How to Clean an Asphalt Roof Safely & Effectively

Welcome to Wash Safe™ Industries. In this step-by-step guide, we're going to teach you how to clean roof shingles safely and effectively using our original eco-safe Roof Wash and cleaning method. While asphalt roofs are most popular, this same guide can be used to clean rubber, slate and concrete roof tiles.  With 15+ years of experience cleaning over 4,500 roofs, we've engineered both technique and formulations to rid properties of pesky, ugly stains from moss, mold, lichen and algae without bleach or harmful chemicals. 

Roof Cleaning Safety & Reminders

Let's get right into cleaning instructions for cleaning your roof. But, before we do, everyone needs to read safety precautions and have an understanding of the safety precations involved.

Use extreme caution cleaning your roof. Be careful on ladders and steer clear of electrical wires. If you are not skilled, comfortable or physically able, contact a professional. If you do not have the proper safety equipment, contact and contact a professional.

Cover and avoid contact with windows, glass and raw metals (copper and aluminum) when spraying. It's best to rinse windows down before and after every cleaning application to avoid run off. If you do not rinse windows after or let the sun bake the formula on glass, etching can occur. While their is a solution for this, save yourself the headache and follow instructins completely.

Avoid contact with eyes and prolonged skin contact. Wear safety goggles and gloves when cleaning to uphold the highest safety standards. Keep out of reach of children and pets. Do not ingest. If swallowed, drink water and seek immediate medical attention.


Before Getting Started, 
You Should Know..

The goal is to clean your roof safely and effectively and the most key component to this process is to coat your roof with Roof Wash, which is not an easy task and can be quite dangerous. The safest way to do this is to use a Transfer Pump to spray your roof. If your roof area is walk-able then a garden-style pump sprayer may be all that is needed - however, a steep roof must be sprayed from the ladder. The safest way to do this is to lean a ladder up on your roof above the gutter line. Be sure to use a ladder stabilizer to prevent the ladder from sliding along the gutter! This is the best spot to spray from. See below for the complete Transfer Pump setup guide.


Our Technician Recommended Garden Pump Sprayer  for small home improvement roof cleaning projects

We like this one from D.B. Smith FIELD KING. It's the 190328 Backpack Sprayer, 4 Gallon.  We recommend this backpack sprayer for its ease of use, efficiency, and excellent build quality. The sprayer offers exceptional spray coverage, making it ideal for large areas and hard-to-reach spots. Its comfortable backpack design, durable construction, and easy cleanup make it a good home improvement investment for any spraying needs. You'll use it again!

Our Technician Recommended Transfer Pump Setup for Commercial Projects and Roof Cleaning Jobs

Here it is! A quick, short list of everything you need for the Transfer Pump Setup. Check back in the future for a complete video on how to assemble the pump system. This is most often used with a professional job as, you will see, it is not a cheap setup. But it's an effective setup that could save your organization a lot of money because it will produce a more rapid application. If you're a homeowner with a walkable, one story roof (and you're comfortable and have the safety equipment needed to get on your roof) then you can use the affordable backpack sprayer pictured here.

A 24-32 Gallon container or a 55 Gallon plastic drum. We like this one from Amazon because it's lightweight, professional-looking, durable and will be long-lasting. A trash can will also do. This is what you are going to mix your formula in. 


If you have a smaller projet (and are using a Garden Pump Sprayer to apply) then you can mix your solution in a 5 Gallon pail.

A hose connector for the container.

A 1-3 horsepower gas water transfer pump. 

A short piece of hose 40” or so to run from the bottom of the container to the inlet on the water transfer pump.

A 50-100 foot garden hose to attach to the outlet of the water transfer pump. We recommend this one by Gukok: it's a Non-Expanding Garden Hose, Ultra Lightweight, Abrasion Resistant, Durable, Kink-Free Garden Hose, RV, Marine and Camper Hose, 100-Feet.


How to Clean a Roof with Wash Safe Roof Wash

Step 1: Determine How Much Roof Wash Solution You Will Need to Make to Clean the Roof

You are going to use 4 oz (1/2 cup) of product for every gallon of water. Each gallon of water will clean up to 250 square feet. For extremely dirty roofs, you want to double that amount to 8 oz (1 full cup) for every 250 square feet. Below is a guide that breaks down how much coverage you are getting from the sizes of containers we sell:


For approximately 3,000 sq ft :

3 lbs treats 3000 sq ft and makes 12 gallons of solution.
Square footage per gallon = 3000 sq ft / 12 gallons = 250 sq ft per gallon.

For approximately 10,000 sq ft :

10 lbs treats 10,000 sq ft and makes 40 gallons of solution.
Square footage per gallon = 10,000 sq ft / 40 gallons = 250 sq ft per gallon.

For approximately 40,000 sq ft :

40 lbs treats 40,000 sq ft and makes 160 gallons of solution.
Square footage per gallon = 40,000 sq ft / 160 gallons = 250 sq ft per gallon.


Step 2: Mix Your Roof Cleaning Solution

When you have your product ratio, you will mix both powder concentrate and water in a 5 gallon bucket, plastic drum or trash barrel. Mix with warm to hot water. Do you have to have warm-to-hot? No.. but it does work best. 9 out of 10 times our Professional contractors are not using hot water because all they have access to is cold. Cold works just fine.  


Stir frequently for 15- 20 minutes to activate the solution. Stirring is absolutely KEY to the success of your cleaning. You NEED to still consistently for 15-20 minutes. You can't mix a little and walk away. We have contractors that will use paint mixers for this or our team uses their power washing wands flipped upside down and held with clamps to mix larger batches. 


Step 3: Prepare to Spray Roof Cleaning Solution with Your Assembled Transfer Pump OR Garden Pump Sprayer

See our complete breakdown of pieces needed to construct a Transfer Pump System above. 


Once the system is assembled, it's time to spray...


Step 4: Turn Pump on and Begin Spraying the Roof with Roof Wash

Apply the solution using the Transfer Pump System. This is best done with 2 people, one person stays with the bucket of solution and pump and one person should be up on the ladder with the end of the hose and a spray nozzle open when starting the pump to create air/solution flow. 


Start by aiming at the highest point and letting the solution run
down over the roof. Be sure to coat the entire roof! There are 2 ways to go about rinsing off the solution.


Step 5: Rinse off stains from moss, mold, algae and lichen using either the Best Results Method -or- Mother Nature Method

For best results: After 15 minutes of dwell time and using our white soft tip nozzle, rinse solution off with the use of a pressure washer. Your pressure washer must always be aimed down the roof using the water pressure at 300-500 PSI max to avoid scarring and simply rinse clean.


"Mother Nature" Method: Another -easier- way for the homeowners out there is letting Mother Nature do the rinsing with gradual results over time. This is also the recommended method for those who are not comfortable or are physically unable to get up on a roof safely. 


In this instance, you'll let the application dry for an hour or two without rinsing then repeat the process. This insures good absorption. Leave the product on for the rain to wash off. You will wait 30 days and do just one more application. After the first significant rainfall, you should see up to an 80% difference. The roof will eventually be 100% clean after more rain. This process works incredible well for heavy, carpet like growth on the roof but is not the best method for the black streaks. You will need to power wash for those.


This is also an incredible effective Maintenance Method for homeowners or contractors. If you pay to have your roof cleaned efficiently, keep the longevity of the clean by doing a simple mother-nature method cleaning every year. If you are doing a "Maintenance Method" application, just do the one application and then one more spaced out after 30 days.


Roof Cleaning Questions? 
We Have Answers...

How do I keep my roof clean throughout the seasons?

You can clean your roof naturally (without pressure washing) by letting the rain do it using the Mother Nature method which is explained above. Apply a coat of Roof Wash yearly or bi-yearly. Consider bi-yearly if water is nearby, if there is a lot of shade or trees, if your roof faces north, if your neighbor is infected or if you live in a humid climate. The best time of year for maintenance cleaning is Fall so winter's rain, snow, sleet, etc; can help clean the roof. No spraying necessary —the rain does the work!

Do I have to clean with warm water or can I use cold? 

Warm is best but you can use cold if you do not have access to warm water. The product works because of the oxygen, it develops when it is mixed with water. The oxygen needs time to warm.

Do I apply the roof cleaner to a wet or dry surface?

Our products are designed to be applied to a completely dry surface. If the surface is wet, it makes it difficult for the product to adhere to it. It's key that the product adheres to the surface in order to go to work on the stains from moss, mold, algae and lichen. A dry surface is optimal for the products to deliver the best results.

Can I apply the product using a pressure washer?

This is a hard NO. You can only rinse with a pressure washer. Foaming action helps the product to stay on the surface to work. Putting it
through a pressure washer or a soap type siphon dilutes the product. It also does not give it enough time to be activated. The product works because of the oxygen. It develops when it is mixed with water. The oxygen needs time to form.

Do you offer a guarantee on your Roof Wash product?

Wash Safe offers a 30-day money back guarantee on all 3LB powder concentrate formulas if product is used according to our instructions provided. We do not offer a money back guarantee on larger sizes because it is advised to try a smaller size before using it for any application. Especially in the instance of a professional power washing job, you should not be using the product for the first time on a customer's home. You should be testing the product on your home or a friend of family's before being hired for work. Think of it like hair dye at a salon.. would you want the stylist using the dye on you for the first time in her chair?