It traps rainfall and releases it slowly, so it helps to prevent the flooding that can happen after a storm in a built-up area. It also acts as extra insulation for the building. But its principal virtue is that it’s a haven for wildlife, especially beetles and spiders. In turn these provide food for birds—the black redstart has been encouraged to nest in one part of London as a result of green-roof construction. A recent survey for English Nature found over a hundred species of bugs, some of them rare, in a mixture not found in nature. This has led to the creation of tecticolous as a term to describe this characteristic group (from Latin tectum, a roof).

The building features a “Green Roof” built on top of the parking deck to provide additional outdoor space and help with storm water runoff.

Call County Flat Roofing on 0800 098 8271 or contact us online for more information about how you could have a Green Roof.

[The Capital Times (Madison, WI), 21 Sep. 2004]
“It’s a remarkable thing, having a green roof,” says Jon Alexander, who can stand in his dining room and look out on his planted garage roof in Ballard. “There is this constantly changing show, including wildlife—birds, squirrels, butterflies and bees.”

[The Seattle Post-Intelligencer, 2 Sep. 2004].

What is a Green Roof?

Green roof, eco-roof, nature roof or green roofing system are general terms referring to vegetated roof coverings consisting of a thin layer of living vegetation installed on top of a modified conventional roof system with significant changes. Modern green roof systems replace traditional rooftops; flat or angled up to 45 degrees, with a series of carefully engineered layers. A water and root- repellent membrane is installed on top of a reinforced roof structure. A filter layer is placed between the base membrane and a layer of soil as thin as 1.2 inch thick. Finally the soil layer is seeded with varieties of simple durable plants- sedums, perennial grasses and other "rock garden" plants.

Within a short period of time the entire rooftop is covered with a solid layer of dense vegetation forming an ecologically friendly environment where a potentially harmful one existed. The new roof will perform its intended design functions in an excellent manner, as well as, deliver a multitude of additional benefits.

The green roof concept is akin to the popular, but traditionally heavy and difficult to maintain roof garden found atop buildings worldwide. Roof gardens are nothing new. Gardens for the enjoyment and relief of city dwellers have existed atop buildings for decades. Such roof gardens are expensive to build, often require modification of the structural system of the building to support the increased load and are fairly high in maintenance requirements.

When it comes to roofing, concern for the environment isnt new either. For decades roofing choices have had an environmental and energy impact on civilization. Today, energy efficient and environmentally friendly roof designs are growing in popularity, as even more and more building owners become aware of how much their roofing choices can affect the environment as well as their pocketbooks. Modern green roof systems generally fall into two categories, extensive or intensive, depending on the type of landscape structural burden. Extensive green roof systems are designed for lightweight planting burden construction on flat or sloped roofs. Intensive green roof systems are intended for heavier landscape construction for flat roofs and landscape planters. There are distinct differences in the application and design criteria for the load requirements of each system.

Extensive systems may be installed over any properly designed deck, including Concrete, wood and steel. Typically a vapor barrier or vapor retarder is installed over the deck depending on occupancy and local conditions. Over the vapor retarder or substrate a layer(s) of (optional)thermal insulation is installed. Mechanical fastening of the insulation may be required depending on wind uplift conditions, slope, building height and local codes. The waterproofing membrane and metal flashings are installed to complete the watertight envelope. Decks with slopes of 8 degrees or more may require the installation of landscape retainers at the roof membrane elevation. Intensive systems may be installed over decks designed to accommodate the added load. Typically, concrete decks are the best design choice.

Eco-roofs are becoming fairly common in parts of Europe, principally in Germany and the Netherlands, where green roof technology is well researched and a green roof industry is well developed. The Amsterdam airport has incorporated a sloped green roof into the design of its terminal building. Some cities in Germany now require green roofs on flat-roofed buildings; by 1996 over 3.2 million square feet of green roofs had been constructed in Germany alone.

Green roof technology explores and promotes interest in viable solutions that are aesthetically, functionally and environmentally friendly. It addresses the urgent ecologically demanding issues of air and water quality and storm water management. Green roofs help to invest in the protection of our environment by diminishing developmental impact on our communities while providing a fresh approach with visually appealing organic architecture. The new paradigm, variously known as eco-roofs, green roofs or extensive roof gardens, typically cover the entire roof of a building with a continuous thin growing medium that supports low vegetation. Eco-roofs are lightweight, modern versions of he sod roofs that are a centuries-old tradition in Scandinavia. Because of their light weight eco-roofs require little additional load-bearing capacity from a buildings structural systems; in many cases they may be installed on existing buildings with no structural modification. They do not require flat roofs as do conventional roof gardens but may be installed on roofs with slopes of up to forty-five degrees if provided with a raised grid structure to hold the growing medium in place. Additionally eco-roofs typically require little of no irrigation or fertilizer.

Green roofs create buildings and developments that heal rather than harm the environment. Green roof structures can become net producers of energy, clean water and air, as well as part of healthy human and biological communities.

A Green Roof reduces temperature extremes inside the building. A Green Roof helps to stabilize the temperature inside the building. The soil and vegetation absorb the worst of the heat during the day, cooling the building underneath. In addition, daytime heat is retained after sunset, keeping the building warm at night. A Green Roof intercepts and delays rainfall runoff by:

• Capturing and holding precipitation in the plant foliage
• Absorbing water in the root zone
• Slowing runoff as it infiltrates through the layers of vegetated cover

How has a Green Roof helped the environment (in the U.S)?

Buildings incur a significant environmental impact:

• 65.2% of total U.S. electricity consumption
• More than 36% of total U.S. primary energy use
• 30% of total U.S. greenhouse gas emissions
• 136 million tons of construction and demolition waste in the U.S. (approx. 2.8 lbs/person/day)
• 12% of direct consumption of potable water in the U.S.
• 40% (3 billion tons annually) of raw materials use globally

Sources: USEPA 2001, USGS 1999, WorldWatch 1995.

Call County Flat Roofing on 0800 098 8271 or contact us online for more information about how you could have a Green Roof.

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