1 Literacy rate, adult female (% of females ages 15 and above) 2  Literacy rate, adult male (% of males ages 15 and above) 3  Literacy rate, youth female (% of females ages 15-24)  Literacy rate, youth male (% of males ages 15-24)
Asphalt shingles- 30 yrs. (only about 15 yrs. of life, though). Tin- 50-100 yrs. You do the math. Tin is way more expensive, but usually works out to save you over the life of the roof (longer than yours). For Canadian weather, I'd strongly recommend the tin as it sheds snow/rain better. Oh, I'm thinking NW Canada, not sure where you live, but still, tin is the better material all the way around.
1 Flat metal roofs cost $5 to $15 per square foot installed. The actual price paid depends largely on the type of metal you choose.  Keep in mind that the cost of a flat roof is generally cheaper per square foot for larger areas than smaller areas.