Can You Pressure Wash a Roof?

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Can You Pressure Wash a Roof


Your roof takes a battering, it’s predisposed to getting dirty, and those once shiny new roof tiles end up losing their shine. Ultimately they scream at you that they need a deep clean. Even more, when moss, algae, and mildew build-up.

You’ve used your pressure washer to clean your house siding, garden furniture, car, and driveway. So I know when I first started using a pressure washer, I wondered, can you pressure wash your roof? The answer isn’t straightforward, there are some determining factors you need to be aware of.

Is It Safe to Pressure Wash a Roof?

Most people will straight off the bat tell you that it’s not safe to pressure wash a roof, and for the most part, they are right. Your pressure washer is known for getting dirt out of concrete, though they don’t do so well with asphalt, especially when cleaning those shingle sized options.

Can You Pressure Wash a Roof House Roof Cleaning With Pressure Tool

Asphalt shingles – and for that matter, the majority of shingles used in your roof are quite thin. They also have a protective coating applied to them, which protects your home from the weather. Using a pressure washer for cleaning the roof could damage that protective coating. If you want a comparison, think about a rough hail storm, in most cases, they cause some damage to your roof, well your pressure washer acts kind of the same as those hailstones.

Your typical household pressure washer is quite strong. It could cause a lot of damage when cleaning a roof, as it may strip away that protective coating, so while the roof may look clean, suddenly, those tiles can’t do the same job they once did.

Also, you and your pressure washer should be set on a flat dry surface, and the majority of roofs are anything but flat. Standing on a pitched roof isn’t ideal, and with the kickback that you can get from a pressure washer when you pull the trigger. Your balance is already compromised, so kickback isn’t ideal. Plus, as those tiles get wet, you could slip. Unless you are a professional with the right tools, you may be placing yourself in danger.

Is There Still a Way Around It?

I did say that it wasn’t going to be easy and not recommended, but that doesn’t mean it’s not doable. You just need to prepare yourself for the risks, making sure to use the right tools and attachments.

You can’t help the fact that you want a clean roof, wanting to be rid of that lichen and algae, you just have to clean it. I get it. The only recommended method for cleaning roofs is a method called soft washing. This means using a pressure washing unit that has a very low pressure, paired with nozzles that spread that pressure out. So when you clean your roof, you need to use the white and black spray nozzles, these two are the most recommended.

When pressure washing your roof with the right nozzles and power washer, you need to be careful where you step on your wet roof shingles, ideally not stepping on any wet roof shingles, and also, and I stress this avoiding standing on any wet algae, that stuff is incredibly slippery.

If you don’t feel comfortable enough to do some roof power washing, then calling in a professional roof cleaning business makes sense. They know precisely how to move on the roof and how to do this very delicate task. Sometimes it’s worth paying the extra, a professional roof cleaning business will clean your roof better than you can, using low-pressure equipment, making sure that your roof shingles shine and retain their protective coating, meaning no damage and all the algae is gone.

How to Pressure Wash a Roof

If you are going to give it a go yourself, here’s how I do it firstly washing your roof with a pressure washer needs you to take the utmost care and can only be done if you have purchased a low-pressure unit, should you have one here’s how I do it.

1. Cover the Sensitive Areas

Before ascending to the roof. Do you have any plants or sensitive areas around the house? If you do, then I suggest you take the time to cover them. Perhaps you may be thinking “rain doesn’t affect them, why would the water I am using make a difference” The rain water coming off of roofs don’t contain the detergents that are usually used when pressure washing. So when you are power washing your roof, you don’t want that stuff falling down onto your plants. So cover them with a tarp.

2. Attach the Correct Tip

The power coming out of your portable pressure washer may still be enough to cause a fair amount of damage to your shingles, which is why you need to use the right spray tip. I suggest the white or black tips, you want something that is 40-degrees or wider as these are the most appropriate for washing your roof, use these when power washing your roof and you shouldn’t damage your shingles.

3. Spray the Solution

While standing on the dry area of your roof, point your pressure washer down, and before you pull the trigger, make sure you won’t slip off your roof. If you are using a portable pressure washer, the kickback should be minor.

Wet the roof itself with the lowest pressure setting, and spray the roof with some pressure washer roof cleaner, This one by Briggs and Stratton is a great detergent that use can use for your home and is recommended by many professionals. This is capable of killing algae on your roofs and leaving it clean. Give the solution a short period to soak in and allowing it to work.

4. Wash It Off

Once the detergent has sat for long enough, you can wash it off the shingles with clean water, Start from the top of your roof and work your way down, working through each row of shingles washing away any solution. Make sure when you are pressure washing that you use the lowest pressure setting and cover only a few shingles at a time, don’t dwell on a section for too long as it may damage the shingles. Also, don’t spray up under the shingles as it can push water under those shingles, lifting them away, and they could be torn off of your roof.

5. Inspect the Roof

Once you’re done power washing your roof, you need to inspect it and the shingles for any damage caused by the high-pressure water. You should always keep an eye open when you are pressure washing a section. As you water the water hit the shingles, you will be focused properly on that section so you’ll spot damage much easier. Plus, you’ll see whether or not you’ve managed to remove all the algae.

It’s hard to take in an entire roof from a distance, so keep your eyes peeled. A word of warning, do not over-wash your roof. Just clean it enough so that it’s “clean” you don’t need to go mad when pressure washing and aim for a spotless roof. If you wash your roof too often, then you run the risk of wearing your shingles down prematurely.

I have heard some people apply a cars liquid wax to help prevent dirt sticking, I don’t think that’s a good idea, and will cause damage in the long run.

Closing Thoughts

A roof is a delicate part of your home. It takes a battering from the elements, so it doesn’t need one from you, so take care when you are cleaning it. For safety reasons, I honestly suggest you contact a professional first before you attempt to wash your roof. However, if you are set to do it yourself, then follow the steps above thoroughly, and you may well be successful without any injuries.

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Adam White is the founder and chief editor at He has years of experience from years of Gardening, Garden Design, Home Improvement, DIY, carpentry, and car detailing. His aim? Well that’s simple. To cut through the jargon and help you succeed.

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