First, is a 20 year 3-tab non-AR standard shingle. It is important to
know several things about this type of shingle. It is considered
now-a-days to be a builder grade shingle, meaning it is the thinnest
grade shingle that you can purchase. Also, it is a non-AR shingle,
meaning it is not algae resistant.
Algae resistance is a combination of two elements; copper and zinc.
When these two elements are present in the make-up of the shingle, it
will then ward off about 70% of all molds, mildews and algaes that
cause the black streaking on the roof for a period of about 10 years.
Again, the 20 yr shingle is a non-AR shingle, and for that reason, we
do not recommend this type of shingle for a residential application.
Second, is the 25 year 3-tab AR shingle. This shingle has the same
appearance as the 20 year shingle with these exceptions; it is thicker
and it does have the ar ingredient formulated into its makeup.
It is important to note why a shingle is made thicker. The thicker the
shingle the higher the wind resistance.
Third, is the 30 year AR dimensional (architectural) shingle. It is a
laminated shingle; meaning it is made slightly different than the
standard 3-tab shingle giving it a cottage or cedar shake appearance.
This shingle is quickly becoming the most popular.
Note that the dimensional shingles are also available in 40 year and 50