How To Clean A Tiled Roof

Learn how to clean moss, algae and general dirt from your tiled roof without using a jet wash.
Written By: Richard Morgan | Updated:
how to clean tiled roof
Richard Morgan/DIY Works

Although all roofs are prone to the build-up of moss, tiled roofs are more susceptible to moss growth as well as algae and general dirt. This, therefore, has a knock-on effect because failing to keep it clean will not only ruin the kerb appeal of your home but it can also cause damage.

Luckily, cleaning your roof tiles is a relatively simple task, but if you can’t do it yourself, many companies offer the service. However, regardless of whether you do it yourself or use a company, you’ll want to avoid pressure washing and instead opt for a soft brush method of cleaning your tiles, which we discuss in this article.

Why You Should Clean Your Roof Tiles

1. Additional Weight On The Roof

Moss acts as a sponge, and if it’s left to retain moisture on your roof tiles, it can become very heavy. Therefore, if you have a lot of moss on your roof that’s collecting water, it’ll cause additional stress (due to its weight) on the roof’s structure.

2. Excess Moisture

Moss retains moisture and grows upon the tiles, so it’ll keep the tiles moist for longer, and this can lead to excess moisture soaking through to the roof’s structure. Over time, this can cause timber rafters to rot as well as damp issues within the attic and fixing these issues can be expensive.

3. Breaks Roof Bonds

The growth of moss is accelerated upon concrete, which means it’ll grow best upon the bonds of the roof tiles (as shown in the image below). Over time, if the moss continues to grow on the bonds of the tiled roof, it can eventually break them, leading to further damage to the roof’s structure.

how remove moss from roof

Richard Morgan/DIY Works

4. Drainage Issues & Blocked Gutters

As mentioned above, moss usually grows upon the bonds, which can also lead to drainage issues. This is because the moss is blocking the drainage path, which can cause standing water when blocked. As well as causing issues with the roof’s drainage, it can also block your gutters as pieces of moss fall from the roof.

5. Overheating of The Roof & Attic

During the summer months, moss, algae and dirt prevent heat from escaping from the roof, making the attic space uncomfortably hot.

6. Aesthetics

Another major factor and the main reason to clean your roof is because it looks dirty and ruins your house’s overall appearance. For example, if you were trying to sell your house, it would ruin its kerb appeal.

How To Clean A Tiled Roof

1. Safe Access To The Roof

The first stage of cleaning a tiled roof is to be able to get to the roof safely in the first place. This can be achieved in several ways, but as shown in the photo, most companies will opt for a scaffolding tower that can be moved to a suitable position.

2. Remove Moss, Algae & Dirt

Once you have safe access to all areas of the roof, you can begin to remove the moss, algae and dirt. The most effective way of doing this is using a trowel or stiff brush to scrape it off. Ideally, the dryer the day, the better because this will make removing the moss from the tiles a lot easier. If it’s too wet, you may find that the moss sticks to the tiles and is more difficult to remove.

how to remove moss from roof

Richard Morgan/DIY Works

3. Soft Wash The Tiles

Once the moss, algae, and other dirt have been removed, the next step is to begin soft-washing the roof tiles.

In short, soft washing is a low-pressure application of a specifically designed roof cleaning product that targets moss, algae and other dirt that’s common on roofs.

As shown in the image, it’s applied by a telescoping water-fed brush that gently scrubs against the tiles. As well as cleaning the roof tiles, another benefit of soft washing is that the cleaning product helps keep the roof cleaner for longer, which is made possible by the formula including an anti-fungicide.

how to clean a tiled roof

Richard Morgan/DIY Works

Should You Pressure Wash Your Roof?

Although using a pressure washer can be very satisfying to use upon patio slabs and other surfaces, it doesn’t mean you should use it on your roof. However, there are still many people who use the machines themselves or hire a company to do it for them. Below are some of the reasons why you shouldn’t use your pressure washer to clean your roof.

should you power wash your roof

Richard Morgan/DIY Works

1. Damages The Tile’s Surface

The main reason why you shouldn’t pressure wash your roof tiles is because it can damage the tile’s surface. The high-powered water can chip away at the tile, and although it would technically clean the roof, it would cause more damage than good. Due to the damage that was caused during the pressure washing of the roof, it would now have a shorter lifespan.

2. Invalidates Any Warranty

Due to the fact that pressure washing your roof tiles has the potential to damage the surface, it’ll more than likely invalidate any warranties. For example, Marley is one of the largest manufacturers of roof tiles in the UK and they specifically state that jet washing your roof tiles isn’t recommended, thus invalidating any warranty you have with them.

3. Only Removes Surfaces Dirt

Unlike using a soft brushing tactic for cleaning roof tiles, when pressure washing the roof, it only removes surface dirt. This means that the algae and lichen spores beneath the tiles will eventually recolonise the roof.

4. Risk Of Dislodging Tiles

As you may need to walk on the tiles and spray high-pressure water at them, you risk dislodging the tiles and damaging the roof.

5. Risk Of Water Entering The Attic

As there may be movements in the tiles, there is a risk that water can find its way through the tiles and into your attic. Therefore, this can lead to further issues, such as dampness and additional leaks if the tiles aren’t put back where they should be.

jet wash roof tiles

Richard Morgan/DIY Works

6. Makes A Lot Of Mess

As with other cleaning tasks that use a pressure washer (i.e. cleaning block paving), it can make a lot of mess. Therefore, all the moss, algae, and other dirt that has been jet-washed off the roof can end up on your driveway or patio. Depending upon the weather conditions, if it’s quite windy, it may also blow onto your neighbour’s property.


Worryingly, we see a lot of companies offering a service of pressure washing roofs, but hopefully, our guide above has shown you why you should avoid it. The process of cleaning your roof tiles with the soft brushing method is not only far safer but also much more effective. If you have any other questions regarding how to clean your tiled roof, feel free to get in touch, and we will try to provide our assistance where possible.

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