Vegetative roofs may provide significant cooling savings in the summer and some heating savings in the winter. If you want to do the water evaporation thing, you probably could do as good a job by sprinkling the top of a white reflective roof. Stone ballast or pavers are also used around roof access and rooftop equipment. (Example: Localize burning of plants has been documented as late as September in New England.). Leak detection should always be performed prior to the installation of protection boards and non-conductive root barriers to allow more precise location of leaks. al., 2009, Environment Science & Technology Vol. As a result, white EPDM may be difficult to test, as well as black EPDM. These systems are typically placed above the waterproofing and are designed to accommodate movement of water through the vegetative roof components. A capillary break immediately above the membrane is required for most membranes. ICC also provides standards for parapet heights and requirements for railings. Calculations are required to prove that the ballast is adequate in preventing uplift on a project-by-project basis. By reducing both the volume and the rate of storm water runoff, vegetative roofs benefit cities with combined sewer overflow (CSO) impacts. Comply with applicable code requirements for loading criteria, typically ASCE 7 and ANSI/SPRI RP-14 Wind Design Standard for Vegetative Roofing Systems. Engineered growing medium based on minerals and organic material. Disclaimer, Unified Facilities Guide Specifications (UFGS), Center for Green Roof Research, Penn State University, Standard Guide for Selection of Membranes Used in Vegetative Roofing Systems, National Roofing Contractors Association (NRCA), Forschungsgesellschaft Landschaftentwicklung Landschaftsbau. Copper hydroxide root barriers are banned in several European countries and Canada. "Structural Considerations for Green Roof Retrofits," technical memorandum prepared by Magnusson Klemencic Associates, Inc. for City of Seattle Public Utilities department, 2007. If designed specifically to increase the biodiversity and attract a particular fauna and flora, they are called Biodiverse Green Roofs. In addition, ASTM International (ASTM), through the Green Roof Task Group E06.71, is in the process of developing guidelines and testing procedures specifically for vegetative roof products. Due diligence is highly recommended. These systems are fully bonded to the deck. Where possible, the designer should consider the use of a single manufacturer for the interfacing systems. Check with your local code official regarding the local code requirements for vegetative roofs. Hence, they do not allow an extensive vegetative roof in this configuration, because an extensive vegetative roof is less than 6 inches thick, by definition. All seams in insulation layers should be staggered from the layers above and below by a minimum of 6 inches. However, elements such as roof drains may need to be inspected and tested separately because they must be isolated from the electric leak detection process. This causes the soil to dry out faster, causing more plants replacement. Because the few North American roofs that have been built to date demonstrate such a wide variety of settings and approaches, it is impossible to highlight "representative" case studies here. Green Roofs offer additional space for numerous uses. The mats incorporate a fiber, fabric or mesh reinforcing layer which prevents them from disintegrating during shipping and handling. Suitable plants include various Sedum species, herbs and some grasses. Steeper slope (up to 4%) may help with drainage and may help reduce ponding, which could be desirable for wood or light steel framed systems susceptible to excessive deflection. flashings and penetrations) may become the most important factor in determining the longevity of an installation. Existing roof substrates must be inspected for leaks. Consequently, consideration should be given to providing protection for all surfaces of the roofing/waterproofing system. The survival rate is generally better when starting with plugs than with larger plants (e.g., quart- or gallon-sized plants). These include the Earth Pledge Foundation in New York City, Northwest Eco Building Guild, Green Roof Advisory Group (GRAG) in Austin, TX, Green Roof info Think-Tank (GRiT) in Portland, Ore. and Sustainable ClevelandGreen Building Coalition. 43, No. 4 DOI: 10.1007/s11252-008-0069-4. In cities with combined storm and wastewater sewer systems, storm water dilutes the sanitary waste water, rendering treatment less efficient. There are studies that support the energy conservation aspects of vegetative roofs. Unlike white roofs, which tend to lose the ability to reduce temperature as they age, vegetative roofs continue to have the ability to mitigate the heat island effect. Vegetative roof covers are particularly effective at controlling runoff on the large roofs typical of commercial and institutional buildings because typically a greater portion of these roofs can be vegetative than on other building types. Accomodates a variety of vegetation based on climate, landscape design, load bearing requirements and desired benefits to building owners and communities. Examples are hydro-mulch, plant fiber blankets, and photo-degradable netting. General Overview of Green Roof types Green Roof Technology. In general, warranties insure the owner against defective products and/or inadequate installation by the contractor. Construction oversight must find constructed leaks. Fabric should also be used to protect flashing membranes from direct contact with media at perimeters and penetrations. Green roofs provide important natural habitats for flora and fauna. They retain various amounts of water, based on their design and thickness ranging from 0.06 gal/ft to 0.16 gal/ft. The bottom line on energy might be summed up by this quote from Joe Lstiburek in footnote 3 to his Building Science Insight 052, "Seeing Red Over Green Roofs:" "The assumptions are pretty important. That being said, it is essential to provide hose bibs where an irrigation system has not been used in case irrigation should become necessary. The materials should be resistant to UV (although they do tend to become rapidly concealed by soil and plants). High Voltage (HV) Testing: HV testing may take less time to perform compared to LV testing. National Institute of Building Sciences Consideration of appropriate design loads is the responsibility of the project engineer and should be addressed before the vegetative roof system is designed.". In 2009 APEX Green Roof began maintaining the roof. Seattle, Portland, and Philadelphia, to name a few) advocate for a combination of LID practices including vegetative roofs, rainwater harvesting, permeable paving, and bio-retention "rain gardens" to mitigate site impacts on water resources while creating "vegetative storm water infrastructure". 3 inches of lightweight green roof media, unirrigated. Tests must be run and baseline readings taken to calibrate the equipment to prevent damage. How can runoff volume be reduced? In Arizona, where there is the most benefit of cooling, it is like stealing from one bucket to pay for another. To provide a vigorous multi-seasonal ground cover and to minimize problems associated with disease, insects, or climatic stresses, it is best to avoid large drifts of a single species. A properly adjusted irrigation system (by experienced installers) will almost always be more efficient than hand watering technique, if hand water is ever done. Their use is limited to very controlled applications, due to the increased need for maintenance. Conventional 'beehive' or 'bonnet' strainers are not suitable for this purpose. Figure 5. These include Allium, Chrysanthemum, Talinum, Dianthus, Achillea, and Phlox, as well as many grass varieties. As noted ASTM D8014 Standard Guide for Selection of Membranes Used in Vegetative Roofing Systems, "vegetative roof systems can be adversely affected by either excessive or insufficient drainage capacity. In every project case, both from the client's expectation, regional location and site-specific issues should be considered when talking about irrigation and it potential implementation. Electric leak detection can precisely locate the source of leaks below the planting system. Many jurisdictions (i.e. Reflected sunlight may burn localized areas. Roofing by Sika Sarnafil. On the other hand, the additional cost, possible water usage to irrigate the plants, and required ongoing maintenance may make them less appropriate. Although modern vegetative roof systems have not yet been in place longer than 40 years, many researchers expect that these installations will last 50 years and longer before they require significant repair or replacement. Perennial Garden is the ideal green roof system build-up for growing a wide variety of blooming perennials, aromatic shrubs and ornamental grasses. al., 2008, Urban Ecosystems Vol. The green roofing system Rockery Type Plants leads to an extensive green roof with sophisticated design and individual character. Vegetative roofs have important acoustical benefits, especially for higher frequency sounds. But they do not include plant recommendations. Some retrofit applications, however, can result in non-trivial savings of both air-conditioning and heating. The challenge in designing extensive vegetative roofs is to replicate many of the benefits of vegetative open space, while keeping them light and affordable. Although its principles apply to vegetative roofs in the United States, its specific recommendations apply to a central European climate. The growing media should be a well-drained engineered mineral soil and must be carefully designed for grain-size distribution, void ratio, moisture retention, etc. Vegetative roofs can be designed in conjunction with solar panels, and also work very well in combination with other 'low-impact' development measures, such as infiltration beds, rain gardens, bio-retention systems, cisterns and rain barrels. A standing water test can be conducted by plugging the drains and creating dams to contain water to a depth of 2" minimum at the high point for 2448 hours. rain gardens, bio-swales, etc., it will almost always be more economical than a vegetative roof. A conductive wire loop is laid out on the membrane around a section of the area to be tested. A minimum initial planting density, in most cases, will be two plugs per square foot. AMCOL International Building, Hoffman Estates, IL. Vegetative roofs are divided into two categories: 1) extensive vegetative roofs, which are 6 inches or shallower and are frequently designed to satisfy specific engineering and performance goals, and 2) intensive vegetative roofs, which may become quite deep and merge into more familiar on-structure plaza landscapes with promenades, lawn, large perennial plants, and trees. Note that as of this writing a conventional configuration is required by some insurance underwriters. Additionally, ZinCo has designed a range of fantastic hybrid solutions and elaborate system build-ups focusing on stormwater management and counteracting Urban Heat Island effects. Baltimore, MD 21211. Forty years of German experience and research indicates that extensive vegetative roofs will succeed in most climates, if properly designed. Green roofs save energy compared to uninsulated roofs or poorly insulated roofs or even better, black poorly insulated roofs. The "ideal" balance between a swift release of excess water, which is beneficial, and the risk of damage/degradation of certain materials, which is undesirable, should be sought. Uniform foliage cover should be achieved within 2 years in most cases. If a vapor retarder is part of the roof system, it may limit the effective use of low voltage testing. The sewer pipes can be reduced in capacity. 43,000 square feet. Fit with other sustainable systems or renewable technologies, such as solar panels, or "cool" (reflective) roof systems. Standard landscaping work considers plant hardiness; tolerance for sun and shade; and preference for wet, dry, rich, poor, alkaline, or acid soils as the major concerns to influence plant selection. Sedum-only extensive green roofs require 50-80% more maintenance than a divers extensive greening with natural vegetation dynamic. In mild weather and with the assistance of temporary irrigation, Sedum cuttings can be relied on to generate a uniform ground cover. If the project is insured under FM Global, then also comply with FM Data Sheet 1-28. Because of the shallow profile, extensive Green Roofs also add less weight to a structure than deeper system. Provide for proper waterproofing terminations and counterflashing at or (preferably) above grade, either lapped into through-wall flashing at the backup wall or (where this is not possible) tucked into flashed reglets at the face as required by the specific material supplier/manufacture. Modules may be established at the nursery using the direct seeding or plug installation method. Because of the relative isolation of vegetative roofs and their often exposed environments, these roofs should not be looked to as a replacement for lost native habitat. One must take into consideration, however, the added cost of vegetative roofs. Rubber, polyethylene and expanded polystyrene rigid foam are used in the production of drainage elements. 2.2.3.2.2). Finally, is the quality of construction the same? The question is, where does the water come from? After establishment of the vegetation, the maintenance is limited to one or two inspections a year. Waterproofing materials cannot withstand decades of root and biological attack unaided. An Extensive Green Roof represents a natural form of vegetation that is largely self-sustaining and evolving. On a roof that is too flat, inadequate drainage can lead to damage to the membrane and plants. In temperate climates temporary irrigation may not be necessary. Insects, spiders, snails, birds, and rodents (rats, mice, squirrels) all promote damage to the soil, plants, and roof materials, as well as create potential safety issues to maintenance personnel. Installed over Sarnafil PVC membrane. However, this instruction does not address the specificity of this type of vegetated roof environment.). In all instances, materials, methods of installation and quality assurance/quality control procedures must be more stringent when vegetative roof installation is involved. temperate climate zones with Gulf Stream influence, like northern Europe. Figure 2. (FLL) in Germany Guideline for the Planning, Execution and Upkeep of Green-Roof Sites (Richlinien fr die Planung, Ausfhrung and Plege von Dachbegrnung). These include spray testing, standing water flood testing, flowing water testing and the electric leak detection procedure.
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