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→Component description
=Component description=
=Component description=
*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.
*Root barrier: often a clear plastic sheet, the root barrier layer protects the water-proofing membrane from root penetration and degradation by microbial activity.
*Drainage layer: provides void space for excess water to drain from the growing media that is either stored for later uptake by plants or allowed to flow to roof drain.
*Filter fabric or geotextiles: are used to retain growing media and prevent migration out of green roof system
*Growing media will vary according to the green roof system/product installed but is generally designed to be porous and lightweight with adequate fertility and drainage capacity to support plant growth and allow for absorption and infiltration of water.
*Vegetation: Green roofs rely on vegetation (i.e., sedums/succulents, grasses, herbs, wildflowers and for intensive green roofs, shrubs and trees) to intercept, absorb and evapo-transpire stormwater. Vegetation can be installed as mats or as plugs or pots based upon the green roof design.
*Overflow outlets: Flows exceeding the storage capacity of the BMP are conveyed to an adjacent drainage system via an overflow outlet structure and the roof drainage system.
*Irrigation System (if applicable): Most green roofs will require periodic irrigation, especially during the first 2 months of the establishment period.
*Leak detection system (if applicable): leak detection systems should be used to periodically check for the presence of leaks in the water-proofing membrane.
=Key construction steps=
=Key construction steps=