There are four types of growth to watch for:
- Algae
- Lichen
- Fungus
- Moss
Algae Growth
- Extensive Algae growth – in both green and black.
- Different colors are evident.
- Dark appearance is a protective layer the algae have developed to protect itself from damaging UV rays.
Algae, Lichen, Fungus
- Evident in this image are Lichen, Fungus & algae.
- Notice the vent metal has inhibited growth. This observation is what initially prompted researchers to finding metals which prevent algae growth.
- Note the algae-free surface on dormer roof. This is due to exposure to the sun, allowing that portion of the roof to dry faster.
Algae Growth
- Extensive algae growth.
- The area below the window is free of algae due metal flashing… run-off of the metal inhibits growth and algae.
- Algae predominantly grow from the bottom up, due in part to the amount of time water is on the roof.
Lichen & Fungus Growth
- Fungus is predominantly at the shingle edges and keyways.
- Left to grow may eventually damage the shingles by lifting them and further inhibiting water run-off.
Moss
- Moss due partly to low slope, shady location, organic material & exposure.
- Water is retained on the roof; thus essentially aiding the growth.
- Organic material needs to be present for growth or moss cannot take root.
- White: Very Low Algae, Moss, Lichen and Fungus Growth
- Yellow: Low Alga, Moss, Lichen and Fungus Growth
- Red: Severe Algae, Moss, Lichen and Fungus Growth
