Green Materials Report: Metal Roofing

This post is part of the Green Materials Report series. GBE is providing information on various building materials and what makes them green. Each post focuses on one material. We will be looking at the ingredients in the material, how it is used, what makes it green, and any green product certifications that it has earned. We hope to develop a database of information to help consumers make informed choices about what goes in their buildings. Enjoy the series!

Metal Roofing

Metal roofing is primarily made of steel or aluminum. The metal is rolled into long rolls at a metal processing plant. It is coated with a special coating to prevent rust and painted with special paint that is baked on. The rolls are then shipped to the roofing manufacturer. The manufacturer shapes the rolls of metal into panels or tiles, depending on the type of product being produced, using rollforming machinery or large metal presses.

Metal roofing comes in a wide variety of colors and finishes. It can be made to look similar to asphalt shingles, shake tiles, or slate. The variety of colors is only hampered by the imagination of the end-user.

What Makes It Green

The steel and aluminum that is used to make metal roofing contains 25-30% recycled material, and is fully recyclable at the end of its life. It can be installed directly over an existing asphalt roof system, reducing the need to send the old roof to the landfill.

Metal roofing can assist with energy efficiency. Due to its highly reflective surface, it deflects most of the solar radiation that strikes the roof of a building. Then, depending on the color, it can also re-emit the solar energy that is absorbed, with up to 90% of the energy absorbed being sent back. Reducing the solar heat gain from the roof reduces the energy demand for cooling and allows smaller capacity HVAC systems to be installed.

Green Product Certifications

Energy Star – Metal roofing products, depending on the color of the finish (which determines solar reflectance and emissivity), can qualify for Energy Star certification. “Energy Star qualified roof products must meet minimum initial and aged solar reflectance values. Emissivity is not currently a requirement for Energy Star qualification.” Lighter colors have higher solar reflectance.

Environmental product declaration for roll formed steel panels for roofs and walls

Health Product Declaration

No health product declaration could be found for this product.

Pros	Cons
Long life (warranted for 20-50 years)	More expensive than asphalt roofing
Light weight	Noisy (depends on installation technique)
Fire resistant	Can be dented by large hail
Saves energy and money	Metal can flex due to expansion/contraction