How To Clean Moss Off Roof Tiles Step-By-Step

Moss is a type of weed that loves to grow in dark, damp areas. It can develop in the lawn, concrete, garden furniture and the roof. If it starts growing on your roof structure, it can damage tiles and gutters. Moss is likely to grow on north-facing roofs, which receive less sunshine and have a lot of moisture.

terracotta roof tiles covered with moss

The appearance of moss on a roof can lead to long-term problems. Therefore, it’s important to remove it as soon as possible to avoid moisture build-up, which can lead to potential roof structural damage, as well as a blockage in your drainage system. Below, we will show you how to clean it and get moss-free tiles, so let’s get to work!

What exactly is moss?

Moss is a general term for non-vascular herbaceous plants that grow quickly in moist environments. By far, the many types of moss found in the UK are among the most demanding plants on the planet. It’s also one of the fastest-growing, capable of quickly spreading and multiplying across your roof. Most homeowners perceive moss on their roof as a nuisance, comparing it to garden weeds. 

Unlike regular garden weeds, moss is often highly invasive and able to thrive where weeds would fail, and, like many plants, it spreads by releasing spores. Because moss and algae may quickly take root in the dark nooks and crevices between and under the tiles, shingles, or slates, north-facing tiled roofs are especially prone to moss and algae build-up

Roof tiles composed of clay or concrete are especially prone to moss growth. This is because their porous surfaces and their frequent exposure to rain and moist environments provide the ideal conditions for moss to root and spread rapidly.

Why it is a problem

Moss and lichen develop on most roofs, and minor growth spots are usually not an issue. If moss growing is allowed to progress, however, it might pose a threat to the roof for several reasons, such as:

  1. Moss acts like a sponge, soaking up a lot of moisture and keeping your roof wet all the time. If moisture penetrates beneath the tiles, it may destroy the roof’s wooden components, jeopardising structural stability and necessitating costly repairs.
  2. The main advantage of a pitched roof is the ease of draining rainwater due to the slanted inclination. On the other hand, moss can hinder water flow by absorbing moisture rather than allowing it to drain away.
  3. Moss can break off and fall into gutters or downpipes, obstructing drainage. If this problem is not addressed, you may end up replacing parts of or even your whole drainage system.
  4. Roof moss can attract birds and insects, which is not suitable for the aesthetic value of your roof, such as bird droppings. Birds can also dislodge moss, causing it to fall into your gutters or downpipes.

Types of moss 

There isn’t a single type of roof moss, and there isn’t a single approach to get rid of it. You can evaluate the growth patterns of moss and other plants on your roof and then learn how to deal with them on a regular basis. Identifying them correctly allows you to eliminate them properly.

a black tiled roof covered with moss.

Experts have identified more than 22,000 different types of moss. That means there’s a good chance you have multiple moss species growing on your roof. Some varieties of moss grow on the ends of roof shingles and tiles, and if allowed to grow under them, can actually lift them up and away from the roof itself.

Other varieties of moss are connected with trees that grow over the roof, such as maple and birch trees. Others, such as mosses that are known to thrive on decaying wood tile roofs, are linked to specific shingle kinds.

How to clean moss off roof tiles step-by-step

Cleaning moss off roof tiles is a DIY task that requires no special roof moss removal solution or moss killer. Here are the tools and the steps for removing moss successfully.

Tools needed

  • Hammer
  • Roofing nails
  • Ladder
  • Long-handled brush
  • Garden sprayer
  • Garden hose
  • Copper or zinc sheet metal
  • Tree saw

Step 1: Prepare the area

You’ll get dirty, so dress appropriately. Wear old clothes, protective eyewear, rubber gloves, a hat, and slip-resistant footwear. If you’re going to the roof’s peak, bring a safety rope or harness with you. Plastic sheeting should be used to cover neighbouring plantings. Place a ladder in a safe location, take the hose, and begin ascending.

Step 2: Use a low-pressure hose to spray water on the moss to see if it falls off

Put a standard jet adapter to the end of your garden hose to remove moss. Climb a ladder (step or telescopic) to your roof and spray the roofing material downward to prevent water from getting underneath the shingles and tearing them up. 

While cleaning, concentrate on huge clumps of moss because they will break off the easiest. You should not use a pressure washer to remove moss from roof tiles. Pressure washing may cause harm.

Step 3: To remove stuck-on moss, scrub your roof with a brush while it’s still wet

Get a long-handled scrub brush with firm bristles that will scrape the moss off your roof without hurting it. Climb to the highest point on your roof and work your way down. Concentrate on a 90 cm area at a time and scrub in downward strokes with hard pressure on the brush. Continue working your way down your roof until you’ve removed all of the moss.

removing moss from roof with a scrub brush

Walking on your roof should be done with utmost caution because the water can make it quite slippery. If necessary, use a safety harness fastened to the roof ridge. If you don’t want to remove moss from your roof yourself, hire a professional roofing company to do it for you.

Step 4: Spray the moss with a bleach and water combination

Before blending everything together, fill a spray bottle with equal parts chlorine bleach and warm water. Climb to the top of the roof and spray the solution on the mossy spots. Leave the solution on the moss for 15 to 20 minutes before rinsing it off with your garden hose once you’ve applied an even coat. 

Some moss may come off right away, while others will take two to three weeks to fall off. Because bleach can harm other plants and discolour pavement or siding, protect the area beneath your roof by covering it with plastic sheeting

After rinsing off the solution, scrub your roof with a stiff brush to help remove any remaining dead moss.

Step 5: Install zinc or copper sheet metals along the roof tiles to prevent future moss growth

Sheet metals are available at hardware stores. If you don’t have any tools at home for cutting, ask the store to cut the strips to size for you. Using the metal cutting blade on a saw, you will need to cut the metal into strips about 5.1 to 10.2 cm broad and 61 to 91 cm long

Then, install the strips directly beneath the ridge on your roof’s peak and fasten them with roofing nails every 15 cm. If you don’t want huge chunks of visible metal, tuck the strip underneath the first row of shingles so that only 2.5 to 5.1 cm will extend out. Look for shingles with copper particles integrated into them if you need to replace your roofing material because they can help prevent moss from growing.

Step 6: To prevent moss from developing again, prune overhanging tree limbs

Moss thrives on tree branches and limbs in gloomy regions. Examine your roof at various times of the day to determine when it receives shade and which branches are to blame. Use a tree saw to chop little limbs as near the base as possible so that they don’t grow back as quickly. 

If you have thick, heavy limbs, get them removed by a professional service. Large branches should not be removed on your own since they can damage your roof or cause serious injury if they fall.

Roof maintenance tips

Besides cleaning tips, you should know a few more things that will help you keep moss out of your roof.

A close up of moss covering tile roof

1. Clean roof moss on a regular basis

Moss and other organic growths will develop differently depending on the climate where you live. Once you see these growths on your roof, start the cleaning process immediately to get rid of them as soon as possible. Organic growths spread quickly, so the sooner you catch them, the better.

2. Do minor repairs now and then

Mould spores and mildew grow faster on a roof with damaged tiles than they would otherwise. Minor damage can quickly escalate into a significant and costly problem if not addressed quickly. Inspect your roof for damage regularly, especially after bad weather and then replace or repair the tiles as needed.

3. Re-seal, re-prime, and re-paint the tiles when possible

It’s the ideal time to strengthen your tile roof with a fresh coat of sealant, primer, and paint right after you clean it. This isn’t something you should do every time you clean your roof, but keep it in mind and perform it every few years, just after you are done with the roof cleaning.

4. Consider using moss resistant products

After cleaning, roof tiles and slates can be treated with a moss-resistant chemical to help inhibit the return of mosses and algae. This treatment does not entirely prevent new moss growth but significantly limits it. As such, depending on the product quality, you will be free of moss and algae formation for many years.

There are additional anti-moss coatings that can be applied to the roofing. The roof will most likely be primed first, which will take a few hours to dry. The actual coating can be placed on the roofing, and it will then create a smooth moisture-proof barrier that prevents moss from adhering to the tiles or slates.

a tile roof with green moss

To sum up, cleaning moss is absolutely necessary to guarantee the proper functioning of your roof and extend its lifespan. If you are confident, only walk onto the roof and have the required equipment, so follow the tips above, and you are good to go!

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