Moss is a huge problem on asphalt/fiberglass roofs. After only a few years, a new fiberglass laminate roof will have moss growing on the north side of the roof and in the shaded areas. The moss roots itself into the granules on the bottom of each row of shingles and as it grows, it lifts the shingles and destroys them.
Moss usually starts on the top peaks of the roof where the birds like to sit. The original infestation of moss is a by-product of what comes out of the back end of these birds.
Moss has a bi-annual growth cycle in our climate, which is usually in the fall and early spring. In each growth cycle, the moss will double in size as well as spread rapidly over the entire roof. The amount of moss grows exponentially every year. After 1 year, a roof will have 4 times the amount of moss, after 2 years, it becomes 16 times, after 3 years, it becomes 64 times, etc. Moss acts as a sponge and soaks up an incredible amount of water every time it rains. It retains this moisture, keeping the roof damp at all times. It can also cause leaks in the roof by impeding the water flow on the roof.
It is very important to remove all of the moss from the roof including a spray that will kill the moss at its roots. Thereafter, it is recommended that the roof be sprayed with a light coat of moss killer, every year or two. If regular roof maintenance is done, there will never be a major moss problem again.
A) Powerwashing + Application of Moss Killer
This is the quickest and most efficient way to deal with the moss on a roof. The following photos take you step-by-step through the process that usually takes one day, weather permitting.
B) Stiff broom/brushing + Application of Moss Killer
This process takes longer and is not as efficient as power washing. It is the preferred procedure when the roof is very steep or the client does not want a power washer to be used to clean the roof. The following photos take you step-by-step through the process that took six days to complete (including the application of moss killer) with four workers.
The roof on this home is 10 years old, and they have had no maintenance performed on it. The house is nestled among numerous trees and the debris from these trees has fallen onto the roof and exacerbated the problem. As you can see in the photos, we have a veritable carpet of moss that is approximately 3 to 4 inches thick.
On this roof, the brushing alone took four workers 4.5 days to finish. We were able to remove about 80% of the moss but, as you can see, the algae and dirt is still there.
The paler portion of the roof has been sprayed with moss killer within the last five minutes and the moss is clearly dying.
After the treatment has been done, it will take 4 to 6 months before the rain removes the dead moss.