(Created page with "==Glossary== *Ballast: A material used to hold loose laid roofing materials in place. (Green Roofs for Healthy Cities. No publication year given) *Built in place green roof: i...")
 
m
 
(11 intermediate revisions by the same user not shown)
Line 1: Line 1:
 +
NOTE: The numbered links go to Green Roofs for Healthy Cities main webpage.
 +
 
==Glossary==
 
==Glossary==
*Ballast: A material used to hold loose laid roofing materials in place. (Green Roofs for Healthy Cities. No publication year given)
+
*Ballast: A material used to hold loose laid roofing materials in place [http://www.greenroofs.org/]
*Built in place green roof: in a built-in-place green roof, the layers of the green roof are installed on-site, as opposed to green roof trays or mats, which are delivered pre-assembled
 
 
 
*Cation exchange capacity: The quantity of positive ions (cation) that can be absorbed by growing medium. (Green Roofs for Healthy Cities. No publication year given)
 
*Compaction: increase in growing medium density
 
 
 
*Curtain wall: A non-structural outer wall, often of glass or steel
 
*Dead load: All permanently placed materials on and below the roof (e ,g. green roof materials, green roof plants, ceiling fans) (Green Roofs for Healthy Cities. No publication year given).
 
*Descriptive Specifications: Require specific products and methods of installation. Compared to performance specifications, these give the designer the most control, but since they allow the contractor less flexibility and innovation, they can also be less cost effective.
 
*Drain access chamber: removable cover installed around roof drains to protect the drains from clogging while still allowing for easy access to the drains (See Figure 5.8).
 
*Drainage layer: Drainage layers, such as, for example, drainage aggregate, drainage sheets, and drainage mats, convey water across the roof surface under the growing medium and filter fabric, and are available in a range of different materials and drainage capacities The drainage layer must be selected to drain well enough so as to not compromise underlying waterproofing or building, but also retain water in a manner that meets stormwater management and vegetation goals. The choice of the drainage layer will have a significant impact on the peak rate and time delay of discharges from the green roof (Taylor and Gangnes, 2007). (link to description in 5E, Images 5.3 and 5.7)
 
 
 
*Leak detection system: Leak detection systems allow for detecting and pinpointing the exact location of leaks in the waterproof membrane. (link to description in 5E, image 5.15)
 
 
 
*Erosion protection layer: erosion control blanket, netting, or tackifier adequate to protect green roof from wind and water erosion.
 
 
 
*Evapotranpiration: water conveyed to the atmosphere through evaporation and plant transpiration.
 
 
 
*Extensive green roof: an extensive green roof has growing medium that is 6” or less deep (see Table 5.2)
 
 
 
*Filter fabric: a lightweight, rot-proof material laid over or included as part of a drainage layer to keep the growing medium in place and thereby prevent fine particles from blocking the drainage system.” (Green Roofs for Healthy Cities. No publication year given). Link to Image 5.3
 
 
 
*Flashing: the weatherproof material installed between roof sheathing (or wall sheathing) and the finish materials to help keep moisture away from the sheathing (Green Roofs for Healthy Cities. No publication year given).
 
 
 
*Growing medium: the particulate matter or substrate that anchors the plant roots to sustain the plant growth (Green Roofs for Healthy Cities. No publication year given).
 
 
 
*Intensive green roof: an intensive green roof has growing medium that is more than 6” deep (see Table 5.2)
 
*Irrigation system: Systems which deliver moisture to the growing medium making it available for plant use. (Green Roofs for Healthy Cities. No publication year given) (link to description in 5E, image 5.16)
 
 
 
*Lifecycle cost: The capital and operational cost of a construction item or system during the estimated useful life of the building (Green Roofs for Healthy Cities. No publication year given)
 
 
 
*Live load: All equipment and people on the roof. They are not permanent elements. (Green Roofs for Healthy Cities. No publication year given)
 
 
 
*Maximum media density: the density of a mixed media material determined after it has been subjected to a specific amount of compaction and hydrated by immersion to simulate prolonged exposure to both foot traffic and rainfall (ASTM E 2399-05)
 
 
 
*Maximum Media Water Retention (MMWR): terminology used in ASTM E 2399-05 for FLL Maximum Water Capacity (MWC); the quantity of water held in a media at the maximum media density. This is a useful measure of the capacity of a media to hold water under drained conditions.
 
*Maximum Water Capacity (MWC): terminology used in FLL guidelines for Maximum Media Water Retention (MMWR); the quantity of water held in a media at the maximum media density. This is a useful measure of the capacity of a media to hold water under drained conditions.
 
 
 
*Membrane protection layer: A material used to protect the waterproofing membrane and/or insulation layer during the installation of a green roof.”(Green Roofs for Healthy Cities. No publication year given)
 
 
 
*Modular green roof: A green roof system which combines one or more layers in a single pre-manufactured product (e.g. drainage, growing medium, and plants). (adapted from Green Roofs for Healthy Cities. No publication year given)
 
 
 
*Performance Specifications: allow the contractor to choose what products to install and how to install them as long as specified performance goals are met. Performance specifications allow the contractor more flexibility and innovation compared to descriptive specifications, and therefore often result in more economical bids.
 
 
 
*Pre-grown mats: Mats filled with growing medium and delivered to the site pre-grown with green roof vegetation, typically Sedums. Pre-grown mats are delivered in rolls like sod. The mats can be biodegradable or permanent (link to description in 5E, images 5.13 and 5.14)
 
*R factor: The measure of thermal resistance. R = K·m²/ (adapted from Green Roofs for Healthy Cities. No publication year given).
 
 
 
*Root barrier: green roof component that prevents plant roots from damaging the waterproofing membrane. (link to description in 5E)
 
 
 
*Water Permeability: the coefficient, which when multiplied by the hydraulic gradient will yield the apparent velocity with which water, at 68°F (20°C) will move through a cross-section of media. The conditions created in this method apply to freely-drained media where the free water surface is level with the upper surface of the media layer (such as, impending accumulation of water above the surface of the media).
 
 
 
*Water retention layer: Typically a water holding fabric or a plastic sheet with cup-like depressions, the water retention layer holds water for later use by plants.
 
 
 
*Wind uplift: a net upward force that occurs when the pressure below a roof is greater than above it.
 
 
 
==References==
 
 
 
*Berghage, R. Penn State Center for Green Roof Research. Green Roof Media Nutrient Testing, Nutrient Management, and Runoff Water Quality. Presentation to NASA Workshop.
 
*Cantor, S. L. 2008. Green Roofs in Sustainable Landscape Design. W.W.Norton, NY.
 
*Forschungsgesellschaft Landschaftsentwicklung Landschaftsbau e.V. (FLL) Richlinien für die Planung, Ausführung and Plege von Dachbegrünung (Guideline for the Planning, Execution and Upkeep of Green-Roof Sites: developed by the German Research Society for Landscape Development and Landscape Design)
 
*Green Roofs for Healthy Cities and The Cardinal Group. 2006. Green Roof Design 101: Introductory Course. Second Edition Participant’s Manual.
 
*Green Roofs for Healthy Cities. No publication year given. Green Roof Infrastructure: Design and Installation 201.
 
*National Institute of Building Sciences. Whole Building Design Guide available at http://www.wbdg.org on 12/10/2012
 
*Snodgrass, E.C., and L.L. Snodgrass. 2006. Green Roof Plants. Timber Press, Portland OR.
 
*Taylor, B. L. and Gangnes, D. 2007. Technical Memorandum: Stormwater Control Potential for Seattle Green Roof Retrofits’ Seattle Public Utilities Green Roof Retrofit Study.
 
 
 
 
*Built in place green roof: in a built-in-place green roof, the layers of the green roof are installed on-site, as opposed to green roof trays or mats, which are delivered pre-assembled
 
*Built in place green roof: in a built-in-place green roof, the layers of the green roof are installed on-site, as opposed to green roof trays or mats, which are delivered pre-assembled
 
+
*Cation exchange capacity: The quantity of positive ions (cation) that can be absorbed by growing medium. [http://www.greenroofs.org/]
 
 
*Cation exchange capacity: The quantity of positive ions (cation) that can be absorbed by growing medium. (Green Roofs for Healthy Cities. No publication year given)
 
 
*Compaction: increase in growing medium density
 
*Compaction: increase in growing medium density
 
 
 
*Curtain wall: A non-structural outer wall, often of glass or steel
 
*Curtain wall: A non-structural outer wall, often of glass or steel
*Dead load: All permanently placed materials on and below the roof (e ,g. green roof materials, green roof plants, ceiling fans) (Green Roofs for Healthy Cities. No publication year given).
+
*Dead load: All permanently placed materials on and below the roof (e ,g. green roof materials, green roof plants, ceiling fans) [http://www.greenroofs.org/]
 
*Descriptive Specifications: Require specific products and methods of installation. Compared to performance specifications, these give the designer the most control, but since they allow the contractor less flexibility and innovation, they can also be less cost effective.
 
*Descriptive Specifications: Require specific products and methods of installation. Compared to performance specifications, these give the designer the most control, but since they allow the contractor less flexibility and innovation, they can also be less cost effective.
*Drain access chamber: removable cover installed around roof drains to protect the drains from clogging while still allowing for easy access to the drains (See Figure 5.8).
+
*[http://stormwater.pca.state.mn.us/index.php/File:Drain_Access_Chambers_at_Phillips_Eco-Enterprise_Green_Roof,_Minneapolis,_MN.jpg Drain access chamber]: removable cover installed around roof drains to protect the drains from clogging while still allowing for easy access to the drains
*Drainage layer: Drainage layers, such as, for example, drainage aggregate, drainage sheets, and drainage mats, convey water across the roof surface under the growing medium and filter fabric, and are available in a range of different materials and drainage capacities The drainage layer must be selected to drain well enough so as to not compromise underlying waterproofing or building, but also retain water in a manner that meets stormwater management and vegetation goals. The choice of the drainage layer will have a significant impact on the peak rate and time delay of discharges from the green roof (Taylor and Gangnes, 2007). (link to description in 5E, Images 5.3 and 5.7)
+
*[http://stormwater.pca.state.mn.us/index.php/File:Aggregate_Drainage_Layer.jpg Drainage layer]: Drainage layers, such as, for example, drainage aggregate, drainage sheets, and drainage mats, convey water across the roof surface under the growing medium and filter fabric, and are available in a range of different materials and drainage capacities The drainage layer must be selected to drain well enough so as to not compromise underlying waterproofing or building, but also retain water in a manner that meets stormwater management and vegetation goals. The choice of the drainage layer will have a significant impact on the peak rate and time delay of discharges from the green roof ([[References for green roofs|Taylor and Gangnes, 2007]])
 
 
 
 
*Leak detection system: Leak detection systems allow for detecting and pinpointing the exact location of leaks in the waterproof membrane. (link to description in 5E, image 5.15)
 
 
 
 
 
 
*Erosion protection layer: erosion control blanket, netting, or tackifier adequate to protect green roof from wind and water erosion.
 
*Erosion protection layer: erosion control blanket, netting, or tackifier adequate to protect green roof from wind and water erosion.
 
+
*Evapotranspiration: water conveyed to the atmosphere through evaporation and plant transpiration.
 
+
*[http://stormwater.pca.state.mn.us/index.php/Types_of_green_roofs Extensive green roof]: an extensive green roof has growing medium that is 6 inches or less deep
*Evapotranpiration: water conveyed to the atmosphere through evaporation and plant transpiration.
+
*[http://stormwater.pca.state.mn.us/index.php/File:Typical_green_roof_sections_2.jpg Filter fabric]: a lightweight, rot-proof material laid over or included as part of a drainage layer to keep the growing medium in place and thereby prevent fine particles from blocking the drainage system. [http://www.greenroofs.org/]
 
+
*Flashing: the weatherproof material installed between roof sheathing (or wall sheathing) and the finish materials to help keep moisture away from the sheathing [http://www.greenroofs.org/]
 
+
*Growing medium: the particulate matter or substrate that anchors the plant roots to sustain the plant growth [http://www.greenroofs.org/]
*Extensive green roof: an extensive green roof has growing medium that is 6” or less deep (see Table 5.2)
+
*[http://stormwater.pca.state.mn.us/index.php/Types_of_green_roofs Intensive green roof]: an intensive green roof has growing medium that is more than 6 inches deep
 
+
*[http://stormwater.pca.state.mn.us/index.php/File:Irrigation_Installation_at_Minneapolis_Central_Library_Green_Roof,_Minneapolis,_MN.jpg Irrigation system]: Systems which deliver moisture to the growing medium making it available for plant use [http://www.greenroofs.org/]
 
+
*[http://stormwater.pca.state.mn.us/index.php/File:Electronic_Leak_Detection_at_Target_Center_Green_Roof,_Minneapolis,_MN.jpg Leak detection system]: Leak detection systems allow for detecting and pinpointing the exact location of leaks in the waterproof membrane
*Filter fabric: a lightweight, rot-proof material laid over or included as part of a drainage layer to keep the growing medium in place and thereby prevent fine particles from blocking the drainage system.” (Green Roofs for Healthy Cities. No publication year given). Link to Image 5.3
+
*Lifecycle cost: The capital and operational cost of a construction item or system during the estimated useful life of the building [http://www.greenroofs.org/]
 
+
*Live load: All equipment and people on the roof. They are not permanent elements [http://www.greenroofs.org/]
 
+
*Maximum media density: the density of a mixed media material determined after it has been subjected to a specific amount of compaction and hydrated by immersion to simulate prolonged exposure to both foot traffic and rainfall ([http://www.astm.org/ ASTM] E 2399-05)
*Flashing: the weatherproof material installed between roof sheathing (or wall sheathing) and the finish materials to help keep moisture away from the sheathing (Green Roofs for Healthy Cities. No publication year given).
 
 
 
 
 
*Growing medium: the particulate matter or substrate that anchors the plant roots to sustain the plant growth (Green Roofs for Healthy Cities. No publication year given).
 
 
 
 
 
*Intensive green roof: an intensive green roof has growing medium that is more than 6” deep (see Table 5.2)
 
 
 
*Irrigation system: Systems which deliver moisture to the growing medium making it available for plant use. (Green Roofs for Healthy Cities. No publication year given) (link to description in 5E, image 5.16)
 
 
 
 
 
*Lifecycle cost: The capital and operational cost of a construction item or system during the estimated useful life of the building (Green Roofs for Healthy Cities. No publication year given)
 
 
 
 
 
*Live load: All equipment and people on the roof. They are not permanent elements. (Green Roofs for Healthy Cities. No publication year given)
 
 
 
 
 
*Maximum media density: the density of a mixed media material determined after it has been subjected to a specific amount of compaction and hydrated by immersion to simulate prolonged exposure to both foot traffic and rainfall (ASTM E 2399-05)
 
 
 
 
 
 
*Maximum Media Water Retention (MMWR): terminology used in ASTM E 2399-05 for FLL Maximum Water Capacity (MWC); the quantity of water held in a media at the maximum media density. This is a useful measure of the capacity of a media to hold water under drained conditions.  
 
*Maximum Media Water Retention (MMWR): terminology used in ASTM E 2399-05 for FLL Maximum Water Capacity (MWC); the quantity of water held in a media at the maximum media density. This is a useful measure of the capacity of a media to hold water under drained conditions.  
 
*Maximum Water Capacity (MWC): terminology used in FLL guidelines for Maximum Media Water Retention (MMWR); the quantity of water held in a media at the maximum media density. This is a useful measure of the capacity of a media to hold water under drained conditions.
 
*Maximum Water Capacity (MWC): terminology used in FLL guidelines for Maximum Media Water Retention (MMWR); the quantity of water held in a media at the maximum media density. This is a useful measure of the capacity of a media to hold water under drained conditions.
 
+
*Membrane protection layer: A material used to protect the waterproofing membrane and/or insulation layer during the installation of a green roof [http://www.greenroofs.org/]
 
+
*Modular green roof: A green roof system which combines one or more layers in a single pre-manufactured product (e.g. drainage, growing medium, and plants) [http://www.greenroofs.org/]
*Membrane protection layer: A material used to protect the waterproofing membrane and/or insulation layer during the installation of a green roof.”(Green Roofs for Healthy Cities. No publication year given)
 
 
 
 
 
*Modular green roof: A green roof system which combines one or more layers in a single pre-manufactured product (e.g. drainage, growing medium, and plants). (adapted from Green Roofs for Healthy Cities. No publication year given)
 
 
 
 
 
 
*Performance Specifications: allow the contractor to choose what products to install and how to install them as long as specified performance goals are met. Performance specifications allow the contractor more flexibility and innovation compared to descriptive specifications, and therefore often result in more economical bids.
 
*Performance Specifications: allow the contractor to choose what products to install and how to install them as long as specified performance goals are met. Performance specifications allow the contractor more flexibility and innovation compared to descriptive specifications, and therefore often result in more economical bids.
 
+
*[http://stormwater.pca.state.mn.us/index.php/File:Installation_of_Pregrown_Sedum_Mat.jpg Pre-grown mats]: Mats filled with growing medium and delivered to the site pre-grown with green roof vegetation, typically Sedums. Pre-grown mats are delivered in rolls like sod. The mats can be biodegradable or permanent
 
+
*R factor: The measure of thermal resistance. R = K·m²/ [http://www.greenroofs.org/]
*Pre-grown mats: Mats filled with growing medium and delivered to the site pre-grown with green roof vegetation, typically Sedums. Pre-grown mats are delivered in rolls like sod. The mats can be biodegradable or permanent (link to description in 5E, images 5.13 and 5.14)
 
*R factor: The measure of thermal resistance. R = K·m²/ (adapted from Green Roofs for Healthy Cities. No publication year given).
 
 
 
 
 
 
*Root barrier: green roof component that prevents plant roots from damaging the waterproofing membrane. (link to description in 5E)
 
*Root barrier: green roof component that prevents plant roots from damaging the waterproofing membrane. (link to description in 5E)
 
 
 
*Water Permeability: the coefficient, which when multiplied by the hydraulic gradient will yield the apparent velocity with which water, at 68°F (20°C) will move through a cross-section of media. The conditions created in this method apply to freely-drained media where the free water surface is level with the upper surface of the media layer (such as, impending accumulation of water above the surface of the media).
 
*Water Permeability: the coefficient, which when multiplied by the hydraulic gradient will yield the apparent velocity with which water, at 68°F (20°C) will move through a cross-section of media. The conditions created in this method apply to freely-drained media where the free water surface is level with the upper surface of the media layer (such as, impending accumulation of water above the surface of the media).
 
 
 
*Water retention layer: Typically a water holding fabric or a plastic sheet with cup-like depressions, the water retention layer holds water for later use by plants.
 
*Water retention layer: Typically a water holding fabric or a plastic sheet with cup-like depressions, the water retention layer holds water for later use by plants.
 +
*Wind uplift: a net upward force that occurs when the pressure below a roof is greater than above it.
  
 +
<noinclude>==Related pages==
 +
*[[Green roofs]]
 +
*[[Overview for green roofs]]
 +
*[[Types of green roofs]]
 +
*[[Design criteria for green roofs]]
 +
*[[Construction specifications for green roofs]]
 +
<!--*[[Construction observations for green roofs]]-->
 +
*[[Assessing the performance of green roofs]]
 +
*[[Operation and maintenance of green roofs]]
 +
<!--*[[Calculating credits for green roofs]]-->
 +
*[[Cost-benefit considerations for green roofs]]
 +
*[[Plant lists for green roofs]]
 +
<!--*[[Additional considerations for green roofs]]-->
 +
*[[Case studies for green roofs]]
 +
*[[Links for green roofs]]
 +
*[[References for green roofs]]
 +
*[[Supporting material for green roofs]]
 +
*[[Green roofs terminology and glossary]]
 +
*[[Green roof fact sheet]]
 +
*[[Requirements, recommendations and information for using green roofs as a BMP in the MIDS calculator]]</noinclude>
  
*Wind uplift: a net upward force that occurs when the pressure below a roof is greater than above it.
+
<noinclude>[[Category:Level 3 - Best management practices/Structural practices/Green roof]]</noinclude>
 
 
 
 
==References==
 
 
 
 
 
*Berghage, R. Penn State Center for Green Roof Research. Green Roof Media Nutrient Testing, Nutrient Management, and Runoff Water Quality. Presentation to NASA Workshop.
 
*Cantor, S. L. 2008. Green Roofs in Sustainable Landscape Design. W.W.Norton, NY.
 
*Forschungsgesellschaft Landschaftsentwicklung Landschaftsbau e.V. (FLL) Richlinien für die Planung, Ausführung and Plege von Dachbegrünung (Guideline for the Planning, Execution and Upkeep of Green-Roof Sites: developed by the German Research Society for Landscape Development and Landscape Design)
 
*Green Roofs for Healthy Cities and The Cardinal Group. 2006. Green Roof Design 101: Introductory Course. Second Edition Participant’s Manual.
 
*Green Roofs for Healthy Cities. No publication year given. Green Roof Infrastructure: Design and Installation 201.
 
*National Institute of Building Sciences. Whole Building Design Guide available at http://www.wbdg.org on 12/10/2012
 
*Snodgrass, E.C., and L.L. Snodgrass. 2006. Green Roof Plants. Timber Press, Portland OR.
 
*Taylor, B. L. and Gangnes, D. 2007. Technical Memorandum: Stormwater Control Potential for Seattle Green Roof Retrofits’ Seattle Public Utilities Green Roof Retrofit Study.
 

Latest revision as of 14:41, 17 January 2023

NOTE: The numbered links go to Green Roofs for Healthy Cities main webpage.

Glossary

  • Ballast: A material used to hold loose laid roofing materials in place [1]
  • Built in place green roof: in a built-in-place green roof, the layers of the green roof are installed on-site, as opposed to green roof trays or mats, which are delivered pre-assembled
  • Cation exchange capacity: The quantity of positive ions (cation) that can be absorbed by growing medium. [2]
  • Compaction: increase in growing medium density
  • Curtain wall: A non-structural outer wall, often of glass or steel
  • Dead load: All permanently placed materials on and below the roof (e ,g. green roof materials, green roof plants, ceiling fans) [3]
  • Descriptive Specifications: Require specific products and methods of installation. Compared to performance specifications, these give the designer the most control, but since they allow the contractor less flexibility and innovation, they can also be less cost effective.
  • Drain access chamber: removable cover installed around roof drains to protect the drains from clogging while still allowing for easy access to the drains
  • Drainage layer: Drainage layers, such as, for example, drainage aggregate, drainage sheets, and drainage mats, convey water across the roof surface under the growing medium and filter fabric, and are available in a range of different materials and drainage capacities The drainage layer must be selected to drain well enough so as to not compromise underlying waterproofing or building, but also retain water in a manner that meets stormwater management and vegetation goals. The choice of the drainage layer will have a significant impact on the peak rate and time delay of discharges from the green roof (Taylor and Gangnes, 2007)
  • Erosion protection layer: erosion control blanket, netting, or tackifier adequate to protect green roof from wind and water erosion.
  • Evapotranspiration: water conveyed to the atmosphere through evaporation and plant transpiration.
  • Extensive green roof: an extensive green roof has growing medium that is 6 inches or less deep
  • Filter fabric: a lightweight, rot-proof material laid over or included as part of a drainage layer to keep the growing medium in place and thereby prevent fine particles from blocking the drainage system. [4]
  • Flashing: the weatherproof material installed between roof sheathing (or wall sheathing) and the finish materials to help keep moisture away from the sheathing [5]
  • Growing medium: the particulate matter or substrate that anchors the plant roots to sustain the plant growth [6]
  • Intensive green roof: an intensive green roof has growing medium that is more than 6 inches deep
  • Irrigation system: Systems which deliver moisture to the growing medium making it available for plant use [7]
  • Leak detection system: Leak detection systems allow for detecting and pinpointing the exact location of leaks in the waterproof membrane
  • Lifecycle cost: The capital and operational cost of a construction item or system during the estimated useful life of the building [8]
  • Live load: All equipment and people on the roof. They are not permanent elements [9]
  • Maximum media density: the density of a mixed media material determined after it has been subjected to a specific amount of compaction and hydrated by immersion to simulate prolonged exposure to both foot traffic and rainfall (ASTM E 2399-05)
  • Maximum Media Water Retention (MMWR): terminology used in ASTM E 2399-05 for FLL Maximum Water Capacity (MWC); the quantity of water held in a media at the maximum media density. This is a useful measure of the capacity of a media to hold water under drained conditions.
  • Maximum Water Capacity (MWC): terminology used in FLL guidelines for Maximum Media Water Retention (MMWR); the quantity of water held in a media at the maximum media density. This is a useful measure of the capacity of a media to hold water under drained conditions.
  • Membrane protection layer: A material used to protect the waterproofing membrane and/or insulation layer during the installation of a green roof [10]
  • Modular green roof: A green roof system which combines one or more layers in a single pre-manufactured product (e.g. drainage, growing medium, and plants) [11]
  • Performance Specifications: allow the contractor to choose what products to install and how to install them as long as specified performance goals are met. Performance specifications allow the contractor more flexibility and innovation compared to descriptive specifications, and therefore often result in more economical bids.
  • Pre-grown mats: Mats filled with growing medium and delivered to the site pre-grown with green roof vegetation, typically Sedums. Pre-grown mats are delivered in rolls like sod. The mats can be biodegradable or permanent
  • R factor: The measure of thermal resistance. R = K·m²/ [12]
  • Root barrier: green roof component that prevents plant roots from damaging the waterproofing membrane. (link to description in 5E)
  • Water Permeability: the coefficient, which when multiplied by the hydraulic gradient will yield the apparent velocity with which water, at 68°F (20°C) will move through a cross-section of media. The conditions created in this method apply to freely-drained media where the free water surface is level with the upper surface of the media layer (such as, impending accumulation of water above the surface of the media).
  • Water retention layer: Typically a water holding fabric or a plastic sheet with cup-like depressions, the water retention layer holds water for later use by plants.
  • Wind uplift: a net upward force that occurs when the pressure below a roof is greater than above it.

Related pages

This page was last edited on 17 January 2023, at 14:41.