I don’t rinse because:
a) most of the time the roof looks great without rinsing
b) if there’s moss or heavy buildup, rinsing isn’t going to remove it, only sun+rain+time will
c) it rains often enough in my area that any remaining brown is gone in a couple of days
d) the three reasons above make the extra time and effort unnecessary
On every roof I’ve done, I’ve offered the client both options. So far, every single one has chosen no-rinse. It’s cheaper for them and cuts down the possibility that fresh SH will go down past their downspout and out into the yard. Lots of homeowners don’t seem to know where their roof water actually ends up, whether it gets directed a French drain or into a flower bed.
My personal reasons:
There’s still a bit of effectiveness left in the roof mix for at least a few hours. I want to make sure that the moss and mildew is DEAD because I’m not a fan of washing things twice. Why rinse down chems that are still doing work?
I don’t like being on roofs to rinse, I feel like the pressure is still too high for the granules when I’m 6’ away from them. Rinsing from a ladder means there’s a good chance I’ll be shooting water up under the shingles themselves, and puts me at risk of knocking one loose or sending water down a nail-hole.
Rinsing won’t take down most of the moss I have dealt with. It needs to dry out in the sun after being killed, and takes time for it to decompose and fall off the roof. If you’re shooting off moss, you’re shooting off granules
I set the expectation of how long the process will take during the initial call from the client. At first they usually seem surprised, but then they Google it and realize it’s standard practice and that it’s safer for their roof than rinsing (for the reasons above)
Curious, how much extra do you have to pay for roof washing insurance rider?
Mine isn’t a separate rider so I’m not sure how the policy was affected to include it. But I’m good to wash/walk roofs for $1k/yr total
Mine isn’t separate either.
Rinsing down moss on a low pitch roof seems to take forever… Been rinsing one side of a small roof 3 hours… But if i don’t rinse it, apart from feeling like i’ve done half the job , i would be worried about grass and plants around the property? What about metal stuff that got sprayed? How long before roof mix becomes neutralized if not rinsed off?
I have been pre rinsing these roofs since I got out here but never post. The more roofs I do, the more I am realizing I’m trying to put earings on a pig. I am actually considering lowering my prices to justify less time trying to get the 20-40% of moss off without granule damage. Before me, handyman services scrubbed and pressure washed them. 100s of damaged roofs out here. Our moss is really heavy.
Roofs like that shouldn’t be brushed or rinsed where the moss is ripped off the shingle, the roots of the moss are deeply imbedded into the granules that turn into what you see as it gets worse and lifts shingles. When I get a roof like that I explain to the customer that it’s a roof chemical treatment and not a wash with instant results once i explain to them the difference and why it’s a treatment they’re ok with waiting for it to fall off. Once the chemical has done its thing and penetrated into the roots the moss roots will release and flake off over time with the rain and wind leaving the granules where they should be. It’s all about the sh doing it’s thing with roofs this bad.
I set the expectations at 2-6 months to fall off. The pre rinse is more of a debris removal. The redwoods just dump all over out here.
That’s plenty of time 
. Explaining the procedure is the key.
