What’s Growing on My Roof?

What you may see as roof discoloration will likely have nothing to do with the color of the asphalt shingles. Whether this color you notice is whitish, greyish, or greenish, it’s some kind of a life form – some roof growth. And it’s not a friend.

The variations of roof growth range from algae and moss to lichens and mold. And they are not only the roof’s enemies; they are your enemies too. Since both your roof and your health are crucial, take a moment to learn more and see what to do.

What are the distinctions between these roof life forms?

roof growth•   Algae – it’s a common roof growth, usually green/blue or green/black in color. It mostly grows on wooden and shake shingles – on asphalt shingles too, when they stay out of the sun for long.

•   Lichens – these are organisms created by the co-existence of fungus and algae, with the former’s characteristics dominating. They vary a lot in terms of appearance and harmfulness.

•   Moss – this is a plant and it grows on asphalt, wood, and shake shingles, absorbing water from its plants rather than roots. It takes a damp environment for moss to grow and thrive, and since it’s thick, it also holds substantial moisture.

•   Mold – it’s often black, green or brown, depending on the species.

•   Mildew – this is quite different compared to mold. It’s found in a powdery form in the natural environment, over roofs – usually when there’s an overhang tree and poor drainage. The colors of mildew range from pink and red to black and green.

How did they find their way on my roof, to start with?

As we have already said, not all types of roofs have the same problems. It also depends on the location, the climate, and the surrounding environment – like in the case of mildew which grows and quickly spreads when there are trees hanging over the roof. It’s fair to say that as a rule of thumb, high levels of moisture create a good environment for roof growths. As a consequence, clogged rain gutters are a bad thing. When was the last time you called for gutter cleaning? Flat roofs where drainage is rather slow and poor would be exposed to the risk of growths too.

What are the roof risks?

roof growthThe roof risks are quite serious if you consider that the high levels of moisture alone – the very reason for the growth of moss or mold, is a sign of a problem around the corner. Take moss, for example. A rather small bush of moss might look cute on the roof but actually it will be the beginning of your problems. The fast growth and spread of moss – a plant that absorbs moisture, may we remind, will also create lots of roof moisture. That’s bad for the shingles – and all roofing types, to be honest. High humidity results in mold growth and the early decay of materials. To make matters worse, when the roof growth has spread, there’s often damage inside the house too. Not only will the roof framing, the shingles, and the other components will be damaged but also the indoor ceiling. And when there’s increased moisture or already mold contamination, the risks go beyond the roof to your health.

Which are the possible health risks?

While roof algae may not directly affect your health, the effects of the growth – most likely mold, will. When the roof growths spread a lot and especially when they affect the inner parts of the house, the health issues are highly likely. High humidity alone is bad for your health – let alone when there’s mold. In such conditions, there might be some allergies, respiratory problems and various health hazards – always depending on the extent of the contaminant and how close it is to the living space.

How to prevent such organisms from growing on the roof?

It makes sense to say that if high humidity is the number one reason for roof growths, the best way to prevent their growth is by eliminating humidity. Of course, this is not always in your hands. And to your defense, such problems may happen when algae spores, for example, land on the roof in a windy day and spread. But what you can do is call a roofer for routine inspection once in a while.

Calling roofers is always the best thing to do whether you want to prevent growth or handle it. That’s because professionals know how to handle the different types of growths on different types of roofs without causing further damage. So, it’s best if you start by finding a local roof contractor.