Before you think about which material to use, decide if you really need a new roof. Do a roof inspection. Look for:

• Loose, warped or worn roofing material.

• Excessive roofing granules in the gutters (from shingle roofs).

• Discolored paint or peeling wallpaper inside the house (indicates the presence of moisture).

- http://www.lowes.com/lowes/lkn?action=howTo&p=BuyGuide/Roofing.html -