Roof Wash No Gutters

I washed a house yesterday with vinyl siding. It came out really nice. The owner wants the roof washed as well but the roof on the covered front porch has no gutters and the drip line is right over planting beds. While washing the siding above this area, the house wash mix did run down the porch roof and drip onto the vegetation in the planting beds. I rinsed the plants before during and after & also applied some gypsum pellets.
I am concerned that if I apply a stronger mix directly to the roof that as it drips off the roof it will harm the plants. I use a booster pump to apply my wash mix & I do not think I can control the volume enough to keep the solution form running off the roof.

  1. If I rinse the vegetation and have gypsum pellets spread, am I still at risk of killing plants?
  2. Would it be better if I used a pump sprayer on this roof area to control run-off better (fairly small area) & if so can I get enough solution down to kill the lichens on the roof?
  3. Has anyone used the granular SH neutralizer & fertilizer? Does it work well enough to safeguard against a hot roof mix?
  4. If I push this job to a warm winter day, would that be better? (I am in Indiana).
    Any advice is appreciated!
    Dan - Brighten Exterior Cleaning
1 Like

I dont do roofs yet but this is what I’d do.

  • Water the crap out of the plants

  • Get some heavy mil plastic from lowes or home depot and cover them with that.

  • Do that section of the roof first

  • Rinse off the plastic when done in that area and remove the plastic

  • Rinse plants again and then re-tarp until finished with job and rise before you leave.


I’m a new guy to this site. I primarily stain fence and outdoor wood. That said, we are getting to the time of year when keeping plants covered for too long with plastic tarps of any kind is risky. It will get hot enough under the tarps (especially in direct sun, sometimes less than an hour in TX) to kill the plants. I don’t know enough about the rest of your thread to be helpful. Good Luck

1 Like

@MDA1775 nailed it. I’ve used a big blue tarp as a runoff ramp over beds before. I spring clipped it to the gutter though. Angled it down to sidewalk and the plants had airflow on the back side and were essentially just shaded.

If you have somewhere you can spring clamp a tarp too. Maybe even staple it under the eaves?


That tarp ramp is a great idea. I’ve never done it but will now. Also I wonder how those easy pull up awning stands might work.

What about using something like this to hold the tarp against the bottom of the eve, and the other end on the ground? Then you could just drape/ stake the other end of the tarp of? 3rd Hands Products - FastCap

Like mda, I don’t have any experience with roof washing, but I plan on expanding into eventually.

These are awesome. I used them when I was a contractor to section off rooms with plastic if I was making a mess. I love the idea if there is nothing to clip to. Spring clips attach to my pocket and I already have enough to carry, but again… if there is nothing to clip to… this is better than pulling staples at the end of the project.

I know I’m tarp and spring clamp addicted, but staining deck floors over hot tubs, patios and plant beds I always use to clamp the tarp to the joists under the deck. It was lightning fast worked awesome.

Good ideas! Im heading to the job in the morning. Will try & post a photo or two.