Why Moss on Your Roof Is Bad, and What You Need To Know

Some roofs may last 20 years while others may last 100 years. You can extend your roof’s lifespan by taking care of it over the years. But if there is moss on your roof, you’re in big trouble.

This is because moss is one of the worst things you can have on your roof. But why? Moss looks relatively harmless, so how can it be such a big problem for your roof?

Keep reading this roof guide and learn more about why steering clear of moss is important for roof maintenance.

Moss Adds Additional Weight and Attracts Mold

Moss might look like harmless tufts of green foliage, but it is much more than that. Moss isn’t your average plant. It is a flowerless plant that loves to grow in cool and damp areas.

You will often find moss growing on the forest floor or the bases of tree trunks. This plant is non-vascular which means that it doesn’t have traditional roots like other plants. This allows it to grow almost anywhere that is damp and cool.

Instead of getting water from its roots, it absorbs it through its green appendages. Because it doesn’t have traditional roots, moss grows wide instead of tall. This gives it more surface area to absorb more water from the air.

Moss is attracted to rooftops that are under the shade of trees or other structures. This makes the roof a cool and moist environment for moss to take hold. Moss is unlikely to grow on roofs that are constantly in the sun.

This environment is too hot and harsh for it.

Some people like the look of moss on their roofs because it looks more rustic. But this is not a good idea. A few patches of moss might not do anything, but it will soon spread.

This will then create more serious problems for your roof. You might not recognize these problems at first. The first issue is that moss adds extra weight to the roof.

The Problem With Moss

You might not think that moss has much weight. If you pick up a piece of moss, it will be soft and light. But the problem is that moss can get very heavy when it grows in a big mat.

When it covers your entire roof, it might add several dozen pounds to the roof. This is similar to having your roof blanketed in snow throughout the year. This is a sure way to weaken the supports in your roof as well as the shingles.

The moss will get twice as heavy once it gets wet. This is because moss is designed to absorb as much water as possible. This can be dangerous for your roof, especially if it is old.

It increases the risk of the roof collapsing under all this weight. Sometimes, wet moss can add hundreds of pounds to your roof. If your roof is new, it should support this weight, but it will drastically decrease its lifespan.

This is why it is important to stop moss as soon as you see it. Moss starts with a single spore. Once that spore takes hold, it will spread across the roof in a short period.

It is best to remove the spore before that happens. Otherwise, it will be much more difficult to remove the moss once it is more developed.

Moss Creates Holes and Increases the Risk of Roof Leaks

While moss doesn’t have very developed roots, it still has some roots. These small roots can be a big problem for the shingles on your roof. As moss grows wider across your roof, it will also grow thicker and more secure.

It does this by extending its root system down into the roof. Roof shingles are dense and aren’t great for roots to take hold. This is why the roots will instead crawl under the shingles.

Mossy roots can do this with ordinary roof shingles as well as roof tiles and slate. Once a single root gets under a shingle, the rest will follow. This will slowly pry the shingle away from the roof’s foundation.

The shingle will eventually fall away, leaving an exposed hole in the roof. If the moss grows wide enough, it might do this with several shingles. This process is very slow and many homeowners won’t notice it at first.

They might only notice the damage once it’s too late and the damage has been done. Some of the shingles might not fall off either once roots grow underneath them. The roots might pop a shingle out of place, but the shingle might fall back into its original space.

This makes the roof look normal, but it is far more vulnerable to damage.

The Extent of the Damage

Once holes start forming in the roof, your roof can sustain a variety of damage. The most common risk is that your roof will develop leaks.

The main purpose of roof shingles is to direct water off the roof. But this won’t work if several shingles are missing. The water will instead stay on the roof and be more likely to seep into the deeper structures.

Once this happens, your roof will sustain permanent damage. This is because the water will soften the deeper layers of the roof as well as the wooden supports. The water will soon soak through until it starts dripping through your ceiling.

This could ruin your ceiling as well. If you don’t notice the leak right away, the dripping water may ruin your floor too. Moss growth can deform your roof in other ways as well.

It may put tension and strain across your roof. This may bend it out of shape and make it more difficult for water to flow off it. This can also increase the risk of roof leaks.

It may also weaken your roof overall. This can shorten your roof’s lifespan by several years. It can also cost you thousands of dollars in repairs and replacement.

Moss Is Ideal for Pests and Terrible for Curb Appeal

Moss is like a magnet for pests. This is because moss is a great foundation for insects to lay eggs. Moss is also a great place for insects and other pests to sit around and set up shop.

Many small insects can live happily in all the little fibers that moss has to offer. Moss offers a very cool and moist environment which is what many insects love. Moss can also attract frogs, salamanders, snails, worms, and so on.

The presence of pests may attract other creatures such as birds, rodents, and so on. Once pests start to get involved with the moss on your roof, it will be hard to get rid of them without also getting rid of the moss.

Moss on your roof will make it more likely for those pests to penetrate the roof’s deeper layers as well. This may cause a serious problem if the moss happens to attract pests like termites. These insects could eat your home from the inside out until there isn’t much left.

Other insects like ants and spiders may make their way into your home through the roof as well. Small mice might like the roof moss as well. Mice can squeeze through many small spaces, so don’t be surprised if mice start coming into your house through the roof as well.

The Details

Moss is also terrible for your home’s curb appeal. If you are selling your house or plan on selling it in the future, you can’t have moss on the roof. You might as well put up a big red flag saying that no one should buy your home.

Moss shows that your home’s roof is uncared for. This is especially true if the moss growth is extensive. It also shows that any new homebuyer would have to put a lot of work into the roof to make it safe again.

Tearing up the moss might permanently damage the roof. This may require it to be repaired or replaced, depending on the extent of the damage.

Removing the moss and starting fresh will make your home look far more attractive.