What is soft washing? We often get a lot of questions from customers asking what the difference is between pressure washing and soft washing. We’re here to help answer those questions so you can better understand what soft washing is and how it is used for exterior cleaning jobs. Soft washing, or “soft pressure washing”, are terms used in the exterior cleaning world to describe how something will be cleaned. Most consumers are aware of pressure washing which blasts water out at high rates of speed but unfamiliar with the term soft washing.

Soft washing is a type of low-pressure cleaning process used to clean delicate surfaces on your home. The pressure used from a soft wash system is typically under 100 PSI compared to 3,000+ in a pressure washer. The most common cleaning services that use this cleaning method is roof cleaning and house washing.

What Chemicals Are Used?

The most common chemicals used for this process are sodium hypochlorite (the same chemical used to clean pools) combined with surfactants and water. While there are many other “roof cleaning” chemicals out there in the market, nothing has proven to work as well as the combination mentioned above. These chemicals are mixed to create a specific strength of the mix.

There are many factors that play into the correct strength. The two main factors are:

1. What surface is being cleaned

2. How dirty is the surface being cleaning

Most exterior cleaning companies will use a dedicated soft wash system. This means rigs will consist of one or several pressure washing systems combined with a soft wash system. Most soft wash systems will use a 12v pump, boost pumper, or air pump to deliver the chemicals to be applied to the surface. The wand used for soft washing is usually different from a pressure washing gun. These wands have ends that can be adjusted from a pencil spray to a fan spray. Depending on how dirty and what type of surface is being cleaned will determine the correct spray pattern to be used.

Applying Roof Cleaning Chemicals To A Roof Using Soft Washing Method

What Surfaces Do You Clean With Soft Washing?

The most common type of cleaning using the soft washing method is for roof cleaning. The reason this method is used for your roof is that it applies the biodegradable chemicals combined with soap at low pressure (typically under 100 PSI) which doesn’t damage your roof. If you were to take a 3,000 PSI pressure washer and try to clean your roof then you’ll likely damage your roof and cause more headaches. Even though you’re using low PSI with soft washing, the chemicals used will kill all algae and bacteria living on your roof in a matter of a few minutes. The common type of roof algae being gloeocapsa magma which are the black streaks and spots on your roof. Using the proper ratio of mix and chemicals will safely remove all living organisms on your roof. If done correctly your roof should remain algae-free for at least 3 years. However, some factors can reduce this timeline (location, trees over your house, etc.)

Adjusting Chemicals Based on Cleaning Job

The soft washing process is also used for house washing. The same chemicals used for a roof cleaning are also used for a house wash but typically at a much lower strength percentage. Depending on the company doing the cleaning, there are multiple ways to soft wash when it comes to house cleaning. Some will use a dedicated soft wash system as they would for roof cleaning. Others will use their pressure washing gun equipped with special tools that reduce the PSI of the pressure washer to a safe level for your home. Similar to a roof, you don’t want to pressure wash a home especially if the exterior is vinyl. A pressure washer can damage the siding and/or make oxidation on your siding even worse.

If you’re soft washing as a DYI project, be sure to take extra precautions as you’re dealing with bleach. Always wear protective gear and keep water in case of an emergency. If you have landscaping near or under your roof, always pre-soak and in some cases cover your plants so they don’t absorb the chemicals being used. When in doubt, hire an experienced soft washing company who will get the job done right!