You’ve probably come across those cute, picturesque paintings of cottages with quaint rooftops that are dabbled with moss – like something that popped straight out of a fairytale. While moss growing on your roof might seem like a great idea, the reality is that it’s more of a nightmare than a fantasy.
That’s because when left untreated, that clumpy greenery will cause virtually any type of roofing material to degrade drastically, shortening its lifespan.
Moss growth will damage clay, concrete, asphalt, wood and even metal roofs when neglected for long periods of time. Moss growth will cause the following problems to your roof:
Displaced shingles. Moss attaches itself to the roof through root-like structures referred to as rhizoids. As the moss plants continue to grow and increase in number, these rhizoids gradually lift shingles up making them loose. Over time these shingles might get blown away by the wind or washed away by rainwater resulting in gaps in your roof.
Increased moisture. Dense moss growth traps a lot of moisture on your roof which could cause your roof to decay.
Leaks. Heavy moss growth can create mini dam-like structures that cause water to back up under the shingles causing the roof to leak. This can cause damage to the underlying roof structure.
Getting rid of moss from your roof
Once you notice your roof has been invaded by moss, there are several control solutions that you can use to remedy the problem.
Hosing the moss down. This is quite a simple method of getting rid of moss. Use a garden hose to hose down moss while scrubbing the roof surface gently with a brush. The process will require a bit of time and effort though. The downside to this (other than using quite a bit of energy) is that you could damage the roof – especially if you have an asphalt shingle roof. Scrubbing the roof could remove the granules that protect the shingles from wear, so be very careful when you do it.
Applying bleach. Spraying a 50/50 mixture of bleach and water (laundry strength bleach can be used too) will kill the moss on your roof. Once the moss has been killed by the solution, you can either hose or sweep the debris away or wait for nature to remove them. Because bleach is acidic, it could discolour your roof or cause it to corrode (more so for metal roofs) causing additional problems.
Applying a biodegradable moss killer. This is probably the easiest and safest way of getting rid of moss from your roof. Biodegradable moss killers are non-acidic and bleach free which makes them ideal for use on the roof as they will not damage the roofing material. All you need to do is apply the water diluted formulation and leave the rest to nature. The added benefit of using a professional moss killer is that your roof will remain protected from moss for some period of time – about 12 months for most products.
Preventing moss growth on your roof
You can prevent moss from growing on your roof by:
Trimming back tree branches to allow sunlight to reach your roof.
Clearing debris from your roof using non-abrasive methods such as using a leaf blower – just make sure you direct the airflow down so as not to blow away the shingles.
Keeping your gutters clear to enable good roof drainage as moss thrives in damp areas.