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How To Use A Pressure Washer To Remove Moss

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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

Decks

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.

Concrete

Bring it on! 

Brick

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

Siding

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.

Roofs

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.

Cars

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

Grass

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
GrassNo

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. 

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

Best Pressure Washers for Moss

We have three pressure washers to recommend.  Our favorite electric is the Sun Joe SPX3000. Electric models have limited flexibility because they need a source of electricity, so our other choices are gas-powered.  

Sun Joe SPX3000-BLK Electric Pressure Washer

This is our favorite electric model. It has a 14.5 amp/1800-Watt motor.  The PSI is 2030. It has a total stop system (TSS) that cuts off the pump automatically when the trigger is not engaged, and dual detergent tanks. 

What We Like

  • Power cord has a good range.
  • The spray tips can be connected quickly.

What We Don’t Like

  • Too noisy for an electric.
  • The trigger—needs to be gripped firmly, which can get tiring.

Bottom Line

Even though this model, like all electric pressure-washers, is not as strong as a gas-powered machine, we think it is strong enough to remove moss and is capable of doing typical homeowner projects.  It’s price 

Westinghouse Gas Pressure Washer, WPX2700H

We are partial to this model because it delivers the power of a gas machine at a price closer to an electric washer. 2700 PSI at 2.3 gallons a minute is powerful for most applications. The hose is 30 feet long, the spray gun is lightweight, and an on/off valve gives you the option to use soapy water where you want to.

What We Like

  • The thirty-foot hose that lets us do more before we have to move the machine.
  • The large wheels that made moving it easier.

What We Don’t Like

  • The coil mechanism.  Pulling on the starter at an angle often leads to the coil rewind getting stuck. 
  • It didn’t come with a full set of spray tips.  

Bottom Line

We think this model is an excellent choice for a homeowner who wants to clean off moss and more.  It has the power electric mowers don’t, ensuring better results with less frustration. Plus, we like that the price, which is extremely reasonable for a gas-powered machine.

Simpson MSH3125 Gas Pressure Washer

We recommend this pressure washer because of the power and reliability of its engine. It is the strongest machine we recommend at 3,200 PSI at 2.5 gallons a minute.  It is also the sturdiest of the three.

What We Like

  • The 10-inch pneumatic wheels that let us move it over uneven surfaces.
  • The sturdy steel frame.  This is a solid machine that will outlast other washers with plastic or aluminum framing.

What We Don’t Like

  • The location and design of the fuel spout.  Filling it too full leads to spills. 
  • The hose length is 25 feet. With other machines making 30 feet, Simpson could have added five more feet.

Bottom Line

This machine will definitely clean moss as well as most anything a homeowner might need to.  We think this is the machine for you if you have larger projects or plan to use this regularly.

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. 

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