Here’s what you need to know: Materials

Materials
Not every roofing material can be used on every roof. A flat roof or one with a low slope may demand a surface different from one with a steeper pitch. Materials like slate and tile are very heavy, so the structure of many homes is inadequate to carry the load. Consider the following options, then talk with your designer and get estimates for the job.

Asphalt Shingle. This is the most commonly used of all roof materials, probably because it’s the least expensive and requires a minimum of skill to install. It’s made of a fiberglass medium that’s been impregnated with asphalt and then given a surface of sand-like granules. Two basic configurations are sold: the standard single-thickness variety and thicker, laminated products. The standard type costs roughly half as much, but laminated shingles have an appealing textured appearance and last roughly half as long (typically 25 years or more, versus 15 years plus). Prices begin at about $50 a square, but depending upon the type of shingle chosen and the installation, can cost many times that.

Source: http://www.bobvila.com/articles/roof-leaking-repair/#.U45cRCiiX94