The simple answer is no, it will do more harm than good, it will remove the protective layer of grit. At the most, use the garden hose and use it lightly.
I would not. Pressure washing a roof can cause damage. Pressure washing will get your roof clean. It will look great when it is finished. The long-term damage is not worth it. Pressure washing causes a lot of damage. There are alternatives that work better and don’t cause damage. Asphalt shingles have granules. The granules protect your roof from many things.
You can have it washed and broom cleaned with a cleaner that removes algae. For algae on siding and fence I use a WINDOW cleaner. It comes off of my siding with a quick spray, rub mop across and rinse clean.
Pressure washing can break edges of shingles that are brittle as well.
It depends on the type of roofing and the shape it is in. You can wash with a low setting if you have a shingled roof. If it is metal it should be fine on a medium setting. But I would wash it unless you are having issues.
The black mold-like stains and streaks that appear on roofs, particularly light-colored asphalt shingles, is actually a blue-green algae (Gloeocapsa magma). Commonly found in climates with warm, humid summers, it does no damage to the roofing, but it certainly does looks bad.
The less expensive solution is to spray wash the roof with a 50 percent mix of water and bleach to get rid of the algae. (No pressure washers, please. They're likely to damage the shingles.) Just be sure to wet your foundation plantings first, and rinse everything in clean water when you're done. Plants don't like bleach, and wetting them with plain water first protects them. You can also cover them with tarps or plastic sheeting, which will protect the soil around your plants as well. Make sure that you create a wide radius around your home to be safe.
Allow the solution to soak into the shingles for at least 15 minutes. If they are severely molded, you may want to give it a little longer. Next, rinse the shingles thoroughly with a garden hose at low pressure. Start from the top shingle and rinse downward to prevent water seepage.
To keep the algae from coming back, insert 6-inch-wide strips of zinc or copper under the row of shingling closest to the roof peak, leaving an inch or two of the lower edge exposed to the weather. That way whenever it rains, some of the metal molecules will wash down the roof and kill any algae trying to regain a foothold on your shingles.
You can probably see this same principle working on roofs in your neighborhood. Look for chimneys with copper flashing; the areas directly below the flashing will be free of any algae stains.
The strips also work on roofs suffering from moss buildup. Just scrub it off first with a brush, then bleach as above.
While asphalt shingles are made to handle heavy rainfall, raindrops are not quite the same as a concentrated beam of water from a pressure washer. Simply put, unless you have it on a low (and much less effective) setting, cleaning your roof with a pressure washer would likely do much more harm than good.
The water pressure won’t damage just the shingles, either. There’s a good chance the jet of your pressure washer could work through the adhesive bond holding your shingles together, or seep into and damage your roof’s fabric underlayment. Plus, pressure washers tend to blast sediment into the air, so it’s likely any dirt you do scrape off your shingles is bound to fall back down onto another section of your roof.
On top of all that, most pressure washers are simply not made for roof work. You could seriously injure yourself trying to lug your pressure washer up a ladder. And once it’s up there, there’s no guarantee the weight of the machine won’t damage your shingles.
I would be afraid the pressure would get some water trapped in-between the shingles and cause mold or leaks. I haven't heard of this being done before. If you need it cleaned, maybe contact a roofing place and ask what they suggest.
If its moss, try getting the Moss Out in the hose attachment bottle and spray it down. Around here in Oregon, people also just use the shaker bottle and give it a good dusting with the powder and leave it on after it stops raining.
Every time I clean my mirrors, they end up having tons of streaks and almost look worse than before I started. What could I use to clean them that won't leave streaks...
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I'm hoping one of the man brilliant posters here will have an idea as to how I can safely remove the tarnish from a copper roof above our front door? It is not too o...
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Hi Diane, it's not a good idea to pressure wash your roof - here's an article that will explain why - https://powerwashingsarasota.com/5-things-you-need-to-know-about-residential-roof-cleaning/
Hello Diane,
Maybe, If it is getting a lot of moss grow, might be time to have it cleaned and sealed, or time to have new roof!
Probably not. It can damage the shingles.
The simple answer is no, it will do more harm than good, it will remove the protective layer of grit. At the most, use the garden hose and use it lightly.
I would not. Pressure washing a roof can cause damage. Pressure washing will get your roof clean. It will look great when it is finished. The long-term damage is not worth it. Pressure washing causes a lot of damage. There are alternatives that work better and don’t cause damage. Asphalt shingles have granules. The granules protect your roof from many things.
You can have it washed and broom cleaned with a cleaner that removes algae. For algae on siding and fence I use a WINDOW cleaner. It comes off of my siding with a quick spray, rub mop across and rinse clean.
Pressure washing can break edges of shingles that are brittle as well.
thanks for the awesome information.
It depends on the type of roofing and the shape it is in. You can wash with a low setting if you have a shingled roof. If it is metal it should be fine on a medium setting. But I would wash it unless you are having issues.
No it will nock off tiles
not unless you use really low pressure on it - https://www.pressurewashersdirect.com/stories/204-How-to-Pressure-Wash-A-Roof.html
https://www.youtube.com/watch?v=f_jbaGCR6oo
No pressure washer. It will damage the shingles.
The black mold-like stains and streaks that appear on roofs, particularly light-colored asphalt shingles, is actually a blue-green algae (Gloeocapsa magma). Commonly found in climates with warm, humid summers, it does no damage to the roofing, but it certainly does looks bad.
The less expensive solution is to spray wash the roof with a 50 percent mix of water and bleach to get rid of the algae. (No pressure washers, please. They're likely to damage the shingles.) Just be sure to wet your foundation plantings first, and rinse everything in clean water when you're done. Plants don't like bleach, and wetting them with plain water first protects them. You can also cover them with tarps or plastic sheeting, which will protect the soil around your plants as well. Make sure that you create a wide radius around your home to be safe.
Allow the solution to soak into the shingles for at least 15 minutes. If they are severely molded, you may want to give it a little longer. Next, rinse the shingles thoroughly with a garden hose at low pressure. Start from the top shingle and rinse downward to prevent water seepage.
To keep the algae from coming back, insert 6-inch-wide strips of zinc or copper under the row of shingling closest to the roof peak, leaving an inch or two of the lower edge exposed to the weather. That way whenever it rains, some of the metal molecules will wash down the roof and kill any algae trying to regain a foothold on your shingles.
You can probably see this same principle working on roofs in your neighborhood. Look for chimneys with copper flashing; the areas directly below the flashing will be free of any algae stains.
The strips also work on roofs suffering from moss buildup. Just scrub it off first with a brush, then bleach as above.
While asphalt shingles are made to handle heavy rainfall, raindrops are not quite the same as a concentrated beam of water from a pressure washer. Simply put, unless you have it on a low (and much less effective) setting, cleaning your roof with a pressure washer would likely do much more harm than good.
The water pressure won’t damage just the shingles, either. There’s a good chance the jet of your pressure washer could work through the adhesive bond holding your shingles together, or seep into and damage your roof’s fabric underlayment. Plus, pressure washers tend to blast sediment into the air, so it’s likely any dirt you do scrape off your shingles is bound to fall back down onto another section of your roof.
On top of all that, most pressure washers are simply not made for roof work. You could seriously injure yourself trying to lug your pressure washer up a ladder. And once it’s up there, there’s no guarantee the weight of the machine won’t damage your shingles.
I would be afraid the pressure would get some water trapped in-between the shingles and cause mold or leaks. I haven't heard of this being done before. If you need it cleaned, maybe contact a roofing place and ask what they suggest.
If its moss, try getting the Moss Out in the hose attachment bottle and spray it down. Around here in Oregon, people also just use the shaker bottle and give it a good dusting with the powder and leave it on after it stops raining.