How To Remove Moss From Roofs Without Damaging The Surface

Roof Moss Removal

Roof Cleaning

As a property owner, you must carefully determine the method you want to use, considering the softness of most roof surfaces.  As a homeowner and contractor, I will explain the best way to make moss on roof surfaces disappear.

This method will work on most roof types including asphalt shingled roofs.  Asphalt shingled roofs are the most popular covering about 80% of homes here in Western Washington, near the Seattle area.

I am a firm believer in following the leading roof manufactures directions/recommendations for roof moss mitigation.  Moss removal and even roof cleaning done wrong may look good right away, but the damage up close can be devastating. Following the directions for most asphalt shingled roofs for moss removal is how I found this great process.

The Asphalt Roofing Manufactures Association represents the leading manufactures of roofs and they recommend this method as the only way to clean moss from roofs.  Furthermore, I have found many homeowners refer to asphalt shingled roofs as composition roofing, or “comp roofing”. I will explain how to remove moss from roofs without damaging the surface.

Another key point is the important fact that moss roots itself into the roofing surface as it grows.

For example, if you instantly remove the moss by using a brush, you will damage the roof surface.  During the brushing of roof moss, and even if done carefully, the moss will pull the top layer of granular from the roof surface.  This is the first barrier of your roof.

Compromising this barrier can result in rapid granular loss over time.  This is why you should NEVER pressure wash, brush, scrape or use high powered air to remove moss instantly.  In the light of protecting homeowners, in the event you call a professional cleaner please use caution.


In short, many companies that provide roof cleaning disregard the softness of roofing material.  As a result, when driving down the road, it is common to see a professional brushing moss from asphalt shingled roofs.  Or for example, after an imporper roof cleaning having rapid granular loss.

Just Say No To Roof Moss Removal Using Brush

In a certain way I understand why these companies use a brush to remove moss here in the Seattle, Bellevue, Everett area of Washington State.  Moss is literally our state plant. In general, homeowners just want the moss removed instantly.  For that reason, bushing moss carefully provides an instant result.  For the most part the roof looks great from the ground level. But trust me, the damage up close is noticeable.  Soft asphalt shingled roofs can hardly stand one improper cleaning.  Again, this is why I want to share my knowledge of using the correct method.

Sooner or later as a homeowner you will require roof replacement service.  Without doubt this can be expensive.  Why not make your roof last as long as its expected lifetime? This is why it is important to understand how to remove moss from roofs without damaging the surface.

Bleach Moss Removal Solution AKA Soft Wash

Using bleach is the only way to follow the instructions from the leading roof manufactures.  The roof cleaning solution is simple, make it yourself using sodium hypochlorite (AKA bleach) at a rate of 50% bleach and 50% water.  Make sure to wear protective equipment, and be careful when using bleach.  Spray this mix to the roof surface thoroughly using a pump sprayer for the moss to take the bleach.  Adding soap such as Dawn dish soap to the mix will help the bleach and water run slower down the roof surface.  This will keep the bleach in contact with the moss for a longer period.  Leave the bleach on the surface for 20 minutes or more.  Followed by a rinse off using garden hose water.  Repeat as needed until all the moss is no longer green.

Let the Bleach Kill The Moss

Depending on the type of moss present, you can normally expect the moss to turn white immediately.  The moss is now 100% dead and will start dissolving over time.   Mother nature  will do the hard work for you.  The dead moss will dissolve over time and after 60 days or so you will notice a clean roof.  You can spray the bleach and water with a simple 1 gallon or 2 gallon pump sprayer from your local hardware store.  Keep in mind that it takes years and years for moss to grow. For that reason, make sure to have patience during this process.

For best results, make sure to apply this solution when you first see moss.  If the moss is thick, and blanketed on the surface expect to wait longer.  Heavy rain, wind, and the environment will break down the dead moss, and it will dissolve slowly.  Regardless, the before and after results you will experience are incredible.  Let the chemistry do the work!

Professional Moss Removal Opinion

Living in the Seattle area where moss is our state plant (I know moss is not a plant and a fungus) I have learned a lot.  I keep on seeing homeowners and contractors using pressure washers or  brushes to remove moss from roofs.  Sure, the roof looks nice and clean from the ground.  However, the damage up close is devastating.  These roofs will suffer from rapid granular loss and the expected life time of the roof system will be cut short.  Another huge disadvantage is all the alive moss that is blown or swept off the roof is now on all the ground surfaces.  The moss will now spread in the lawn, landscaping, walkways, driveways, and everything else near the roof edge.  Using a brush or pressure washing the moss will remove the moss but not the spores.  This makes the moss return rapidly.  Kill the moss using bleach and water.  It really makes sense once you know your options, and again is why it is important to understand how to remove moss from roofs without damaging the surface.

Roof Cleaning Moss

A Seattle home with asphalt presidential shingled roofing.  Heavy moss present.  “Friends do not let friends brush moss.”  Please if you see anyone brushing a roof like this one, make sure to stop them and take their brush away! It is important to understand that this presidential shingle roof, with a manufacturers life rating of 50 years.  The roof will last 50 years most likely, especially if you know how to remove moss from roofs without damaging the surface.  It is unacceptable to replace a roof when it is not needed.  The amount of energy to remove and replace a roof is large, and not ideal for the environment or the pocket book. -Photo by Jay B. in Ballard, WA

Moss Removal Using Bleach Safely Makes Sense

I have used the water and bleach method on thousands of roofs covered with moss and typically we see 5 years before new moss comes back.  There are several companies that call the water and bleach solution “soft washing”.  If you are looking for a professional roof cleaner or you want to do the process yourself just make sure to use the soft wash method for the best results possible with ZERO damage!  Contact Chinook Services for information on this service if you live in the greater Seattle, Everett, Bellevue area (425)290-8635.

For more details check out this video I made when I first started soft washing roofs.  Additionally, check out the second video below of our roof cleaning crews spraying soft wash to moss, and captured by our drone camera.

Amazing, right? For more information, Chinook has local pages near the greater Seattle area: