Metal roofs making a comeback; old asphalt roofs made with toxic lead
The students of the University of Michigan College of Engineering BLUElab Living Building Challenge team discovered something disturbing about our rooftops: they are filled with toxic chemicals and metals that is polluting our rainwater. The students are working to take our Victorian-era net zero energy home and make it net zero water as well. In the process they were testing the rainwater coming from our rooftop. To the team's surprise, the lab results indicated high levels of lead in the water coming from the roof.
Lead and other heavy metals are polluting rainwater
Although the roof was relatively new (installed in 2007), we suspected the asphalt roof shingles were the source of the lead. We brought samples to our friends at the Ecology Center in Ann Arbor, MI for testing. They are the great folks behind HealthyStuff.org where you can find what's in many consumer products. Using an X-ray Fluorescence machine (XRF) they found that the roofing material contained a significant amount of lead and other toxic heavy metals.
Considering most homes use asphalt shingles, this is very concerning. We are turning clean rainwater into toxic waste.
Returning to metal roofs
With rainwater harvesting becoming increasingly popular, metal roofs are making a comeback. They are more expensive, but they are more durable and are a wonderful surface for capturing clean water. Many roofs are now made with Galvalume, an aluminum-zinc alloy coated sheet steel. Galvalume is on the Declare Label which ensure transparency for consumers who want to know what's in the products they buy and that they are safe.
Metal roofs can also be more energy efficient. By using reflective coatings, many metal roofs are earning Energy Star labels by keeping the heat off the roof and reducing cooling costs.
Metal roof options
Metal roofs are now available in many styles. Here's a few for you to consider:
Roof shakes are made from pressed metal, come in a variety of colors and mimic the look of cedar shingles.
Roof tiles are intended to look like Spanish clay tiles. They have the same properties of encouraging airflow, but are less energy intensive to make, weigh far less and are a great water capture surface.
Roof slate looks like slate tiles and, like tiles, they weigh less than their traditional counterpart and can be coated with a reflective material to earn an Energy Star rating.
With these stellar options available, let's all say goodbye to our toxic roofs and start saving up to make the switch to metal.