5 Differences Between a Green Roof and a Rooftop Garden

"Green roof" and "rooftop garden" are often used as interchangeable terms, but they are actually quite different. Here's a breakdown on the major differences between a green roof and a rooftop garden.

1. Green Roofs do more for the environment.

Both green roofs and rooftop gardens provide environmental benefits. Both give sanctuary to animals and insects in urban spaces, and both do their part to improve air quality. But when it comes right down to it, a green roof is designed for maximum environmental benefit. Even the cover a green roof provides means that roofing materials last longer and have to be replaced less often.

2. Green Roofs are lighter, so to speak.

One of the major differences between a green roof and a rooftop garden is that a green roof stretches over an entire roof, while a rooftop garden only has plants on parts of the roof. A normal garden that covered an entire roof would collapse the roof with its weight. Green roofs are designed to be extremely light, and they even use a planting medium that is lighter than soil and doesn't need to be as deep for plants to thrive.

3. Green Roofs reduce a building's heating and cooling costs.

Every building is different, and every green roof will provide different benefits depending on specific measurements like depth of planting medium. That being said, a green roof will most certainly help your building retail heat in the winter by acting as a natural insulation. In the summer, the cover a green roof provides keeps black tar roofs from heating up and increasing cooling costs.

Rooftop gardens, while they do their part to provide shade and partial insulation, will never have the same heating and cooling benefits simply because a rooftop garden does not cover an entire roof of a building.

4. Rooftop Gardens are more decorative.

While green roofs focus on efficiency and lightness, a rooftop garden serves a more aesthetic purpose. Because plants aren't meant to cover an entire roof, a rooftop garden may contain anything from bushes and trees to flowers to vegetable plants.

Because rooftop gardens are created for their beauty, they often feature sitting areas for their cultivators to kick back and relax. Rooftop gardens are more utilitarian in nature, and although pretty, don't usually have the same variety of plant life and open spaces.

5. Rooftop Gardens don't require professional installation.

Because installing a green roof requires a professional knowledge (to keep a building from collapsing), many homeowners choose to create rooftop gardens instead. If you're going to take on a gardening project by yourself, a rooftop garden made with repurposed containers is much cheaper initially and does provide some environmental benefits, particularly if you grow your own produce.

Resources:

Green Roofs: http://www.greenroofs.org/

Great Lakes Water Institute: http://www.glwi.uwm.edu/research/genomics/ecoli/greenroof/benefits.php