Photo: Green roofing options

Stay away from asphalt-based roofing materials. (Credit: earthrangers via Flickr)

First, dispose of the old roofing materials.

In Canada, about 1.25 million tonnes of asphalt-based roofing materials are discarded each year. But asphalt shingles are recyclable. Before you hire a roofing contractor, ask if your old shingles will be recycled. For smaller do-it-yourself jobs, look for a construction waste recycling depot near you.

Benefits of metal roofs:

  • Recyclable and often made with recycled content (steel and aluminum)
  • Highly durable, up to 100 years but the screws will only last 25 years
  • Can be installed over asphalt shingles
  • Reflect more energy=lower cooling costs in summer
  • Ideal for water collection; i.e., rain barrels

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Avoid copper roofs, which take a lot of energy to make and create pollution. Also avoid zinc to treat rust; instead, request a powder coating. Finally, ensure your aluminum roof has a baked-on resin that meets national drinking water standards to avoid contaminating runoff.

Benefits of recycled rubber roofs:

  • They're often made from old tires!
  • They're very durable (50 years)

The biggest problems are off-gassing, contamination of rainwater and heat absorption from the black colour (increasing your cooling bill in summer).

Benefits of green roofs (plants growing over a waterproof membrane):

  • Lower cooling costs by 50 to 90 per cent
  • Minimize rainwater run-off
  • Act as a carbon sink
  • Reduce the urban heat island effect (cities regularly reach higher temperatures than the surrounding landscape because of the extra solar energy they absorb)

Today, this is cost prohibitive for most homeowners—starting at $18 a square foot. However, they are becoming more popular on commercial buildings with flat roofs due to their insulating properties, durability, stormwater mitigation and more.

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