Explore the top 10 eco-friendly roofing options for a sustainable and energy-efficient home.

When considering what makes a green roof, the terminology can be quite confusing. A true 'green roof' refers to a roof that is covered with living plants, much like the fabled Hanging Gardens of Babylon.

Interestingly, this type of green roof isn't necessarily a cool roof. And for an environmentally conscious design, you need your roof to be cool. Here's another perspective: one of the primary contributors to the greenhouse effect is the roof itself. As sunlight strikes the roof, the light is reflected back into the atmosphere, creating the "heat island" effect in urban areas and causing atmospheric degradation. Additionally, if the roofing material lacks proper insulation, it can lead to increased energy use to cool the building, contributing to further environmental concerns.

To be truly green, your roof must also be cool. Want to know what your options are? Continue reading to discover 10 great choices for your eco-friendly roofing needs.

10: Tile

If you're looking for a long-lasting roof, tile might be the ideal choice, with a lifespan that can reach up to 100 years. Popular in warmer climates, its green credentials stem from its natural materials, unique design, and recyclability.

"The curved design is great for ventilation," says Jessica Clark, marketing liaison for the Cool Roof Rating Council.

Roof tiles are available in a variety of colors, including lighter shades that help reflect less heat into the atmosphere. As an added benefit, their weight contributes to better thermal mass, keeping cool air indoors during hot weather.

9: Single-ply Thermoset

A single-ply thermoset roof is made from a membrane derived from oil and natural gas that is cured and bonded to roofing materials, providing a well-sealed and insulating barrier for buildings.

These roofs are prefabricated in the factory, unlike traditional roofs that are built and sealed on-site. According to the Single Ply Roofing Association, their quality is more consistent since they're not constructed at the installation site.

The association states that thermoset membranes are highly resistant to sun damage. Typically black in color, they are also available in white, which is ideal for a cool roof design.

8: Single-ply Thermoplastic

Thermoplastic membranes differ chemically from thermoset membranes, meaning they don’t have to be bound to the same type of material. They are welded together and can contain fire retardants as well as substances that absorb ultraviolet light.

Manufacturers suggest this type of roof is ideal for businesses like restaurants that expel oils via ventilation systems, as the membranes are resistant to oils, animal fats, and bacterial growth. They can also be installed over existing types of roofs when a complete replacement isn't practical.

Typically, these plastic rolls are available in cooler colors like gray or white, and their smooth surface enhances the roof's ability to reflect light.

7: Shingles or Shakes

Shakes and shingles are among the most common roofing materials, but without the right engineering, they're also the least efficient among the cool roofing options. Specifically, they tend to be the least reflective. And a reflective roof is crucial—it should reflect, not absorb, heat.

To make these roofs more eco-friendly, homeowners can request reflective pigment treatments. However, this doesn’t solve all issues: A smooth surface reflects more light than a textured one. Shingles, with their bumpy surface, scatter light in multiple directions. To make them greener, consider painting them a bright white.

6: Roof Pavers

Pavers are specially designed tiles meant for roofs. They're thick—over 2 inches (5 cm)—and the cool varieties reflect at least 78 percent of ultraviolet rays. Plus, they share the same benefits as roofing tiles.

A roof made entirely of pavers is as heavy as a stone roof and can weigh up to 23 pounds per square foot. However, in buildings designed to support such a weight, this heavy roof can offer excellent insulation. If your home can’t support that load, pavers can be used in smaller areas, like balconies.

5: Metal

When considering cool and green materials, a tin roof might not be the first thing that comes to mind. But this isn't the '50s, and we're not talking about traditional metal. As Clark explains, "It's not bare," adding that it's a coated metal instead.

Start with a coated metal surface, paint it a light color, or add reflective pigments, and you have yourself a cool roof. It’s versatile enough to be installed over an existing roof. Clark adds, "It's really durable, and many times the material can be recycled." Plus, you'll end up with a roof that's unique, especially in a world full of shingles.

4: Modified Bitumen (Tar)

You might not immediately think of a cauldron of hot tar as a component of a cool roof, but this isn’t the same tar used by highway departments. The key to its cool factor lies in the modification. "It's modified with a plastic, and layered with reinforcing material," Clark explains. "What truly makes it cool is that it's a cap sheet."

This technology can be applied as a topping to an insulated roof or used as the primary roofing system itself. Some cap-sheet products require methods like torching or hot-mopping to seal the surface, while others come with pre-attached adhesive, much like a giant contact sheet. By removing the need for hot-mopping, these materials can be installed without releasing fumes.

Certain versions of this material are resistant to both fire and wind, and with the right surfacing, they can be classified as genuine cool roofs.

3: Factory-applied or Field-applied Coating

This versatile material can be applied to virtually any type of existing roof, including metal. It can be applied either at the factory or directly on-site. Typically, the coatings are bright white or feature reflective pigments. "Half of the solar energy coming in is infrared light, which is invisible to us," says Clark. "These pigments reflect that infrared energy."

The National Roof Coatings Institute shared that after the roofs on an entire city block in Philadelphia were covered with "highly reflective white coatings," the surrounding air temperature decreased by 1 degree during the intense summer heat.

2: Built-up Roofing

This roofing style is typically seen in more industrial settings. It begins with a flat roof that is then layered with asphalt and materials coated in asphalt. The cool aspect comes from the top layer, which may be made of something like white-colored gravel.

As reported by the National Roofing Contractors Association, this roofing method has been used in the U.S. for over 100 years, and it is commonly referred to as a tar and gravel roof.

The term "built-up" refers to a roof made from at least four alternating layers of tar and reinforcing materials such as glass fiber mats or organic mats. This layered structure gives the roof excellent insulating properties, and with the right choice of materials, it can also qualify as a cool roof.

1: Living Roof

By sealing the roof, adding planters, and choosing resilient plants, you can create a living roof. Yes, that's right—plants on your roof.

While it’s an innovative idea, maintaining a living roof can be quite costly and challenging. To start, you'll need to conduct a structural evaluation to determine the load capacity of your building. After that, you can make informed decisions.

The National Association of Home Builders, after assessing the roofs, concluded that they possess thermal resistance and insulating qualities. However, it's not as simple as just planting it and walking away—it requires ongoing maintenance, much like a garden. And definitely avoid attempting to grow an oak tree on your roof.