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Green Roofs in the United States and Around the World

Green roofs provide a way to reclaim ground space taken up by buildings’ footprints, and they provide several important benefits. In Houston’s urban areas, rooftops are simply unused spaces, and they make up approximately 25 percent of the city’s topography. In Germany and France, green roofs are becoming increasing commonplace, but the United States has been slow to follow suit. However, green roofs can be built atop Houston metal buildings with the help of experienced construction technicians, which should include a Houston foundation contractor and a Houston concrete contractor.

What Is a Green Roof?

Green roofs are far from being new. They were once commonplace throughout Europe and on U.S. prairies during the country’s infancy. For decades, the benefits of green roofs had been forgotten, but they have slowly regained popularity because of their practicality.

A green roof is built by transforming an ordinarily barren space into one that supports vegetative plant life or entire miniature ecosystems. Depending on the specific plants and type of space used, green roofs fall into one of two categories: intensive or extensive.

Intensive green roofs are characterized by a variety of different plants, including trees and shrubs. This type of roof requires substrate layers at least 6 inches in depth and can typically only exist on flat surfaces. The nomenclature for this category derives from the fact that these roofs require intensive maintenance, but all the hard work provides an accessible park-like area.

In comparison, extensive green roofs are only used to grow different varieties of grass, moss, herbs and other drought-resistance plants that thrive with a maximum substrate depth of 4 inches. While these roofs only require minimal maintenance, they are rarely accessible as recreational facilities.

Why Green Roofs?

Researchers around the world, including those at the British Columbia Institute of Technology, have been studying the practical benefits of green roofs, and they have been able to develop some accurate statistics on energy efficiency, storm-water runoff and noise reduction among others.

Urban construction has long been known as a cause of the heat-island effect, where temperatures rise in the inner city after buildings and surroundings absorb heat from the sun. Green roofs provide natural insulation from high temperatures and can reduce heating-and-cooling costs by up to 20 percent.

During large storms, water runs off of buildings and down city streets, quickly collecting at the lowest point, which makes drainage sewers necessary. However, green roofs absorb much of this water, reducing the risk of sewer overflow and maximizing the lifespan of the city’s drainage system.

Finally, green roofs provide a habitable ecosystem for living animals, from insects to birds and small mammals that were displaced by the initial construction.

Green Roofs in Europe

The number of green roofs in the U.S. has been steadily growing since 2010, but it still lags far behind the total number in Europe. However, in 2011, U.S. growth soared from 7.5 million square feet to more than 16 million square feet. In Germany, a full 12 percent of flat-topped buildings are already adorned with green roofs, and the annual growth rate ranges from 10 percent to 15 percent.

Lawmakers in France recently legislated a mandate that all new buildings constructed in commercial zones have either green roofs or solar panels. This has caused a sudden, sharp increase in the number of green roofs in the nation, which has fallen behind other European countries when it comes to environmentalism.

No such laws are planned in the U.S., and the green roof industry is expanding simply upon the knowledge of the benefits provided. In East Texas, a reliable Houston foundation contractor or a Houston metal buildings specialist will be able to offer additional information about green rooftops.