I live in Portland, Oregon and it rains a lot here. I have a composite roof that is 17 years old and I want to treat it with something to remove moss. I have a power-washer and 20" extension wand and I'm wondering if I can use it to de-moss my roof without having to stand on it. I don't like walking on my roof and it's steep. Was thinking that I could either add some de-moss solution to the power-washer and use the wand to spray it over my roof. Or simply hook the extension wand up to water line and mix in some solution to de-moss the roof, but not sure it will have enough pressure to reach the top without the power washer and the right nozzle. Any other thoughts? Surprised someone has not designed a drone that can fly over a roof and drop de-mossing pellets all over it.

I have sloped plywood decking that I plan to float a tapered deck system on. I have gotten 2 contractors to look at it. One says do Hydrostop, one says TPO. Just looking for some consensus on one or the other. The roof would be difficult to access/repair once decking down so want to do it right as possible the first time. Any thoughts on which product to go with? Thanks.