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→Planning Considerations
To maximize the utility of a green roof as a low impact development tool, coverage with planting should be maximized. In many cases this means only inaccessible spaces are used.
To maximize the utility of a green roof as a low impact development tool, coverage with planting should be maximized. In many cases this means only inaccessible spaces are used.
<h4>Amenity</h4>
<h3>Amenity</h3>
Roof gardens with a high proportion of impermeable surface are popular in high rise developments. These amenity terraces are often described as green roofs, but the LID benefit applies only to the vegetated areas. The stormwater benefit of all kinds of green roofs is maximized by combined with [[Rainwater Harvesting|rainwater harvesting]] for subsequent irrigation. Sedum and native species have all been shown to thrive with daily irrigation to saturation[http://grit.daniels.utoronto.ca/green_roof_image_index/#].
Roof gardens with a high proportion of impermeable surface are popular in high rise developments. These amenity terraces are often described as green roofs, but the LID benefit applies only to the vegetated areas. The stormwater benefit of all kinds of green roofs is maximized by combined with [[Rainwater Harvesting|rainwater harvesting]] for subsequent irrigation. Sedum and native species have all been shown to thrive with daily irrigation to saturation[http://grit.daniels.utoronto.ca/green_roof_image_index/#].
Rooftop farming is also becoming common in some Ontario cities. Again consideration should be given to the proportion of the roof actually planted. Where large open expanses of roof are being cropped, measures may be required to reduce erosion of exposed planting medium. Any digging or furrows will reduce the stormwater benefit.
Rooftop farming is also becoming common in some Ontario cities. Again consideration should be given to the proportion of the roof actually planted. Where large open expanses of roof are being cropped, measures may be required to reduce erosion of exposed planting medium. Any digging or furrows will reduce the stormwater benefit.
<h4>Biodiversity</h4>
<h3>Biodiversity</h3>
Biodiversity opportunities are optimized by planting a variety of species. General advice on this has been prepared by the City of Toronto[https://www1.toronto.ca/City%20Of%20Toronto/City%20Planning/Zoning%20&%20Environment/Files/pdf/B/biodiversegreenroofs_2013.pdf]. In the long term, the richness of species increases owing to 'volunteer species'. The desirability of this diversity varies with the aesthetic concerns of the green roof owner. </p>
Biodiversity opportunities are optimized by planting a variety of species. General advice on this has been prepared by the City of Toronto[https://www1.toronto.ca/City%20Of%20Toronto/City%20Planning/Zoning%20&%20Environment/Files/pdf/B/biodiversegreenroofs_2013.pdf]. In the long term, the richness of species increases owing to 'volunteer species'. The desirability of this diversity varies with the aesthetic concerns of the green roof owner.
<h4>Design for Maintenance</h4>
<h3>Design for Maintenance</h3>
Detailed inspection and maintenance advice can be found in [http://www.sustainabletechnologies.ca/wp/wp-content/uploads/2016/08/LID-IM-Guide-7.6-Green-Roofs.pdf Sustainable Technologies' LID I&M guide.]
Detailed inspection and maintenance advice can be found in [http://www.sustainabletechnologies.ca/wp/wp-content/uploads/2016/08/LID-IM-Guide-7.6-Green-Roofs.pdf Sustainable Technologies' LID I&M guide.]
The primary operational concern for operating a green roof is the development of a leak. Green roofs protect the roof membrane from UV damage and should increase the lifespan of the roof. However, in the event that a leak is discovered a section of green roof would have to be removed for access. Some proprietary systems appear to be easier to remove and replace. This may come at a cost, as the rainwater retention of the system is somewhat reliant on continuous coverage of the green roof surface. </p>
The primary operational concern for operating a green roof is the development of a leak. Green roofs protect the roof membrane from UV damage and should increase the lifespan of the roof. However, in the event that a leak is discovered a section of green roof would have to be removed for access. Some proprietary systems appear to be easier to remove and replace. This may come at a cost, as the rainwater retention of the system is somewhat reliant on continuous coverage of the green roof surface. </p>