on roof washing, and some may find that other methods work best. We have compiled some information that beginners and new washers might find useful! Please test everything yourself before trying, we are not responsible for any damage resulting from these instructions.
First and Foremost
Roof cleaning CANNOT be achieved by using a down stream injector. You will need a dedicated pump of choice. Typically a 12 volt is a great place to start.
You need a much stronger application in order to clean a roof. You will need a large container, such as a 55 gallon barrel. You will make your mix, and whatever you make in that barrel, that is what will end up on the roof. Nothing is diluted like it would be with a down stream application.
Start with 30%SH / 70%WATER + plus surfactant. If that is not enough, work your way up to 50/50 + surfactant.
EXAMPLE: in a 10 gallon tank start with 3 gallons sh and 7 gallons water. If not strong enough, work your way up to 5 gallons sh and 5 gallons water. You’ll have to trial and error to see what works best for you.
Personal Advice from John Lange
Roof cleaning requires a little more skill set than house washing because the application is so hot, it us much easier to kill plants and things of that nature. Again, depending on climate, the ratio may vary.
Personally, I go very strong and always apply 50/50. We are also skilled, I am confident we will keep things wet and that nothing will go wrong. I would rather nuke the roof and save time rather than go weak and have to come back over with a stronger mix. That is just us though. Some pros out there will not go any hotter than 30/70.