<http://schema.org/articleBody>
"   One of the earliest roofing materials was thatch, bundled reeds attached to rafters. Surprisingly weathertight, it is incredibly labor intensive, taking even a skilled thatcher weeks to complete. Later came roofs protected by overlapping slates, clay tile and cedar shakes (below), all of which remain in use today. But the great workhorse of the modern American roof is the asphalt shingle. Used for more than 100 years, it&amp;#039;s a good choice for handy homeowners who want a product they can install themselves. The common denominator in all roofing is that several layers work together as a system--each element from the roof deck on up contributes to resisting weather. Understanding how this system works can help you talk knowledgeably with a contractor, or help you make buying decisions to do your own work. Wind and Rain  All roofing systems rely on an overlap to shed water and resist wind uplift. Asphalt shingles are nailed to each other and to the roof deck. Additional weatherproof insurance is provided by strips of factory-applied adhesive. The adhesive is heat-sensitive, which makes the shingles self sealing. How Much Roofing Material You Need  Shingles and underlayment are calculated in &amp;quot;squares,&amp;quot; or units of 100 sq. ft. The per-square weight of roofing materials can vary signifi\u00ADcantly. That&amp;#039;s true even for asphalt shingles. Lighter versions with a core of fiberglass mat might be 200 pounds per square; heavy felt-based types can weigh 425 pounds. Hand Tools Can Handle It   Few major construction jobs today are undertaken without power tools, but hand tools will suffice if you&amp;#039;re laying down a new roof. Sure, pros use nail guns, but you can get by with a 16-ounce hammer, a utility knife, nail pouch, chalkline and utility snips for cutting drip edge and trimming shingles to shape. If you&amp;#039;re tearing off an existing roof, you&amp;#039;ll also need a shingle-ripping bar to get under and lift shingles, a square-nose shovel or a specialized roofer shovel and a tarp down on the ground where you can shovel debris.  Beyond Asphalt Shingles   &amp;amp;gt; %&amp;quot; style=&amp;quot;padding:2px; background-color:#cccccc;&amp;quot;&amp;amp;gt;Clay Tile Popular in the West, Southwest and in Florida, clay tile lasts nearly forever. But the tiles are extremely heavy. The rafters have to be wide enough to carry the load. Cost: Tiles are expensive, and they have to be installed by a pro. Figure on spending at least $500 per square. %&amp;quot; style=&amp;quot;padding:2px;&amp;quot;&amp;amp;gt;Cedar Used in the Northeast and Northwest, cedar shingles or shakes can go 40 years before being replaced. Shingles are thin, relatively smooth and finely tapered, while shakes are thicker and rustic-looking. Cost: DIY, $200 per square. Pro-installed, $400 per square. %&amp;quot; style=&amp;quot;padding:2px; background-color:#cccccc;&amp;quot;&amp;amp;gt;Steel Panel Used all over the country, the &amp;quot;tin lid&amp;quot; is actually steel-plated with a zinc-tin alloy known as terne. Other panels are coated with a high-tech paint system. Better grades last for several decades, or even a century. Cost: It&amp;#039;s pricey, and installed by pros--set aside $400 to $500 per square.  "^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.popularmechanics.com/home/outdoor-projects/how-to/a2764/4257448/>