Soft washing is one of the roof cleaning methods that roof cleaners and homeowners have been embracing in the recent past. This method is quickly becoming popular because it is gentle on the roof and it is more effective at removing dirt, algae, moss, mold, mildew, and lichen from the surface of your roof, leaving it clean and free of re-infestation.

The following is a guide on what soft washing is, the chemicals, equipment, steps to soft wash a roof, cost, and frequently asked questions.

What is Soft Wash Roof Cleaning?

Soft-wash roof cleaning is an environmentally friendly technique that uses a low-pressure washing technique, as well as a mixture of algaecides, bleach, surfactants, and water, to safely clean dirt from roofs and remove unwanted growths such as algae, moss, mildew, and lichen.

The cleaning is typically done with softwash cleaning systems, which are basically machines designed specifically to help in the application of cleaners to the roof. Soft wash roof cleaning can also be accomplished with a pressure washer set to a low pressure, typically less than 500 PSI.

Soft Wash Roof Cleaning Chemicals

There are several chemicals used in soft wash roof cleaning, each of which serves a different purpose to aid in effective roof cleaning.

The following are some of the most common chemicals used in soft washing roofs:

Sodium hypochlorite (Bleach)

Bleach (sodium hypochlorite) is the primary ingredient in most soft wash cleaning solutions. It kills any mold and mildew spores, algae, moss, and any other plants or fungi growing on the roof. It also penetrates and kills off any root systems in order to prevent further damage to the tiles and to keep anything from growing back.

House hold bleach-ingredients for roof cleaning
Clorox Bleach

Bleach is used in low concentrations, to avoid damaging other roof parts. It is also used alongside neutralisers since it can be harmful to the environment.

Further Reading: How to use Bleach for Shingle Roof Cleaning

Surfactants  (detergents)

Surfactants are essential for achieving a successful soft wash. They are “surface-active agents” that help in cleaning by dislodging dirt, grime, and other contaminants from a surface. Surfactants’ chemical makeup allows them to get between the surface, such as your roof, and the substances that cling to it, such as dirt and fungi. It also improves the ability of the water to wash away these unwanted substances.

In addition, the surfactant will help prevent excessive run-off so the solution will stay on your roof longer for greater effectiveness.

Plant Protectors/ Neutralisers

Some of the chemicals used in soft washing are often toxic to plants and must thus be neutralized for safety.

Chemical plant protectors help to neutralize the soft washing solution and protect the leaves of plants. Moreover, these plant-neutralizing agents can fertilize the plants and leave vital nutrients behind to help them grow.

Odor Maskers

Although bleach is effective at killing organic matter, the odor it leaves behind is not pleasant at all. Odor maskers are typically included to help mask the bleach smell and replace it with a more pleasant scent such as citrus or another pleasing scent.


Biocides are chemicals that are used to kill living organisms, including mold spores, algae cells, and other microorganisms that grow on roofs. In addition to sodium hypochlorite acting as a biocide, soft wash cleaner manufacturers usually include other specially formulated biocides to combat roof microbial growth.


 Soft wash roof cleaners sometimes use soaps as an extra surfactant to help break down stains, as a natural source of biodegradable enzymes, and to help kill algae cells.


 As basic as it might be, water is a very major requirement needed when soft washing roofs. Water helps in diluting chemicals as well as being a vector to the chemicals when cleaning among others uses.

Water is also important in rinsing the solutions and other debris off the roof.

Caustic (sodium hydroxide)

This is a rare alternative cleaner. It is a very potent chemical and should only be used by professionals.

Caustic can burn skin when it comes into contact with it, so use caution when using it.

Roof Soft Washing Equipment

The tools and supplies required for a complete soft wash cleaning process include the following.

Soft wash system or pressure washer

The first thing you’ll need to start soft washing is a functional soft wash system. A soft wash system, at its most basic, comprises a tank for holding the cleaning solutions, a pump and hoses for moving chemicals, a trigger gun for controlling flow, and a nozzle for directing the spray.

If you cannot access a soft wash system, you might opt for a pressure washer instead. You should however make a few adjustments to make it suitable for soft washing.

Make sure you set it to a pressure of 500 PSI or below which is the recommended pressure for soft washing. Anything beyond that ( exceeding 500 PSI), is considered a pressure wash.


Every roof cleaner should have a very sturdy ladder. Without it, there is a significant risk to your safety just from climbing onto the roof. Before trusting a ladder to be safe, factors including where the ladder is set up, how it’s built up, and how tall it is in relation to the roof need to be taken into account.

Further Reading

Extension ladder for rooftop
Extension ladder


Climbing helmets should always be used, not just by the people climbing the roof and working there, but by anybody working underneath on the ground as well. A helmet will help protect you if you fall, if something falls on you, or if you are in danger of bumping your head on an object above as you climb

T-Bar anchor

A T-Bar is a temporary anchor that is simple to fasten to the roof and offers a secure location for the attachment of a rope. A T-bar is used for providing support when cleaning the opposite side of the roof from where it is attached.  The user carefully moves to the opposite side after attaching the rope from the harness to the T-Bar. The T-Bar and rope system is set up to catch them if they fall from the other side of the roof, so they shouldn’t get any injuries from landing on the ground.

Protective gloves

Rubber gloves are required to protect your hands from any hazards that may arise while cleaning.

Sharp debris such as sticks and thorny vines, insects such as spiders, and any sharp or rusted roofing could be a potential hazard to your hands.

Harness and Lifeline

A safety harness and a lifeline rope protect you from falling from a great height. These fall-protection equipment allow you to attach yourself to an immovable object like the T-bar mentioned before, ensuring that if you trip or fall from a height, you will not hit the ground.

Safety goggles

When working, you should think about wearing safety eyewear to prevent injury. Your eyes are at risk from flying debris and chemical splashes when cleaning the roof. Safety goggles  will keep eyes protected from either.

Proper clothing

You should wear long protective clothing when soft washing your roof, mainly for two reasons, to protect yourself from getting hurt by scrapes and scratches and to protect your skin from coming into contact with chemicals and dirt.

Advisably, you should consider wearing old or unused clothing that you would care much about them getting foiled. This is because you might get splashed by bleach which discolors clothing or you mind end up soiled up.

Proper footwear

Although the materials used in roofing shoes vary, a thick rubber sole is best for the tread, which is arguably the most important part of a roofing shoe. Rubber is both durable and malleable, allowing the tread to grip shingles and prevent slips.

How to Soft Wash a Roof

Soft washing a roof is a simple task that usually takes a short while, typically around 30 minutes.

How to soft wash a roof
Roof softwashing

For the best results, follow these simple steps when soft washing your roof

1. Clearing debris

The first step in soft washing a roof is to use a blower to clear away any loose leaves, twigs, branches, or other large debris that may have accumulated on the roof.

Then, using a soft bristle broom or brush, gently remove brush off any thicker, heavier moss that may be present and sweep it off the roof and gutters.

You may not be able to remove all of it, but it is best to remove as much large debris and moss as possible to ensure that the cleaners cover the entire roof and penetrate well.

2. Protect any surroundings plants nearby

Next, you need to inspect your gutter downspouts and properly attach a plastic bag to catch any of the minimal runoff detergent. To protect the vegetation below, make sure to cover all of it well where the chemicals might splash

3. Prepare the cleaning solution.

Prepare your cleaning solution following the manufacturer’s instructions and fill your applicator’s tank(softwash system/pressure washer) with it, as required.

Next your sprayer up to the roof considering all safety precautions and get ready to start.

Make sure your roof is dry before applying the solution. Moisture might make the cleaning solution lose a certain degree of effectiveness.

4. Apply the solution to the roof

Once you are ready, set your pump flow rate such that there’s only minimal run-off into the gutter. And start applying the solution generously all over the roof surface until it is all covered.

It is best to apply the cleaner in and to and fro movement up and down the  roof slope (from the apex to the gutters then) while gently swooshing the spray nozzle sideways. This will help in easy and uniform application. Avoid applying excess solutions to avoid unnecessary runoffs.

A little more attention should be paid to the roof’s apex to ensure that the solution flows underneath the lap joints, which are a favorite hiding place for spores. Without treating the underside of the laps, the target growths frequently quickly recolonize the rest of the roof.

Make sure the spaces between the slates are also completely moistened because they can harbor spores as well as live moss, lichen, and algae.

5. Leave the cleaner to take effect

Once you are fully done, you can now leave to give the chemicals time to work as you clear the area off debris and unneeded equipment.

Algae, which frequently appears as dark stains and black streaks, begins to fade almost immediately after application and is usually gone completely within 20 minutes. Additionally, as the treatment takes effect, the moss will start to change from green to a white or yellow color, signaling that it is beginning to die.

You should be aware that the roof won’t appear clean right away. Instead, the solution will kill the growth, which will then perish and be washed away by rainwater over the next 4-6 weeks.

In order to see the results, you should have the patience to wait until then.

6. Rinse the roof. (Optional)

You should note that not all cleaning solutions are usually left on. Some cleaners usually require to be left on for a specific duration then are later rinsed off with clean water. In such cases you should wait for the required time then rinse the solution and dissolve the grime with a garden hose.


Be aware that some cleaning chemical solutions might be harmful to plants. Make sure the plants are protected from the sprays before you begin washing your roof. You can use plastic sheeting to protect plants close to the walls or roof.

You might also just spritz the plants with water before beginning work when using gentle cleaning agents.

You can also tie garbage bags on all downspouts so that the chemicals don’t spill over to the surrounding areas.

Soft Wash Roof Cleaning Prices/Cost

Apparently, the charging cost of soft washing a roof is typically higher than when pressure washing.

When having a professional do it for you, the charging cost of washing typically ranges from $0.30 to $0.75 per square foot.

Some roof cleaners may add charges as in this instance:

  • Average soft wash  – $0.15 – $0.60
  • Additional story / multi-level roof   + $0.10 – $0.20
  • Steep Roof   + $0.15 – $0.20
  • Roof blow  + $0.05 – $0.10

Soft wash systems are often sold fully assembled or sold in separate parts. A fully assembled professional soft wash kit typically costs about $1000 – $3000.  For individually sold soft wash pumps, they range around $100 – $250.

If you prefer choosing a pressure washer instead, one typically ranges between $100 to $300.

As seen above, soft washing systems are quite expensive, being exclusive of  additional equipment and cleaning solutions prices.

It’d be more cost efficient hiring a professional to do it instead at a fair price because roof cleaning isn’t a regular activity.

Below is how you can soft wash with cheaply available items. All you need is bleach, water, dishwashing soap/detergent, a sprayer and a ladder. Watch the video below for details.


Is it good to soft wash your roof? Benefits?

Soft washing is one of the best ways to clean your roof for great results. Here are some of the reasons as to why you should consider soft wash roof cleaning:

Roof friendly.

A soft wash system reduces the potential damage to the roof when cleaning. Soft washing uses low pressure and cleaning solutions to effectively clean roofs without the need of high pressure.

If you use high-pressure water to clean delicate your shingles roof for example, you may end up with a granular loss, holes or even shingles falling off.  In addition, pressure washing can remove the roof’s coating, which will reduce its ability to reflect sunlight leaving it to degrade fast.

Protects and keeps the roof clean for a long time.

Soft washing not only leaves your roof clean after the job is done, but it also helps to keep it that way for a long time. This is due to the fact that soft wash roof cleaning solutions kill microbial growth on the roof and prevent regrowth or new growths.

Alternative cleaning methods, such as pressure washing, only clean the surface of your roof and do not effectively remove moss, mold, mildew, or algae. There’s always the possibility that they’ll return.

Relatively easy

Soft washing basically makes the job of cleaning roofs easier. This method of cleaning is typically easy as it doesn’t require much elbow grease for example by hard scrubbing and brushing. Soft wash systems can even allow you to spray solution or water the heights of up to 30 feet and thus can save you the trouble of climbing inaccessible areas of your roof from a safe place.

Safe and Eco-Friendly

Soft washing is environmentally friendly and does very little harm to the environment. Most of the soft washing solutions are usually safe to use, biodegradable and eco-friendly. 

This however does NOT mean  that ALL solutions used are safe, some chemicals like surfactants are harmful to any vegetation they come into contact with while some are not good for waterways.

However when used correctly and with caution  there is no need to worry.


Soft wash roof cleaning typically utilizes a relatively small amount of water, for example in comparison to pressure washing.

This is because in Soft washing, one uses chemicals that help in cleaning by breaking down grime and dirt and killing roof growth. This basically leads to low water usage as water is only used in  making the solutions, and sometimes during rinsing.

Does soft washing damage roofs? What are the cons?

Can damage roofing materials

Soft wash roof cleaning is often said to be the safest way to clean your roof effectively while causing no damage. However, If the wrong cleanser or surfactant is used or a strong bleach concentration, it can damage tiles, roofing shingles or other such materials.

Doesn’t remove all stains.

Certain stains may be difficult to remove. This method is great for dealing with all types of grime, but some stains, such as embedded dirt, require the use of a powerful pressure washer.

Time consuming.

Soft wash cleaning is relatively time consuming in comparison to other methods. This is because of the extra cleaning and chemical application.


Compared to pressure washing, soft wash roof cleaning is relatively costlier.

This is because of the additional costs from the extra equipment used and more labor that is required.

Soft wash roof cleaning often requires hiring professionals for the task because most of the equipment used isn’t always readily available for homeowners.

Not effective on some areas

Softwash roof cleaning may not completely eliminate mold and mildew debris and other dirt due to the low water pressure used, necessitating more regular washing. The reduced pressure might not be able to effectively clean dirt and debris out of crevices and difficult-to-reach places. This may require further labor to remove the particles, such as through scrubbing and brushing.


The process of soft washing a roof inclusive of the preparations and assembly is quite a task and requires quite an amount of effort and labor.

Risky to plants

Soft wash chemicals can pose a risk to plants. Soft washing contains only a small amount of sodium hypochlorite (SH), which is the compound that could cause harm to plants.

Without proper precautions, soft washing can damage the vegetation growing around. Chemicals can also spill to drainways and end up in waterways posing a threat to marine life.

What PSI for roof soft wash?

Soft washing is typically done using less than 500 PSI for rinsing or cleaning applications. Any pressure greater than 500 PSI is considered harmful and increases the likelihood of you damaging your roof. The typical pressure used is 100-300 PSI, which is relatively low and will not damage the roof.

Most soft wash systems are set to an ideal pressure. When using a pressure washer to soft wash, make the necessary adjustments or switch to a low-pressure spray nozzle. The pressure washer tip is changed for one that widens the spray, lowering the point of pressure.

Is there a complete soft washing system/machine?

 Yes, there are machines designed specifically for soft washing, which are simply referred to as soft wash systems. A soft wash system, as the name implies, employs a gentler approach, relying on surfactants to remove stains and debris while incorporating low-pressure pumps to reduce the risk of damage.

A soft wash system, at its most basic, consists of a tank for storing chemicals, a pump and hoses for moving chemicals, a trigger gun for controlling flow, and a nozzle for directing the spray.

When soft washing first became popular, chemicals were typically applied with a small 12-volt pump-up sprayer. These basic sprayers were not designed to withstand corrosive chemicals such as bleach, so they ended up wearing out quickly. They could also not shoot very far. Because they produced such low volumes, mixes had to be much stronger than what is now standard.

Today’s sprayers have however improved, most of which bear features like:

  • They are built to withstand sodium hypochlorite and other harsh chemicals.
  • They can shoot up to 30 feet into the air.
  • There’s no need to keep pumping while spraying.
  • Have interchangeable nozzles to achieve the desired spray pattern.
  • Have a consistent and controllable flow
  • Have up to 90 psi pressure.
  • Are extremely versatile and can be used for a wide range of stain-removal products.

Soft wash System Demo

What is a soft wash pressure wash?

A soft wash pressure wash is a method whereby instead of using regular soft wash cleaning equipment to clean, you use a pressure washer for the task with a few adjustments.

For this, you adjust your pressure washers pressure settings to a low-pressure output and switch nozzles to fit the task.

Next, you remove the detergent from the detergent tank and replace it with the soft wash cleaner of your choice. You can also use the main tank to hold the cleaner if it’s one that does not require rinsing after application.

Once done you are ready to go. The next steps are just like when doing regular soft washing. You also can make extra adjustments or add some attachments if necessary like lengthening the hose for increased range and mobility.

Can you soft wash with a pressure washer?

Yes. You can soft wash your roof with a pressure washer. It is completely safe to use a pressure washer as your soft wash system as long as you have the proper tips and working knowledge.

You can soft wash with a pressure washer by setting the PSI (pound-force per square inch) to a low setting. You should strictly use a pressure of 500 PSI or less for soft washing.

If you’re using a professional-grade pressure washer, you may be able to adjust the pressure yourself.

If it doesn’t allow for adjustments, you can change the pressure by switching to a nozzle with less pressure.

Roof soft wash vs pressure wash? Which is better?

Pressure washing and soft washing are some of the commonly used methods preferred by most people when cleaning roofs. While soft washing uses low water pressure and mild chemicals to clean roofs, pressure washing uses jets of water at a high pressure to blast off dirt and debris off the roof.

When it comes to making a choice for the best method to clean roofs, most people prefer soft wash room cleaning for various reasons as explained below:

  • First, soft wash roof cleaning is considered better because the method helps you clean any type of roof safely without causing any damages. On the other hand, pressure washing can damage your roof because of the high pressure used in cleaning.
  • Soft washing is also good because it is often very efficient in cleaning roofs and completely getting rid of organisms like mold, algae moss and lichen, as well as preventing their growth. Pressure washing is often inefficient in getting rid of microorganisms from the roof as it only cleans superficially and uses no chemicals.
  • Lastly, soft wash roof cleaning is better than pressure washing because it saves water. Soft washing uses less water because it incorporates use of cleaners which help increase washing power. On the other hand pressure washing has to use up much water because it relies mostly on water pressure to clean surfaces.

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