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[[File:Pass Filter Bed green roof.PNG|400px|thumb|right|Fully constructed green roof.]]

[[File:Pass Filter Bed green roof.PNG|500px|thumb|right|Fully constructed green roof.]]

 

=Overview=

=Overview=

[[Green roofs]] are composed of several layers (waterproof membrane or existing membrane, root barrier, drainage layer, filter fabric, growing medium) that support the growth of plants and other vegetation on top of a roof. Growing medium depth determines which plants can be planted, and the components of green roofs can either be loose-laid or fused together. The proper installation of green roofs can help to achieve water balance targets, promote biodiversity and provide green space.

[[Green roofs]] are composed of several layers (waterproof membrane or existing membrane, root barrier, drainage layer, filter fabric, growing medium) that support the growth of plants and other vegetation on top of a roof. Growing medium depth determines which plants can be planted, and the components of green roofs can either be loose-laid or fused together. The proper installation of green roofs can help to achieve water balance targets, promote biodiversity and provide green space. Some key resources for green roof construction include the following:

=Types=

=Types=

There are two main types of green roof systems: extensive and intensive.

There are two main types of green roof systems: extensive and intensive.

#Extensive green roofs have growing medium depths of 10 cm to 15 cm (0.1 m to 0.15 m), maximum structural weight loads of 250 kg/m², and vegetation is primarily limited to sedum ''spp'' or commonly known as stone crop. For information on plants that are often included in extensive green roofs, see [[Green roofs: Planting|this list]].

#'''Extensive green roofs''' have growing medium depths of 10 cm to 15 cm (0.1 m to 0.15 m), maximum structural weight loads of 250 kg/m², and vegetation is primarily limited to sedum ''spp'' or commonly known as stone crop. For information on plants that are often included in extensive green roofs, see [[Green roofs: Planting|this list]].

#Intensive green roofs have growing medium depths greater than 15 cm (0.15 m), no maximum structural weight load. Intensive green roofs can be planted with deeply rooted plants, making them suitable for various [[Perennials: List|native flowers]], [[trees]] and [[shrubs]]. Pedestrian pathways and gathering areas can also be incorporated into the design of intensive green roofs.  

#'''Intensive green roofs''' have growing medium depths greater than 15 cm (0.15 m), no maximum structural weight load. Intensive green roofs can be planted with deeply rooted plants, making them suitable for various [[Perennials: List|native flowers]], [[trees]] and [[shrubs]]. Pedestrian pathways and gathering areas can also be incorporated into the design of intensive green roofs.  

Within these two types of green roofs are two installation type systems:

Within these two types of green roofs are two installation type systems:

#Modular system: green roof component layers are fused together as a moveable modular block system that can be linked together with other green roof blocks to form the green roof. This type of system typically forms an extensive green roof type and are used where roofs are sloped and flat.

#'''Modular system''': green roof component layers are fused together as a moveable modular block system that can be linked together with other green roof blocks to form the green roof. This type of system typically forms an extensive green roof type and are used where roofs are sloped and flat.

#Layered system: all components' layers are loose laid as individual layers. This type of system can form both extensive and intensive green roofs and used typically on flat roofs.

#'''Layered system''': all components' layers are loose laid as individual layers. This type of system can form both extensive and intensive green roofs and used typically on flat roofs.

=Component description=

=Component description=

[[File:Layers green roof.PNG|thumb|right|400px|Generalized cross-section view of a green roof showing key components and common layers that make up this LID BMP (TRCA, 2018)<ref name="example1" />]]

[[File:Layers green roof.PNG|thumb|right|400px|Generalized cross-section view of a green roof showing key components and common layers that make up this LID BMP (TRCA, 2018).<ref name="example1"> TRCA. 2018. Fact Sheet - Inspection and Maintenance of Stormwater Best Management Practices: Green Roofs. https://sustainabletechnologies.ca/app/uploads/2018/02/Green-Roofs-Fact-Sheet.pdf</ref>]]

[[file:GRalllayers.JPG|400px|thumb|right|Layered system green roof with all component layers showing. A key benefit of green roofs is  (Photo source: CVC)]]

[[file:GRalllayers.JPG|400px|thumb|right|Layered system green roof with all component layers showing. A key benefit of green roofs is  (Photo source: CVC)]]

*Vegetation free zone: separates the green roof perimeter from the roof perimeter and other structures on the roof (e.g., vents), that is kept devoid of vegetation and natural debris.

*Vegetation free zone: separates the green roof perimeter from the roof perimeter and other structures on the roof (e.g., vents), that is kept devoid of vegetation and natural debris.

=Key construction steps=

=Key construction steps=

{| class="wikitable"

{| class="wikitable"

|+ Stage 4 guidance for vegetated LIDs and permeable pavements

|+ Green roof construction steps

 

 

 

 

 

|-

|-

 

 

|-

|-

| --

|'''Modular system'''

|stabilizing contributing drainage area

|

 

 

#Sweep and blow the roof membrane clear and free of dirt, debris, and any sharp objects (such as flash clippings)

#Sweep and blow the roof membrane clear and free of dirt, debris, and any sharp objects (such as flash clippings)

#Inspect the waterproof membrane for any potential damage prior to installing root barrier

#Inspect the waterproof membrane for any potential damage prior to installing root barrier

#Install green roof perimeter or vegetation free zones (if applicable) a minimum 2 feet from parapet wall and around other critical infrastructure such as vents or roof drains

#Install green roof perimeter or vegetation free zones (if applicable) a minimum 2 feet from parapet wall and around other critical infrastructure such as vents or roof drains

#Install the root barrier (if applicable) on top of the roof membrane.  

#Install the root barrier (if applicable) on top of the roof membrane.  

##Ensure sheet is goes up the parapet wall the full height of the green roof system (if applicable).

#*Ensure sheet is goes up the parapet wall the full height of the green roof system (if applicable).

##Where additional root barrier sheets are laid side by side, a minimum of 30 cm overlap between sheets is needed.  

#*Where additional root barrier sheets are laid side by side, a minimum of 30 cm overlap between sheets is needed.  

##Make appropriate slits in root barrier with a retractable knife (away from existing waterproof membrane) to allow installation around roof infrastructure such as drains, air vents and stacks

#*Make appropriate slits in root barrier with a retractable knife (away from existing waterproof membrane) to allow installation around roof infrastructure such as drains, air vents and stacks

##Please note that modular systems often include a root barrier built into the system but some systems recommend doubling up  

#*Please note that modular systems often include a root barrier built into the system but some systems recommend doubling up  

#Install the modular system according to manufacturer specifications or green roof design

#Install the modular system according to manufacturer specifications or green roof design

#If modular system is installed on a slope roof, the system will need to be anchored according to manufacturer specifications or design

#If modular system is installed on a slope roof, the system will need to be anchored according to manufacturer specifications or design

#Backfill vegetation free zones with clear stone (if applicable)

#Backfill vegetation free zones with clear stone (if applicable)

===Layered system===

|'''Layered system'''

#Sweep and blow the roof membrane clear and free of dirt, debris, and any sharp objects (such as metal flashing clippings)

#Sweep and blow the roof membrane clear and free of dirt, debris, and any sharp objects (such as metal flashing clippings)

#Inspect the waterproof membrane for any potential damage prior to installing the root barrier

#Inspect the waterproof membrane for any potential damage prior to installing the root barrier

#Install green roof perimeter or vegetation free zones (if applicable) a minimum 2 feet from parapet wall and around other critical infrastructure such as vents or roof drains root free zone. Green roof perimeter may consist of metal edging which will be installed according to design and/or manufacturer’s specifications

#Install green roof perimeter or vegetation free zones (if applicable) a minimum 2 feet from parapet wall and around other critical infrastructure such as vents or roof drains root free zone. Green roof perimeter may consist of metal edging which will be installed according to design and/or manufacturer’s specifications

#Install the root barrier (if applicable) on top of the roof membrane according to design or manufacturer specifications.  

#Install the root barrier (if applicable) on top of the roof membrane according to design or manufacturer specifications.  

##Ensure sheet goes up the parapet wall the full height of the green roof system (if applicable).

#*Ensure sheet goes up the parapet wall the full height of the green roof system (if applicable).

##Where additional root barrier sheets are laid side by side, a minimum of 30 cm overlap between sheets is needed.  

#*Where additional root barrier sheets are laid side by side, a minimum of 30 cm overlap between sheets is needed.  

##Make appropriate slits in root barrier with a retractable knife (away from waterproof membrane) to allow installation around roof infrastructure such as drains, air vents and stacks

#*Make appropriate slits in root barrier with a retractable knife (away from waterproof membrane) to allow installation around roof infrastructure such as drains, air vents and stacks

##Install drainage layers on top of the root barrier according to design or by manufacturers specifications

#*Install drainage layers on top of the root barrier according to design or by manufacturers specifications

#Install filter layer according to design and manufacturer’s specifications. Ensure 30 cm overlap between adjacent rows and it runs up green roof edging (perimeter) the full thickness of the green roof

#Install filter layer according to design and manufacturer’s specifications. Ensure 30 cm overlap between adjacent rows and it runs up green roof edging (perimeter) the full thickness of the green roof

#Place green roof growing medium to specified depth within the design or manufacturer’s specifications. Growing media is typically blown onto the filter fabric layer by blower truck.

#Place green roof growing medium to specified depth within the design or manufacturer’s specifications. Growing media is typically blown onto the filter fabric layer by blower truck.

#If rolled vegetated mat system, take sedum clippings and infill sparsely vegetated areas

#If rolled vegetated mat system, take sedum clippings and infill sparsely vegetated areas

#Install irrigation system according to design and/or manufacturer’s specifications

#Install irrigation system according to design and/or manufacturer’s specifications

<gallery mode="packed" widths=300px heights=300px>

<gallery mode="packed" widths=200px heights=200px>

GRPerimeter.JPG | Green roof perimeter installation (Photo Source: CVC)

GRPerimeter.JPG | Green roof perimeter installation (Photo Source: CVC)

GRdrainagelayer.JPG | Green roof root barrier and drainage layer installation (Photo Source: CVC)

GRdrainagelayer.JPG | Green roof root barrier and drainage layer installation (Photo Source: CVC)

Grfinishedsoil.JPG | Finished installation of green roof soil media prior to vegetation (Photo Source: CVC)  

Grfinishedsoil.JPG | Finished installation of green roof soil media prior to vegetation (Photo Source: CVC)  

GRveginstall.JPG | Completed installation of green roof sedum vegetation (Photo Source: CVC)

GRveginstall.JPG | Completed installation of green roof sedum vegetation (Photo Source: CVC)

Green Roof Shed.JPG | Modular green roof system

Green Roof Shed.JPG | Modular green roof system (Newtben33, 2013)<ref>Newtben33. 2013. Green Roof Shed. Photo. Accessed 21 September 2022. https://commons.wikimedia.org/wiki/File:Green_Roof_Shed.JPG</ref>

Toronto City Hall Podium green roof by LiveRoof, July 2010.jpg | Toronto City Hall Podium green roof by LiveRoof, July 2010

Toronto City Hall Podium green roof by LiveRoof, July 2010.jpg | Toronto City Hall Podium green roof by LiveRoof, July 2010 (GreenRoofGardener, 2010)<ref>GreenRoofGardener. 2010. Toronto City Hall Podium green roof. Photo. Accessed 21 September 2022. https://commons.wikimedia.org/wiki/File:Toronto_City_Hall_Podium_green_roof_by_LiveRoof,_July_2010.jpg</ref>

</gallery>

</gallery>

#Prior to hand-off points in the construction sequence when the contractor responsible for the work changes (i.e., hand-offs between the building and green roof installation contractors);  

#Prior to hand-off points in the construction sequence when the contractor responsible for the work changes (i.e., hand-offs between the building and green roof installation contractors);  

#After large storm events (e.g., 15 mm rainfall depth or greater) to ensure roof drainage or flow diversion devices are functioning and adequately maintained.

#After large storm events (e.g., 15 mm rainfall depth or greater) to ensure roof drainage or flow diversion devices are functioning and adequately maintained.

Additional inspections may be needed depending on the number of layers in the green roof design (e.g., insulation, root barrier, and growing medium structural support layers) and may be required to comply with product warranty conditions. The green roof product vendor or designer should provide further guidance in this regard, specific to the system or product being installed.

Additional inspections may be needed depending on the number of layers in the green roof design (e.g., insulation, root barrier, and growing medium structural support layers) and may be required to comply with product warranty conditions. The green roof product vendor or designer should provide further guidance in this regard, specific to the system or product being installed. A checklist of construction inspection steps can be found on the [[Inspection and Maintenance: Green Roofs]] page.

=Mistakes to avoid=

=Mistakes to avoid=

=References=

=References=