Pressure Washing roofs?!?

[bigbearbear]

Spring is here, yay!

I'm starting to see some of my neighbors using pressure washers to wash their roofs. Isn't that something you shouldn't be doing because the pressure washer will literally reduce the lifespan of your asphalt roof shingles by knocking loose the asphalt?

At first I thought they're using the pressure washer to spray chemicals and/or soap but no, they're literally on the roof and holding the wand next to the roof tile to pressure the roof, which are asphalt type.

I have a contract with this company who comes to my place twice a year and they use a brush to remove any moss on my roof, blow the roof and gutters clean with a leave blower before finally putting down some white powder (baking soda I think) to prevent moss growth. This seems to work well.

What's with folks using pressure washers on their roof? Or is this a legit way to clean your roof?

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[Alexx1401]

I have seen it done for what seems forever. I know if moss is allowed to get out of hand it shortens the life. I would have to "guess" that if someone does not know what they are doing with a pressure washer they could do more damage than the moss? I have long used that liquid concentrate and a water fire extinguisher. Mix the stuff, spray the moss with it. Seems to kill it well since I do not want to climb up there to put the powder stuff on.

 

[The Heretic]

Not recommended for asphalt or shake roofs. Tile is fine, metal I have done (shop). For moss on asphalt use a moss removal chemical.

 

[clearconscience]

Not a good way to keep your roof intact.
Best to blow off or sweep, and throw some moss treatment on

 

[The Heretic]

Not a good way to keep your roof intact.
Best to blow off or sweep, and throw some moss treatment on

Moss is hard to get, even with a broom. Chemicals will loosen it up by killing it. I have sprayed vinegar on my driveway and deck to kill the moss that grows there and that works.

 

[clearconscience]

And/or lined the top with copper

 

[JohnnyMac]

Not a good way to keep your roof intact.
Best to blow off or sweep, and throw some moss treatment on

This is what I've always done (I have metal now), but put some moss killer up there, give it a week or two, then use a stiff broom/brush to remove it. Power sprayer can do more damage than good if not used exactly right. And even then not the greatest for asphalt roofs.

 

[bigbearbear]

Thanks for the various info, I've never had to deal with moss until I moved here to WA last year and it turned into a somewhat interesting research topic for myself.

From what I've read, watched and seen myself, moss is such a fragile plant that even something as harmless (to us) as baking soda kills it. Taking a pressure washer to it seems pretty excessive and unnecessary for roofs. On concrete driveways and sidings, yeah, it is quick and simple but the roof cleaning company I hired simply brush them off and sprinkle baking soda to prevent them from coming back. Very effective so far.

 

[The Heretic]

Baking soda, or vinegar - changes the Ph enough to kill the moss, or weaken it.

Living surrounded by trees and on a mountain where I get twice as much rain, moss and mold are real annoyances up here. I found vinegar works as well as Roundup/Crossbow/etc., even better. Haven't tried baking soda.