Cleaning Mildew, Stains from Asphalt Roof Shingles

[snpower]

We live in a semi wooded lot and there are some pretty good dark stained areas on one part of my roof. I've tried various products by several manufactures (30 Seconds Outdoor Cleaner, Scott's Outdoor Cleaner, that have in the past, worked well. on lighter stains. Even at full, non diluted strength - these are not cutting it. I am applying with my 3,000 PSI power washer and a long reach nozzle.

Looking for product/technique recommendations! Thank you!

 

[JimRB]

I get some sort of house wash mix from the pressure washer store. It has some bleach smelling stuff with detergents or surfactants in the mix. I spray it on with the low pressure nozzle, chemical injector hose and let it sit a bit. I wash it off with the high pressure nozzle held a good bit away from shingles. It has worked pretty good on my white shingles on house and barn and on my Mom's brown shingles. Pressure washer is rated at 2,700 PSI. It is not getting clean from high pressure but it needs more pressure than 40 PSI of water hose. Soap Warehouse Brand of House Wash Supreme. I think this is a house brand of the pressure washer store I visit.

Also note that my injector works with a short wand. When I use the long reach 20 feet extendable wand, the long wand does not work with the injector system. Only with the short wand. I get a nice bit of sudsy foam on the roof. Foam does not last long but it is still there working, assuming not working on a hot roof in the sun. On the 4/12 roofs I can walk on the roof. 9/12 I cannot walk. 6/12 on Mom's house is the edge of my walking abilities.

 

[bdhsfz6]

I use these zinc strips along the ridge:

https://www.amazon.com/Zinc-Protect-Strip-Mildew-Prevention/dp/B07QFYH4C1/ref=asc_df_B07QFYH4C1?mcid=146086814c153afe875ace617d5cc938&tag=hyprod-20&linkCode=df0&hvadid=693712983271&hvpos=&hvnetw=g&hvrand=8338699700135660206&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9058761&hvtargid=pla-1002663937110&psc=1

It takes time, but the shingles look almost new after a few months.

We can't use chemicals since they kill the shrubbery around the house.

 

[MAX-24-Dean]

^ this works good.
One of my problems with getting dark stained areas on my asphalt shingles was the oak trees dropping leaves and acorns. Removed oak trees, then placed a new roof after 31 years.

The zinc strips are working good on the north side of my house with a 12/12 pitch. Sunlight on the south side takes care of the problem there.

 

[ponytug]

FWIW: I've also used copper strips along the ridge line, especially for moss. For algae and moss lower down, I have used "Wet & Forget". It probably works on roofs as well. I have never used it on a roof.

Wet & Forget | No Scrub Household Cleaning Products

WET & FORGET | No Scrub, Bleach-Free Household Cleaners. No Rinse Outdoor Cleaners. Weekly Shower Cleaner. Indoor Mold Remover. Spider Killer.

www.wetandforget.com

Walmart, Costco, Ace, etc. Comes in an "extreme reach" spray applicator for use on a hose end to reach roof tops.

All the best,

Peter

 

[civilian]

This is what we have used with pretty good results on shingles. This is a concentrate that you mix 5 water to 1 part Wet-N-Forget. Spray on shingles with a hand held garden sprayer.

https://www.amazon.com/Wet-Forget-Multi-Surface-Concentrate-Original/dp/B0D26FPD4G/ref=sr_1_6?dib=eyJ2IjoiMSJ9.6qWEUIR6a6XRPTSV4I8mXWqmdzm3Kx8ZsSIHVPb6h0BJbTJzjEwrjrr4jsAB911IWxqOV5jPItsQ_yRCNVXemjf-K9sM-Q_kCvIWCVVXyBxkbbL0HCpFFLoit3cW_hQYwwsGsfsTy_TB7sN04vlrFOYBeVtWa1-e6qIY0QyMvnNHDf1FQcTKMmYKotAN4WvMobSXmy006jxUY2ah_06sfHOlt2YkNu5FliMvGVAldXEsQjT5riyX701RS3JS5IH2KylAtW-0PPD7JaU3YfthxV8lJIuwGqi87ELrccECkPM.4sA-QSSOwNVwzgb-5BuKF4ed8zIWcnUkNFo6Kvsl7lM&dib_tag=se&keywords=wet+n+forget&qid=1733278257&sr=8-6

Jon

 

[civilian]

Looks ponytug and I were responding at the same time. LOL Jon

 

[RayIN]

Roll copper strip material 2" wide, fastened near the ridge cap is what I did. Copper kills almost any growing green thing.
Years ago door knobs were made of copper, it kills bacteria.
I put copper sulfate granules in my septic tank, flushed down the commode. It kills tree roots, actually all roots growing in the septic field.
Got a stubborn unwanted tree, scatter a couple handsful of copper sulfate around the drip-line. Next year tree is dead.

 

[oosik]

I had my house re-roofed after 30 years. New shingles have a granular copper mix in the shingle. They have been up there for twelve years now. No stains.

 

[JJT]

"Wet it and forget it", applied with low pressure bug sprayer. It might take two applications applied a few weeks apart. It works just like the name.