Effects of Moss on an Asphalt Roof

Many people opt to install an asphalt roof on their houses. Asphalt is affordable and doesn't require much expertise to be installed. You can get asphalt in various colors and designs. It also offers high resistance to fire, which is an added bonus towards home security.

However, one issue that frequently affects asphalt roofing is moss. Wet and cold conditions are conducive to the growth of moss. Below are some common effects of moss growth on an asphalt roof.

Increased Wear and Tear

Moss retains water on the surface of an asphalt roof. Consequently moss acts as a catalyst in the wear and tear of asphalt. This effect is especially worse in freezing temperatures, where frost is frequent. Cold climates may cause asphalt shingles to fragment. Gradual cracking and fragmentation of the asphalt shingles tends to occur beneath the moss.

Shorter Life Span of the Asphalt Roof

Quite often as the moss grows, it will weaken the sealing on the shingles. The moss pushes up the asphalt shingles, a condition which causes dislodging and misalignment. Since moss unsettles and fragments asphalt shingles, the roof is unlikely to last as long. Then you have to perform more frequent maintenance, repairs and replacements.


When moss grows more extensively on your asphalt roof, leaks are bound to develop. The moss prevents the water from flowing downward on the roof's surface. Water is diverted to run off the roof in a sideways manner. This condition causes leaking underneath the shingles.

Moss growth can also extend far into the shingles. This situation gives water an opportunity to seep through the damaged areas and into the house. You could eventually be forced into home repairs beyond just the roof.

Mildew and Mold

Because moss tends to soak up water, it keeps the roof wet for a longer period. A wet asphalt roof encourages the growth of mildew and mold. And a constantly wet asphalt roof is more likely to rot because it cannot dry.

When mildew and mold develop underneath the shingles, the damage is likely to extend inward. A musty smell eventually develops in the house when mildew and mold are extensive.

Less Security

As stated above, moss can gradually dislodge shingles. As a result, your house more susceptible to damage by strong winds and severe storms.

Lower Home Value

A strong and secure roof adds value to any home. It is one of the strongest selling points of a house. Unchecked growth of moss will negatively affect the value of your home.