• Cost effective!  On average, aluminum is about 7 times more expensive than steel.  In 2011, the cost of steel was approximately 4 and a half cents per pound, while aluminum was  a dollar and 14 cents! http://www.steelonthenet.com/commodity_prices.html 
  and: http://www.metalprices.com/FreeSite/metals/fe/fe.asp  

• Steel has 3 times the thickness as aluminum
  • That means for a common 3-inch square tube, and for the same limit of bending with the same load, the wall thickness of an aluminum tube would need to be more than 3 times the wall thickness of a steel tube

• Pound for pound, steel is better for the environment than aluminum on all four environmental indicators (carbon, energy, air, water). Read more here

•  http://emergencymanagement.wi.gov/mitigation/stories/hm-oakfield_success.pdf

• Wooden structures can be beautiful, but they tend to rot after time. Steel will not rot, and only needs repainting every decade or so!  Also, steel can be painted to match your home, and looks classy!

•  Galvanized steel is highly rust resistant and can last 50+ years when properly  taken care of.

• Metal roofs cannot be penetrated by normal sized hail.  Even larger hail tends to only dent the metal, but gives protection to your home or vehicles.

• Metal roofs are not noisy when it rains. Residential roofs are made of wood, covered by metal, asphalt or tile. The wood absorbs the sound of rain.