Algae growth is brown or black in colour and results in a streaked, dirty looking rooftop. It's caused by the growth of air-borne algae which deposits on your roof. The good news is that algae growth does not affect the service life of your roofing material. It occurs most often in warm, humid climates such as the SE (where algae-resistant shingles are available).
Moisture or excessive heat in the shingles causes blistering.
Rotting is caused by absorption of moisture by the asphalt or fibreglass mat at the core of the shingle. This is a common problem with organic-based roofing shingles. This is compromise the integrity of the roof.
There are many causes of buckling shingles including: Improperly applied felt, wrinkled underlayment, roof deck movement, spacers not used in between roof deck boards, poor ventilation and new roofing shingles applied over old, damaged shingles. This issue can lead to leaks.
A small amount of Granule Loss is normal, especially after initial roofing application. These granules are called "riders" and are a normal result of the manufacturing process. This should not affect the service life of the shingles unless the loss is extensive, exposing the asphalt or fibreglass mat.
Missing Shingles is a more serious issue caused by improper fastening of the roofing materials or exposure to high winds, You will need to have the affected shingles repaired or replaced. If the damage is extensive you may need a full roof replacement to remediate the issues.
Damaged flashing can be caused by improper roofing installation, drying and cracking on an old roof, denting due to improper nailing, or settling of the structure