The following table shows some of the pros and cons of some potential green roof vegetation installation techniques. It has areas of deep and shallow substrate and is designed for a dead load of 300kg/m 2 and a live load of 300kg/m 2 on the decking and walkway mesh areas, and 150kg/m 2 on the planting area. Maintains the primary contractual relationship with both the prime design professional and general contractor. A down side to placing duct work within a conditioned attic – effectively insulating roof slope plane and endwall triangles. “A combination of organic and inorganic matter than anchors plant roots, drains water from the roof, and sustains plant growth.” ([[References for green roofs|Green Roofs for Healthy Cities and the Cardinal Group, 2006) Growing medium characteristics that affect stormwater performance include the following. Green roof shall have a Rational runoff coefficient of "x", for storms with durations of X hours and return frequency of X years. Determines occupancy requirement for fire codes. Poor design can lead to structural failure of a green roof. While not all extensive green roofs require permanent irrigation, almost all green roofs require irrigation during the establishment period (unless adequate rainfall occurs), often several times a day. Specialists retained to design irrigation. Water holding capacity affects how much water the growing medium can hold. Green roofs with a diverse plant palette are usually more resilient than those with very few species and also generally provide greater stormwater and other ecological benefits. Vegetated roofs generally also include vegetation free zones, for example, in areas prone to high wind uplift, where firebreaks are needed, for protection in areas where icicles are likely to fall, for easier access to roof flashings, or for other maintenance related issues. The following components are part of almost all green roofs. criteria presented by LEED, Sustainable Sites Initiative, Passive House, Living Building Challenge, etc. Choice of technique used to install green roof vegetation will depend on. runoff harvested from impervious surfaces, water harvested from air conditioning effluent, grey water harvested from baths, showers, and sinks. These steps are explained in greater detail below. For an excellent Test for leak before the warranty expires, to ensure the waterproofing membrane is sound just before the warranty expires. 1607.12.1 Distribution of roof loads. The load increases with the use of heavier roofing material. Minimum system dead load of ___psf (pounds per square foot) (determined according to ASTM E 2397 – 05 and E 2399 – 05). climate and microclimate (sun and wind exposure, precipitation, proximity to and reflection from glass curtain walls); type and condition of existing waterproofing, deck, and parapet if retrofit; building HVAC systems, including nature of intakes and exhausts onto the roof surface and presence of ondensate releases; potential impacts on vegetation; impact on potential building heating and cooling energy savings; water storage and supply (spigot and tap availability); opportunities for rainwater harvesting and storage; source of power if needed for irrigation or installation; elevations of existing or planned parapets, door thresholds, sills of curtain walls; building code and insurance requirements; and. I have found plenty of tables for adding these values but all of the span tables only specify dead loads of 10-20 PSF and live loads of up to 48 PSF. Green Roofs in Sustainable Landscape Design. The weight of all landscaping materials shall be considered as dead load and shall be computed on the basis of saturation of the soil as determined in accordance with Section 3.1.4 of ASCE 7. Green Roof Considerations. In addition to the information provided on this page, we recommend the following references, which address green roof design. Typically a water holding fabric or a plastic sheet with cup-like depressions, the water retention layer holds water for later use by plants. If winter aesthetics are of concern, be sure to include some species with winter interest. While green roofs are designed to retain and detain stormwater and supply vegetation with the water they need, drainage components are also needed to remove excess water. The ANSI/SPRI VF-1 External Fire Design Standard for Vegetative Roofs provides guidance for minimizing the risk of fire on green roofs, including recommendations for location and width of vegetation free zones for fire safety. The Importance of preserving an option for post-construction leak surveys will, however, influence the green roof design. Getter et al. Wind or surface runoff erosion protection, Amenities: for example, walkways, gathering areas, site furniture, water features, lighting, interpretive materials, other structural elements such as trellises and arbors. © 2020 by Minnesota Pollution Control Agency
foot) •Ceiling Construction –Gypsum (Sheetrock) finish ~ 10psf •Floor Construction –Carpet or Vinyl ~ 10 psf –Hardwood Floor ~ 12 psf –Ceramic Tile ~ 15 psf As a Intensive green roofs almost always need a permanent irrigation system, depending on factors such as project goals and plant palette. 2004. Structural steel offers much less of a dead load and provides superior support for live loads in multi-story buildings. controllers are available that time irrigation based on weather forecast and predicted evaporation rates, e.g. Comparison of most common extensive green roof planting methods Where uniform roof live loads are reduced to less than 20 psf (0.96 kN/m2) in accordance with Section 1607.12.2.1 and are applied to the design of structural members arranged so as to create continulty, the reduced roof live load shall be applied to adjacent spans or to alternate spans, whichever produces Ensuring that installation is carried out in accordance with local standards and incentive program performance requirements (if available). Landscape Architects are responsible for the design of the natural environment similar to the way architects are responsible for the design of a building or structure. For example, Philadelphia businesses can apply for a Green Roof Tax Credit that will provide a rebate for 25 percent of green roof costs up to $100,000. Examples of performance goals are listed below. Link to this table. Civil engineers work closely with architects and landscape architects to design and oversee site utilities including, storm drainage, sewer, electric, water, gas and communications supply. soil does not necessarily occupy the full depth of the assembly. Percent fines affects how quickly water moves through the growing medium. Gridirons over stages shall be designed to support a uniformly distributed live load of fifty psf in addition to the rigging loads indicated. dead load. My dead loads will be closer to 25 PSF for 2" of concrete if I used 150 lb/cu. Plants exposed to seasonal moisture variations may be more resilient. 2006. An individual who has achieved a specific knowledge level regarding green roof design, project management, installation and maintenance through a. 0.9D + 1.0E effect, or 0.9 when resisting the load when permanent. Here, each square foot of roof system delivers 50 pounds of live load and 15 pounds of dead load (65 psf total) to the structural support system. Maximum system dead load of ___psf (determined according to ASTM E 2397 – 05 and E 2399 – 05). Planting Green Roofs and Living Walls. The University of Melbourne’s demonstration green roof is designed for use by visitors and staff. For example: 2007; Van Woert et al., 2005). Refine project design, installation and maintenance, and lifecycle costs, based on green roof plan, specifications, and details. Examples include the following. While a simple manual overhead system is less expensive, drip systems are typically more water efficient than overhead systems and provide more uniform coverage. In some instances, it is possible to strengthen an existing roof in strategic areas (and not across the whole roof) in order to achieve the design outcome while also minimising costs. Testing right after waterproofing is installed allows for correction of any leaks prior to installing the green roof. Snodgrass. Advantages of not irrigating extensive green roofs include the following. Examples of optional green roof components are listed below. It has areas of deep and shallow substrate and is designed for a dead load of 300kg/m2 and a live load of 300kg/m2 on the decking and walkway mesh areas, and 150kg/m2 on the planting area. was redesigned to accommodate the additional dead loads associated with the green roof. Structural engineers determine the loading requirements of a roof to resist live loads, forces such as snow, rainwater, rooftop equipment, green roofs, and maintenance crews, as well as dead loads, the basic roofing structure and materials. Check when there is evidence of a leak that needs to be located. The growing and drainage media for the intensive beds and planters was also provided by SkyGarden. Even green roofs with underground drip irrigation systems will need overhead watering until the roots have grown enough to reach water from the irrigation driplines. The German FLL standards, which are widely accepted in the US, recommend that green roofs should not be installed on slopes steeper than 40 degrees. Assemble a team to fit project budget and goals and level of complexity. The weight of saturated plants and substrate must also be included in the load assessment. Descriptions of these techniques are provided in ASTM Standard Methods D6747 and D7007. stormwater, wildlife, aesthetics, food production; building code and insurance requirements, where applicable; how soon full vegetation cover is desired; maintenance labor, accessibility, and budget. Because many different green roof systems are often available that meet project goals, performance specifications (insert hyperlink to definition) can often result in more competitive pricing than descriptive specifications (insert hyperlink to definition), since performance specifications allow for more systems to meet the specifications than descriptive specifications. Green Roof Infrastructure: Design and Installation 201. Consequently, Sedum-based extensive profiles may qualify as ‘fire breaks’ on otherwise intensive green roof projects. ... 1.5 psf dead loads. lusher vegetation and moister soils provide greater evapotranspiration; sustainable use of stormwater harvested from hard surfaces, where harvested water is available; aesthetics: plants look greener more of the time; and. ft. when used for storage only) Dead load of attic floor, not floored = 10 lbs. • Floor live load = 40 psf • Floor dead load = 20 psf During construction, a 20-piece stack of 5/8 in. T&G plywood and per sq. Construction observation and administration. Acts as Project Manager responsible for coordination of the design team. Including self-sowing plant species in the plant palette similarly increases resilience. This section provides a discussion of issues to consider in green roof design. Some techniques that can be used to protect soil from eroding include erosion control blanket, mats, or soil tackifier.Care must be taken not to damage waterproofing membrane when securing erosion control fabric. Kits for All Purpose Buildings. Reviews the distribution of material and equipment during construction. The following table shows roles of various players that can be involved in green roof design and construction. Currently available guidelines, with the exception of the FLL Green Roofing Guideline, are based on very limited field data. The low voltage method is a survey technique that can be applied to green roof that are designed to enable this approach. Individuals passing the accreditation program requirements is trained in the following areas and therefore has a comprehensive understanding of all aspects of green roofs. Reviews plans for material transportation to roof. Ballast Pavers • Standard Ballast Thickness: 1 13/16 • Weight: 23 lbs/sf • Range of Standard Ballast Paver sizes available Paper work associated with the green roof (grants, review of shop drawings, permits, etc). Project budget will be crucial to inform project feasibility and design. stormwater retention calculations and estimates, noise reduction estimates, and roofing details). Each of these is discussed in greater detail below. This protection layer is a water-permeable, synthetic fiber material with good puncture resistance. grants, review of shop drawings, and permits). Depending on the project, additional roles not shown in the table may be needed. Weight loadings are therefore likely to be an underestimate. May conduct site analysis to reduce or eliminate internal drains. Creates drawings for the location and placement of penetrations and mechanical equipment on the roof deck. A landscape architect is a person licensed in the art of planning, designing and management of the built or natural environment. An individual or company (i.e. Guidelines for locations and widths are also included in the FLL Green Roofing Guideline. So analyzing the loading along one beam support a three-foot width of decking found 498 pounds per linear foot dead load and 348 pounds per linear foot live load totaling 446 pounds per linear foot. Provides electricity needed on the green roof for irrigation as well as anything else that required electricity on the roof. Source: Jakob Rope Systems. The uniform design live load in unoccupied landscaped areas on roofs shall be 20 psf (0.958 kN/m 2). In summary, intensive green roofs typically have slightly higher stormwater volume benefits, but also have higher installation and maintenance costs and require more structural capacity compared to semi-intensive and extensive green roofs. Review of proposed design to ensure that it meets municipal requirements. A root barrier prevents plant roots from damaging the waterproofing membrane. Green roof products shall be fully compatible with the waterproofing system and shall be installed in a manner that does not negatively impact waterproofing assembly in any way. For projects where stormwater goals for volume or pollutant reduction are the primary driver of roof size, use Minimal Impact Design Standards (MIDS) or other credits calculator to determine green roof size needed to meet the goals. 2006. When using waterproofing membranes that are root resistant, such as, for example, PVC, TPO and EPDM membranes, a separate root barrier may not be needed. A typical value for the roofing material itself is 10 PSF. An engineered slope stability analysis should be performed for green roofs with slopes above 2:12 (10 degrees). Low voltage and TDR methods rely on the facts that: 1) the waterproofing membrane is an electrical insulator, and 2) water is an electrically conductive medium. Leak detection of green roof assemblies that incorporate root-barriers is very challenging, if not impossible in most instances. Permeability affects how quickly water moves through the growing medium. For those designing the vegetated roof, the extra dead load of mineral fiber can increase costs for structural elements overall in the roof, the walls or columns supporting it, and the foundation. Design and construction observation of irrigation systems. Two examples from the literature are summarized below. An architect is a person licensed in the art of planning, designing and overseeing the construction of buildings. A combination of techniques can be used to combine benefits of several techniques as well as to maximize vegetation resilience. Once a roof is fully covered with vegetation, the vegetation typically protects soil from erosion. sun and wind exposure, precipitation, proximity to and exposure associated with glass curtain walls); project goals: e.g. There are a number of things to consider when designing for a green roof. Damage to a wall can arise from wind forces, plant load, cable tension, and human access. (FLL) Richlinien für die Planung, Ausführung and Plege von Dachbegrünung (Guideline for the Planning, Construction and Maintenance of Green Roof –Green Roofing Guideline: developed by the German Research Society for Landscape Development and Landscape Design), latest English Edition. Because green roof technology is new to the North American market, city officials may not be familiar with the systems requirements and considerations. 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