Moss Removal From Shingles

Roof shingles can be constructed from a wide range of materials including wood, fibreglass, cement/asbestos and bitumen. They are typically rectangular in shape. Each tile or "shake" is laid overlapping the tile beneath and covering joints thus providing a waterproof roof.

This roof moss removal help page is specifically related to bitumen based shingles as they are one of the most popular roof covering in the United States.

Moss growth tends occur between the shingles or on overlaps and this is where the damage can and often does happen.

The moss gradually grows and pushes up the edges of the flimsy shingles and combined with a strong sunlight can leave them looking deformed. When rainwater washes down the roof it wears away at the curled up edges of the shingle, thus reducing the expected lifespan.

If the shingles are already showing signs of extensive damage (which is often more prominant near the lower part of the roof) then it may too late to take preventative action. Otherwise there are a few options to reduce moss growth:

• Manual moss removal
• Installation of copper moss killer roof products
• Use a chemical moss killer
• Allow more sunlight onto the roof to prevent excesive growth (by cutting overhanging trees)

The preferred method of moss removal is to gently scrape it off on a dry day when it can be removed more easily.

Some people prefer to use a pressure washer and in our opinion this method should be used with extreme caution. Not only is there a very real risk of flooding the loft but if the water pressure is too high it will strip off the surface of the shingle and reduce the expected life span even further!. Remember the purpose is to remove the moss not clean the roof.

Further reading

Moss Killer Chemicals
Do Roof Coatings Really Work?
The Truth About Gutter Guards