So you ask how do I clean my roof. If you’re like me, the days of climbing up on the roof are few and far between but this is also reason enough to pay more attention and get up there to check it out. In other words, the longer you ignore or leave this area untreated, the more it wears and deteriorates until it eventually stops keeping out the rain.

But how exactly can you clean the roof and what chemicals or machines can you use?

Let’s take a look at how to clean your roof and everything you need to get started with the job:

As you may know, I’m a big fan of the jet water and use it at every given opportunity. When the drains or gutters need blasting, it makes an appearance and pressure washers can work wonders on patios, decking, driveways and various jobs around the home.

Alas, using a jet washer to clean the roof is not an option.You see, pressure washers are ten times more likely to remove dirt and debris but they hold far too much power for cleaning the roof. In other words, if you were to use a jet washer to clean the roof, you would most likely damage the shingles and leave the roof even worse than how you found it.

For this reason, the best way to clean your roof is with a sprayer and some cleaning solution.

But before we look any further into the process: what might you find up there that needs to be removed in the first place?

Removing Black Streaks, Dirt and Grime from Your Roof

In case you might be asking yourself, those nasty black streaks on your roof are most likely algae as opposed to dirt and mysterious droppings from the sky. It’s true, you will certainly find dirt and other strange droppings up there but distinctive black streaks are most often the result of algae.

In fact, this algae is even more common during humid weather, when this airborne culprit seems to enjoy nothing more than messing up your roof. By the way, algae is a blue-green growth

Algae is a very common term that describes multiple organisms which require photosynthesis as nutrition. When it comes to the algae on your roof, this is known as Gloeocapsa Magma which has a bizarre ability to hold up a protective shield as protection from UV radiation. What’s more, this blue-green algae is a “colony” which enables it to thrive in areas that most algae cannot even survive. For this reason, when it becomes attached to a surface, it grows and spreads quickly.

Now, in my own language, this simply means that the blue-green streaks on your roof are not going away any time soon. In fact, the only way this will happen is if you get up there to make this happen!

But wait, there’s one more thing you should know about this algae…

The truth is, it doesn’t cause any harm to the roof and unless you have solar panels up there, it’s not something to worry about. That being said, it looks terrible, your neighbors are probably sick of the sight and if you have any respect for your roof, you’ll consider doing it a favour!

But getting back to the task at hand…

What Chemicals Can Be Used to Clean Your Roof?

It’s true that vinegar and baking soda are capable of removing almost anything on your roof but there’s really no need to look any further than bleach.

Bleach is a fantastic agent for this kind of job because it acts like acid rain which can damage almost any living green thing on the planet – things like blue-green algae. At the same time, you don’t want to go overboard with this solution and there are some bleaches that work better than others.

You will find that many contractors use chlorine-bleach which is a very industrious option. However, there is sometimes a risk that, due to the high amount of sodium, this type of bleach can damage the shingles on your roof. In time, this can also make the shingles brittle or stiff and overall, it’s not really the best option.

On the other hand, oxygen bleach causes no damage to the shingles and even allows them to retain their original colour. For this reason, I recommend this type of bleach for cleaning your roof.

How to Clean Your Roof in Five Easy Steps

As already mentioned, jet washers are just too powerful for the roof so in it’s place, you will need a spray gun that you can attach to the garden hose. However, it’s essential that you use the right mixture of water and bleach for the process with 50:50 being the best ratio.

Here are the five simple steps that you need to clean your roof:


  1. Use a brush to remove any large debris that might be on the roof.


  1. Create a 50:50 solution of water and oxygen bleach and pour this into the spray gun.


  1. Spray a section of the roof and then leave the solution on there for at least ten to fifteen minutes.


  1. After this time has passed, use a brush to scrub this section of the roof and continue to wet this surface if it becomes dry during the process.


  1. Rinse off the roof using clean water and continue doing so until the solution disappears.


**Please note you can repeat this process two or three times depending on the outcome.

Want to use your domestic low pressure jet washer?

If you are careful not to dislodge any tiles when jet washing your roof, you can use this method to dislodge any moss clinging to your roof tiles, and wash them down to the gutter line. Here are some very useful pressure washer addons you can successfully use to de moss your roof, clean your conservatory roof, your fascias and soffits and probably more than you can think of .

Karcher sell this very useful telescopic lance, enabling you to reach and wash your roof, conservatory roof, fascias and soffits. Us window cleaners will charge you at least £50 for these services. See this product and read the positive reviews on Amazon here.

Spray an anti moss biocide onto your roof

So you have now demossed your roof, but you know that if you do not kill the spores the moss, lichen and other organic growth will come back. So you need to spray your roof. See the chemicals above that are very effective if used correctly. Here we recommend this chemical sprayer and this telescopic water fed pole, using the two products together, with the wet and go, or forget, (cant remember 🙂 you can clean not just your roof, but neighbours, family and friends, start a little business. Here is the link for the water fed pole and here is the link to the rechargeable chemical sprayer. 

Hiring a Professional to Clean Your Roof

Maybe there’s a reason that you can’t get up there anymore or maybe you just don’t have the time? Either way, hiring a professional to clean your roof is always an option.

Now, you should be able to find several roofing specialists that can get the job done but honestly, this is one sure way to spend a fortune on a rather simple job. Instead, I always recommend friends and family to get in touch with the local window cleaner who has all the right equipment and know-how to do the very same job, for just a fraction of the price.

Needless to say, you should pick someone reliable and agree on a price before they get on with the job. Also, make sure that cleaning up is part of the service and that they keep going until all dirt and debris has been removed.

Either way, I wish you the best of luck and on behalf of your neighbors, thank you for getting rid of those nasty black streaks!

If you have any questions or need any assistance, Reach Wash Cleaning is a local and affordable cleaning service that can get rid of the algae and leave your roof in the best possible shape!

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