Re-roofing your home can be one of the most costly renovation projects you undertake. Your roofing material is highly visible, takes a beating from the elements and is partially responsible for your home's heat loss and gain, so choosing a durable, sustainable material should be high on your priority list. I examine some of the most popular roofing types, determine which are the most environmentally friendly and offer tips to help you choose the right roofing material for your home.
Popular Roofing Materials
Is your home really ready for a new roof? If you've called in a professional who has ruled out repairs, you should take some time to research new material options. A sustainable roof protects your home from moisture and leaks, prevents energy loss, lasts for many years and is recyclable. Let's consider some of the most common roofing materials on the market and their "green" factors:
Metal: Although metal roofs are energy-intensive to produce, they are attractive, long-lasting, and often contain high recycled content or are easily recyclable at the end of their lifetime. Choices include steel and light-weight aluminum.
Slate: Beautiful and incredibly durable (your roof will probably outlast your house), slate is also very expensive and heavy. Check transportation distance, as the most slate in the US comes from the Northeast, or look for salvaged slate from architectural salvage yards in your area.
Clay tile: Also known as terra cotta, clay tiles are also extremely durable and water resistant, as well as heavy and expensive. If you're going for a Spanish or Mediterranean aesthetic and have the budget, you can't get more authentic than a real terracotta roof.
Wood shakes: This attractive roofing material is often made of cedar.
Look for shakes without additives, preservatives or moss inhibitors. This is an especially sustainable choice if you live in an area that produces shakes locally, and/or have access to those made from FSC certified wood.
Asphalt shingles: While some manufacturers incorporate a percentage of recycled content, asphalt shingles generally don't last as long as other types of roofing and can cause heat gain, especially if your shingles are a dark colors. It is one of the more affordable materials and therefore the most common residential roofing type, but also one of the least attractive. In other words, asphalt shingles are the vinyl siding of roofing materials.
Concrete tiles: Portland Cement is taxing on the environment to produce, but these tiles are extremely durable. However, they are also heavy which may be an issue, depending on your home's structure.
Fiber cement: This material may look like slate but it is much lighter, as it is made from a mixture of Portland cement and cellulose fiber. It is both weather- and fire-resistant.
Recycled roofing materials: Plastic and rubber are recycled and formed to emulate wood shakes or slate, and the result is a very durable, sustainable roofing material.
Tips for Choosing a Sustainable Roofing Materials
Now that you have a feel for the types of materials available, consider these factors before making your final choice:
Recycled Content. Check to see if the roofing material contains recycled content. Generally, the higher the percentage the better, although durability wins out in the end. Also, confirm that the material can be recycled again at the end of your roof's lifetime.
Coatings. Avoid copper and zinc coated roofing materials, which can wash into water sources and are dangerous to aquatic life.
Maintenance. No one wants to spend a lot of time or money maintaining their roof every year. Be sure your roofing material is durable and that no toxic products are required to maintain it.
Weight. In theory, it seems like the heaviest roof would be the best-both highly durable and unlikely to tear away in high winds.
However, you must be sure that your home's existing structure can support the weight of a new roofing material.
Roof Slope. Is your roof nearly flat, low-slope or high-slope? Some roofing materials perform much better than others, depending on the application.
Color and Reflectivity. If you live in a particularly hot climate, look for roofing materials that are light in color and have high reflectivity. They will bounce more of the sun rays rather than heating your home like an oven.
Warranty. Select roofing materials with the longest warranty possible. It's true, you get what you pay for, and though you may have to fork over more upfront for a sustainable roof, it will pay for itself over time.
Aesthetics. Although this has nothing to do with sustainability, be sure to choose a roofing material that enhances your home's appearance. Make sure it is period-appropriate if you have a historic home.
A Truly Green Roof
You could choose a green-colored metal or shingled roof, but why not go literally green? Also known as "living roofs," green roofs are flat or low-slope roofs that are partially or completely covered by vegetation, either in the form of grass or other small plants, preferably species native to your area. They also consist of a growing medium and a waterproof membrane.
Although green roofs can be high maintenance and expensive upfront, they offer several benefits, including the absorption of rainwater to prevent runoff; insulation for your home; as well as reducing the heat island effect in urban environments. If you have a small yard or none at all, your green roof can provide outdoor space and raise the value of your home.