http://www.outerspacesinc.com/landscapes_swimming_pools_outdoor_living_spaces_main_014.htm OuterSpaces Inc is the Philadelphia Mainline Areas Premier Designer and Builder of Exceptional Landscapes, Swimming Pools, and Outdoor Living Spaces Mon, 15 Mar 2010 20:05:01 GMT Web Easy by Avanquest Software Rooftop Landscape Installation A green roof is a roof of a building that is partially or completely covered with vegetation and soil, or a growing medium, planted over a waterproofing membrane. It may also include additional layers such as a root barrier and drainage and irrigation system. Container gardens on roofs, where plants are maintained in pots, are not generally considered to be true green roofs, although this is an area of debate. Rooftop ponds are another form of green roofs which are used to treat greywater. Also known as “living roofs,” green roofs serve several purposes for a building, such as absorbing rainwater, providing insulation, creating a habitat for wildlife, and helping to lower urban air temperatures and combat the heat island effect. There are two types of green roofs: intensive roofs, which are thicker and can support a wider variety of plants but are heavier and require more maintenance, and extensive roofs, which are covered in a light layer of vegetation and are lighter than an intensive green roof. The term green roof may also be used to indicate roofs that use some form of "green" technology, such as a cool roof, a roof with solar thermal collectors or photovoltaic modules. Green roofs are also referred to as eco-roofs, oikosteges, vegetated roofs, living roofs, and greenroofs. Benefits A modern green roof (California Academy of Sciences). Constructed for low maintenance by intentionally neglecting a wide selection of native plant species, with only the hardiest surviving varieties selected for installation on the roof. Green roofs are used to: Reduce heating (by adding mass and thermal resistance value) and cooling (by evaporative cooling) loads on a building — especially if it is glassed in so as to act as a terrarium and passive solar heat reservoir — a concentration of green roofs in an urban area can even reduce the city's average temperatures during the summer Increase roof life span Reduce storm water run off — see water-wise gardening Filter pollutants and carbon dioxide out of the air — see living wall Help to insulate a building for sound; the soil helps to block lower frequencies and the plants block higher frequencies Filter pollutants and heavy metals out of rainwater Increase wildlife habitat in built-up areas — see urban wilderness Grow fruits, vegetables, and flowers A green roof is often a key component of an autonomous building. A 2005 study by Brad Bass of the University of Toronto showed that green roofs can also reduce heat loss and energy consumption in winter conditions. In a recent study on the impacts of green infrastructure and in particular green roofs in the Greater Manchester area, researchers found that adding green roofs will help keep temperatures down, particularly in urban areas: “adding green roofs to all buildings can have a dramatic effect on maximum surface temperatures, keeping temperatures below the 1961-1990 current form case for all time periods and emissions scenarios. Roof greening makes the biggest difference…where the building proportion is high and the evaporative fraction is low. Thus, the largest difference was made in the town centers.” An intensive roof garden in Manhattan Green roofs can be categorized as intensive, "semi-intensive", or extensive, depending on the depth of planting medium and the amount of maintenance they need. Traditional roof gardens, which require a reasonable depth of soil to grow large plants or conventional lawns, are considered "intensive" because they are labor-intensive, requiring irrigation, feeding and other maintenance. Intensive roofs are more park-like with easy access and may include anything from kitchen herbs to shrubs and small trees. "Extensive" green roofs, by contrast, are designed to be virtually self-sustaining and should require only a minimum of maintenance, perhaps a once-yearly weeding or an application of slow-release fertilizer to boost growth. Extensive roofs are usually only accessed for maintenance. They can be established on a very thin layer of "soil" (most use specially formulated composts): even a thin layer of rock wool laid directly onto a watertight roof can support a planting of Sedum species and mosses. Another important distinction is between pitched green roofs and flat green roofs. Pitched sod roofs, a traditional feature of many Scandinavian buildings, tend to be of a simpler design than flat green roofs. This is because the pitch of the roof reduces the risk of water penetrating through the roof structure, allowing the use of fewer waterproofing and drainage layers. Costs A properly designed and installed green roof system can cost 5 to 10 dollars per square foot. In Europe a well-designed and professionally installed fully integrated green roof can cost anywhere between 100 to 200 euros per square meter. The cost depends on what kind of roof it is, the structure of the building, and what plants can grow on the material that is on top of the roof. In the Spring 2007 issue of the Green Roof Infrastructure Monitor (Green Roofs for Healthy Cities web site), Jörg Breuning reflects the wind and fire loads of green roofs and how German insurance companies handle extensive green roofs. Some cost can also be attributed to maintenance. Extensive green roofs have low maintenance requirements but they are generally not maintenance free. German research has quantified the need to remove unwanted seedlings to approximately 0,1 min/(m²*year). Maintenance of green roofs often includes fertilization to increase flowering and succulent plant cover. If aesthetics is not an issue, fertilization and maintenance is generally not needed. Extensive green roofs should only be fertilized with controlled release fertilizers in order to avoid pollution of the storm water. Conventional fertilizers should never be used on extensive vegetated roofs. German studies have approximated the nutrient requirement of vegetated roofs to 5gN/m². It is also important to use a substrate that does not contain too much available nutrients. The FLL-guidelines specify maximum allowable nutrient content of substrates. http://www.outerspacesinc.com/landscapes_swimming_pools_outdoor_living_spaces_main_014.htm Mon, 15 Mar 2010 20:05:01 GMT Robert Nonemaker http://www.outerspacesinc.com/landscapes_swimming_pools_outdoor_living_spaces_main_014.htm#1