Updated Jan 13, 2023
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Moss begins its life as tiny, airborne moss spores that connect to various surfaces based on their conditions — preferably, damp zones with little ventilation for complete dryness. Through spore dispersal — by insects and the wind — what was once a small patch of moss can cover a significant area, wreaking havoc on your roof.
With rain to enhance its growth, moss continues to expand and spread across all areas, including trees, lawns, and, most commonly, rooftops.
Continue reading to learn how to remove moss from roof tiles, the wide varieties of moss killers, and keep your roof in tiptop condition.
Moss prospers in damp conditions, and roofs are the perfect breeding ground for life. Rooftops are typically shaded by trees or are north-facing, exposing them to little direct sunlight. Clay or concrete tiles are more prone to moss growth due to their porous surfaces and regular rain exposure.
Once moss makes a roof its home, the growth will happen quickly, especially with regular downpours and if you neglect to remove it.
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Preventing a buildup of moss growth is important to avoid destruction and even roof replacement. Here are two reasons to keep your roof in check:
Gathered dead moss on rooftops doesn’t look aesthetically pleasing, but it has a more significant effect than just its inattentive appearance. Moss grows at significant rates, but it doesn’t absorb water. Instead, it sits on top of moisture, leaving your roof constantly wet.
If you fail to remove the moss, rain pour can’t dispel effectively, potentially resulting in wood rot. This creates a spiral effect of other problems, such as termites and tearing through shingles, resulting in you needing a new roof.
Mass moss growth can retain water against the roof’s surface. This water can then freeze and thaw in the winter months, ripping apart tiles. Not only does this create holes in your rooftop, but it’s also a huge safety issue should tiles fall off.
A store-bought roof moss killer stops moss growing in its tracks, and there are a couple of types to look out for.
A liquid algae killer includes a container that connects to a hose, mixing the solution with the water. Liquid roof moss killers engulf the entire roof evenly (more so than dry powders). They’re also a safer application, as your hose might reach the roof without you having to get up there. Or, worst-case scenario, you just need to stand on a ladder to reach.
The one disadvantage of this type of roof moss killer is keeping track of your application. To avoid repeating the same section, you’ll need to mentally monitor where you apply it. Starting with a dry roof is also a big help with this.
When looking for a liquid moss killer, opt for one that’s non-corrosive to metal and, ideally, has a spray nozzle for even application.
These have a slower killing time (up to a week), and they require you to get onto the roof to sprinkle the powder in all the affected areas. However, once you’re in position, the application is less stressful. Simply leave the powder and allow the rain to mix the solution toward the eaves.
It’s also worth bearing in mind that if it doesn’t rain, you’ll need to direct your hose onto the roof. Plus, any gust of wind can blow away the powder, so you’ll have to repeat the application.
Tackle moss without the expense and harsh chemicals by switching to a homemade alternative. Here are two DIY recipes to try:
For any of these moss-killer methods, warmer weather is best, allowing the water to dry.
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Regardless of the moss killer you purchase, you’ll need to get close to the roof, if not on top of it. Here’s how to stay safe:
It’s time to stop the never-ending cycle of moss with steps and applications that will kill it.
Depending on the amount of moss and its persistence, the entire removal process can take up to several hours.
Once there’s no more moss present, there are several strategies to keeping your roof clean. This will help to keep moss at bay, reduce decay, improve your roof’s appearance, increase its lifespan, and, potentially, add value to your home.
Pressure washing can make tiles more porous, increasing dampness for moss to grow. Also, harsh chemicals — like chlorine bleach — can weaken tiles and even cause harm to the landscape and surrounding nature.
Instead, switch to a powerful setting on a hose to target moss areas. Ideally, use as little water as possible to prevent damp areas, and clean your roof on a sunny day for better moisture absorption.
Likely, there are still some moss particles present on your roof. So you might need to get up close and use a scraper to remove anything leftover. Take considerable care not to damage the tiles. Additionally, a brush can remove any remaining debris.
Prevention is better than cure, so here’s how to tame moss growth in the first place:
The best way to stop moss from forming on your roof is to expose your roof to more sunlight. You can’t rotate your house or manipulate the Sun’s position, but cutting back trees and branches prevents them from overhanging onto your roof. Moss doesn’t like direct sunlight, so it won’t appear in the first place.
It’s easy to forget about your roof’s condition and appearance. However, regularly remove branches, twigs, and debris to prevent any restrictions for rain pour to dissipate. You should also keep your gutters free from leaves and sticks to prevent dampness. A dry, sunlit rooftop won’t attract moss in the first place.
Remove moss from roof tiles to prevent damage to your home and potential roof repairs. This flowerless plant is notorious for taking over roofs, impacting your home’s structure.
Frequent roof cleaning can prevent mounds of moss from appearing, and invest in a trusty moss killer to inhibit growth. Alternatively, hire a professional to tackle the job for you.
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