Roof wash runoff

I am good about reducing runoff and bagging gutters during a roof wash. Once the roof mix has done its job and has dried, will future runoff from the rain affect the grass and plants downstream of the downspouts? The byproduct of a roof wash is sodium, right? Seems that is it doesnt get diluted enough because of a light short rain there could be a lot of salt coming off the roof. What do you guys do?

I had a customer ask the same question, will wait to hear what others have to say.

I use a little gypsum pellets for peach of mind

The solution is inert in about 24 hours, and the salt produced has never been enough to cause issues (unless dried directly on plant foliage), IMO. The issue comes in if you have a light rain within that 24 hours. The solution being dried doesn’t mean the SH isn’t still actiuve, and a little water that runs it down within 24 hours will have the same results as spraying/spilling SH directly in the downspout areas.

For that, there’s a few options.

  1. Don’t wash a roof if there is any rain forecast within 24 hours
  2. Rinse the roof thoroughly yourself, to make sure runoff is sufficiently diluted.
  3. Some sort of neutralizer system (NeutraPods are one we have tried that seems to work)

Some sort of plant wash or gypsum pellets has always been said to help also, we’ve done both in the past as well. Neither of these do much directly for the solution washing down off the roof though.

Thank you for your direct and on topic reply.

If it’s a light rain, not that much going to runoff anyway if house has gutters. The ideal situation this time of year is you wash roof in morning, get good thundershower in the afternoon. On a hot roof in summer, SH going to be non-existent in a few hours and it doesn’t take a lot of rain to to dilute mix.
Where everyone use to get in trouble was mainly in FL on roofs w/o gutters and they didn’t rinse bottom 3-4’ of roof. That night, with a heavy dew, that would cause enough runoff that by the next day you had a dead strip below drip line.

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