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How To Use A Pressure Washer To Remove Moss

How To Use A Pressure Washer To Remove Moss

So, you have a moss problem.  At first, it didn’t seem like a big deal, but the moss has spread and needs to be removed.  There’s no shortage of ways to remove moss. Suggestions include using bleach, baking soda, or ammonium sulfate. You’ll need gloves, safety glasses, and a bunch of tools.  There has to be a simpler way, right? Wouldn’t a pressure washer be an easier way?

How do you use a pressure washer to remove moss? 

  1. Determine if you can use a pressure washer on the moss covered surface.
  2. Figure out the setting that is appropriate for the surface you are pressure washing.
  3. Use the pressure washer to blast away the moss.
  4. Use a cleaner to better clean the surface or kill moss spores. (Optional)

Before the moss takes over, let’s get started.

Will a Pressure Washer Remove Moss?

Will a Pressure Washer Remove Moss?

Something that pumps out 2,000 to 2,800 pounds per square inch (or PSI) at a rate of 2 to 4 gallons a minute is powerful enough to remove a lot more than moss.  Not only can it be used to clean moss, but people also use pressure washers to get rid of 

  • Loose paint
  • Dirt and grime
  • Algae and mold
  • Chewing gum

On surfaces such as 

Pressure washers are also dangerous because they can bruise or remove skin.  A pressure washer with the highest pressure nozzle can even go through a shoe.  Taking safety precautions is always necessary when pressure washing.

So, yes, a pressure washer will remove moss. But the location of the moss determines whether you should use a pressure washer.

Surfaces Where Moss can be Safely Removed 

Surfaces Where Moss can be Safely Removed

Let’s start with surfaces where you can safely use a pressure washer


Here’s a few things to keep in mind, though.  First, you want to use a low-pressure nozzle. Secondly, you’ll want to spray with the grain.  Pressure-treated lumber is often made from a soft wood, such as southern pine, so you need to be extra cautious about your pressure.  And if you are cleaning a composite deck, using a pressure washer could void the warranty.


Bring it on! 


Brick and mortar are porous, but folks pressure wash it.  Again, avoid the higher pressure nozzles.


That depends. Vinyl and fiber cement siding can take it.  Aluminum dents easily, so most experts recommend against it.  Wood clapboard can also be washed. Avoid washing clapboard siding—it’s easy to knock a shingle loose.

Surfaces Where Pressure Washers are not Recommended

Surfaces Where Pressure Washers are not Recommended

The first one is the most disappointing because it’s a surface moss loves to cover.


Not only can pressure washers hurt a roof, but it’s also potentially dangerous.  The pressure can loosen shingles, strip them of the asphalt granules, and get underneath the shingles.  The blowback from a pressure washer can throw you off balance, which could result in a dangerous fall.


Although people do it, why risk taking off paint when soapy water, a little elbow grease, and a water hose will do the trick?

Copyright protected content owner: and was initially posted on September 18, 2019.


Don’t–unless you want to remove grass and topsoil.

The Best Pressure Washer Settings for Each Surface

The Best Pressure Washer Settings for Each Surface

Use this chart as a quick reminder where a pressure washer and which nozzles are recommended.

SurfaceCan You Use a Pressure Washer?Setting
DecksWooden yes, but composite noLow pressure or 40 nozzle tips
ConcreteYesAny nozzle tip except 0
BrickYesLow pressure, 40 or 25 nozzles
SidingVinyl, fiber, wood yes, but aluminum and clapboard noNothing smaller than a 25 nozzle
RoofsAbsolutely not
CarsNot recommendedLow pressure, if you must

If your moss is on decks, concrete, brick, or siding, you can use a pressure washer to remove it.  However, for grass and roofs, you’re going to have to use another method.

Cleaners to Use Before Pressure Washing Moss

Cleaners to Use Before Pressure Washing Moss

There’s a wide variety of recipes for killing moss, including bleach and water, vinegar and water, or soap and water. Most of those are for smaller applications. When using a power washer to just remove moss, the water should remove it without the use of cleaners or treatments.

Adding soap will help with cleaning the surface while using a bleach and water mixture could kill the mold spores. 

Copyright article owner is for this article. This post was first published on September 18, 2019.

Most commercial cleaners are designed for cleaning roofs, where you can’t use a pressure washer, so stay away from them.

Alternatives to Using a Pressure Washer

On roofs

You’re going to want to get a cleaner that will kill moss and then spray the roof down.  An alternative is a bleach and water solution (50-50 mix) in a pump sprayer. Let the moss die on its own and then spray it off or wait for a heavy rain to do it for you.

Remember that moss loves shade. A preventative strategy is to trim branches or cut down trees so that your roof gets more sunlight.  If you’re a tree lover or can’t afford to have someone remove a tree, you will need to clean your roof every few years.

On grass

Moss on grass is a sign that you need to improve your soil.  This might require raising the pH of your soil, improving the drainage, reducing how often you water, and spot kill smaller patches.

Final Thoughts

Yes, you use a pressure washer to clean moss from many, but not all surfaces.  Please take proper precautions and use the recommended pressure nozzles. Something like 4,500 people wind up in emergency rooms every year from injuries due to carelessness with pressure washers, and you don’t want to be one of those. 

ReadyToDIY is the owner of this article. This post was published on September 18, 2019.

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