Why Is There Green Moss On My Roof

Moisture and organic debris.

Why is there green moss on my roof.

The roots can lift up shingles and constant moisture can lead to bacteria and mold growth. If the moss growth is allowed to develop further it can become a problem for the roof for a number of reasons. If you have moss on your roof it s likely because your roof is shaded by trees or other structures allowing moisture to linger and moss to grow. Left untreated the clumpy greenery can cause virtually any roofing material to degrade most commonly wood and asphalt but also metal clay and concrete and thus drastically shorten its lifespan.

Another critical factor is the amount of shade your roof receives. Moss is a non vascular plant that absorbs water through its leaves instead of roots. Roof shingles are the perfect place for moss and other algae to grow as this part of your home receives the most rainfall and has higher levels of humidity making conditions perfect for moss to thrive. Moss algae and lichen grow on your roof through a combination of two things.

Moss tends to form in areas where it is shielded from the sun. Sunlight reheats the roof evaporating moisture. Lack of sunlight heat and lack of air venting underneath the roof deck. Because moss or lichens growing on a roof surface will hold moisture on the roof longer than other areas these growths can reduce the life of the roof covering.

Moss on a roof begins with a thin dusting of green that you may notice only from low angles. Moss acts like a sponge absorbing large amounts of moisture and resulting in your roof being constantly wet. The seams between the shingles and the shingles edges also develop moss because they tend to be especially shaded. If sections of your roof are under heavy tree cover these are prime spots for moss to thrive.

Moss doesn t always mean you re destined for a whole new roof nor does it mean your home has water or moisture damage. The typical cause is twofold. Moss commonly thrives in environments that are damp and shaded. This thin layer on the top of the shingles expands and becomes wide thick and mat like.

The more water and the more debris the greater the chance of moss growth. If there are large trees near the home that shade parts of the roof moss can grow in abundance as there is a lack of direct sunlight.