How To Clean Different Types Of Roof

Most blog posts about roof cleaning give you “general rules” that supposedly apply to any roof. This is sometimes fine, if the scope of the article isn’t supposed to be specific. But we thought it’d be helpful to tell you exactly what’s needed for your roof type – whether it’s made of asphalt shingles, clay tiles, metal, or something else.

Read on to find out how to clean...


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Asphalt shingles

Asphalt shingles are cheap, easy to install, and look great. Unfortunately, they’re prone to algae and moss buildup, especially in damp New Zealand conditions. Moss in particular can have a negative impact on the performance of your shingle roof over time, so it’s important to combat it quickly.

To clean asphalt shingles, use a 50/50 mix of laundry-strength liquid chlorine bleach and water. Let this sit for a while, but not so long that it dries. Rinse with water. The next time it rains, most of the algae buildup should disappear, though it sometimes takes a few applications. Never use a pressure washer on asphalt shingles.

Clay and concrete tiles

One of the great advantages of these tiles is that they’re extremely durable. Use the same chlorine bleach mixture described above. You can also use a pressure washer on tiles in most cases.

Tiles are very slippery when wet, and they can also break quite easily if you’re not trained to walk safely on a tile roof. Tile manufacturers often recommend enlisting the help of a professional if you want to clean your tile roof without risking a fall, or breaking a tile

Metal roofing

Metal roofs are fairly easy to clean compared to other types. You can generally use a pressure washer with 100% water, as chemical solutions are usually unnecessary for metal (and sometimes leave unattractive streaks). Wait for a dry, cloudy day to reduce the glare from reflected sunlight, and err on the side of caution: if you’re not sure you can safely reach a given part of the roof, don’t try to do it.


Slate roofs are very attractive, but they require regular cleaning to keep them in good shape. Moss buildup is a particular nuisance, because it can erode the slate and cause it to crack or loosen.

When cleaning your slate roof, you should avoid chemicals. These can take the edge off the slate’s beauty, and erode the heavy-gauge copper components that often accompany slate roofs. You should always avoid walking on a slate roof, as the shingles will easily crack under pressure.

One solution is to use a long extension ladder. Lie it against the roof at an angle which allows it to lie across multiple shingles and spread the load throughout the roof. Use a medium-stiff brush and general household cleaner – nothing too harsh.

Wood shingles and shakes

Wood shingles have a traditional appearance that a lot of people adore. Unfortunately, in wet climates, they’re especially prone to mould and rot. You should inspect wood shingles more often than most other roof types, to make sure excessive moisture isn’t causing any issues.

To clean dirt and most types of growth, use a stiff brush or broom while the roof is dry. This will remove most substances besides mildew. To wash persistent stains, mix a cup of strong household detergent with about four litres of warm water. To get rid of mildew, replace the detergent in the solution above with the same amount of borax.

If all this sounds like too much work, a professional roof cleaner can take the weight off your shoulders. Contact Endeavour Property Services today and we’ll get your roof looking new again in no time – without you having to raise a finger.

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