Green roofs transform your outdoor space into a sustainable environmental solution that is both practical and beautiful. Essentially, a green roof is exactly what it sounds like: a layer of plants that grows on the rooftop. The description might make you think of the movie The Hobbit, but it's not just for grass houses. With raised garden beds and planters, you can turn any flat roof or small balcony into a green roof. While you might think of it as a feature of hotels, office buildings, and other commercial establishments, you can also have one in your own home.
Over the past 20 years, green roofs have become increasingly popular, especially in urban areas. “From a sustainability perspective, there are heating and cooling benefits,” says Nick Fobes, partner at Hoerr Schaudt Landscape Architects. “But green spaces are also places to enjoy nature and take a break from the buildings and concrete of the cityscape.”
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What is a green roof?
A green roof has several components. Typically, a green roof includes a barrier to prevent water damage to the structure, a drainage system, filter cloth, a lightweight growing medium, and plants. On a small scale, it can be a layer of plants growing on the roof. On a larger scale, it can be a park with trees.
A great example of a large-scale green roof project is the renovation of the iconic Old Chicago Post Office. Built in 1921, the Art Deco building had been abandoned and in disrepair for 50 years. Hoerr Schaudt's landscape design team transformed the roof into a fully-fledged park with 1.5 acres of grass using more than 40,000 plants. It is now a mixed-use office hub with a stunning green roof design that reflects the Art Deco style of the building.
To learn more about green roofs and how you can apply the concept to your home, read on.
Benefits of green roofs
Green roofs are designed to provide both environmental and aesthetic benefits.
Stormwater Management
Green roofs help manage stormwater runoff, allowing it to be absorbed and prevented from overflowing onto non-porous surfaces like concrete, where it would otherwise be washed directly into local rivers and streams, along with any pollutants.
Improving energy efficiency
Green roofs can reduce a building's energy use by cooling the roof, which can extend the life of systems such as heating and air conditioning.
Creating natural habitats
Green roofs attract pollinators and provide habitat for birds and insects, which helps improve the surrounding ecosystem.
Reduce heat and noise pollution
Green roofs help reduce the “heat island” effect in urban areas, where concrete and asphalt absorb solar radiation, and they also absorb sound rather than amplifying it like traditional roofing materials.
Improved quality of life
Building occupants benefit from the beauty that a green roof brings to their outdoor space, bringing them closer to nature and providing a place to gather.
Scott Sigley
Residential green roof by Hoerr Schaudt Landscape Architects
Types of green roofs
There are many different types of green roofs, with different levels of complexity.
Extensive green roofs are simple, using hardy plants such as sedum and a shallow growing medium, requiring little structural support and little maintenance. Intensive green roofs are more complex and resemble a park environment with trees and shrubs, require structural support and require ongoing maintenance.
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How long will a green roof last?
A 2012 University of Michigan study conservatively estimated that a green roof can last for 40 years, more than double the 15-year lifespan of a typical roof.
How much does a green roof cost?
The cost of a green roof can vary widely depending on the type of green roof, the size and scale of the project, and where you live. HomeAdvisor estimates the cost of a green roof to be between $12,000 and $40,000, or $10 to $30 per square foot. Annual maintenance costs average $22,000.
A University of Michigan study found that over the life of a green roof, you can expect to save approximately $200,000 in total, primarily from reduced energy costs.
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How to incorporate the green roof concept into your home
Green roofs are becoming more common in commercial buildings in many cities, but some people are also incorporating them into their homes. While creating a green roof on your home isn't a DIY project, adopting basic green roof concepts can improve any outdoor space, regardless of size, says Fobes.
Make the most of what you have. “Even on a small balcony, you can create a green space,” says Forbes. “Plant intensively and maximize every square foot with plants to create a space that's all yours.” Go big. Small potted plants won't have the same effect. Instead, fill the empty space by putting three large planters of different heights together in a corner. Create a vertical green wall. “Look at all the different surfaces you can grow plants on,” says Forbes. Hang baskets in your windows. This is an easy way to improve your view from indoors and outdoors. Use good design. “Limiting your palette of plants works best,” says Forbes. Instead of using many different types of plants, stick to three. To build your planters, always include a thriller (tall plant in the middle), filler (lower plants to fill in), and spiller (plants that hang over the edge of the pot) technique. Use different textures to add interest. Try self-watering containers. They're handy if you have a sunny environment, since you don't have to check them every day. Fertilize. To keep the flowers blooming, you will need to fertilize the container regularly.
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