This document provides an overview of green roof systems and what is needed to implement them effectively. It discusses the main reasons for installing green roofs, including stormwater management, air pollution reduction, and increasing green space. It also covers green roof basics like extensive systems, evaluating options, and design tips. Installation processes and innovative techniques are reviewed. Standards and protocols for ensuring proper performance are also examined.

1. Green Roof Systems
What you need to know to implement effective green roofs
Kees Govers
LiveRoof Ontario Inc
Mt Brydges, ON

2.  Green Roof Basics
 Extensive green roof systems
 Evaluating green roof systems
 Design tips
 An installation in 4 slides
 Innovative new greening techniques
 Questions

3.  Main reasons for installing green roofs
 Stormwater management
 Air pollution reduction
 Urban heat island reduction
 Energy use reduction
 Replacement or increase of green space
 Roof life extension
 Aesthetics
 Green roof mandates
 Contribution to LEED credits

4. What makes a green roof work?
 Plants utilise solar radiation
 Photosynthesis creates carbohydrates and O2 from
H2O and CO2
 Respiration produces plant growth and CO2
 Respiration and photosynthesis create transpiration
 Transpiration draws H2O and O2 from substrate
along with nutrients
 Growing medium absorbs and holds H2O and O2
until transpired
 Filtration and buffering takes place in the process

5. LEED Sustainable Sites Credits 6.1 & 6.2
Stormwater Design: Quantity control & Quality control
 Storm Water Retention
 Storm Water Detention
 Storm Water Filtration

6. Storm Water Retention
Defined by the absorptive capacity of
Green roof system
 Growing media 20-45% by volume
 Plants depends on plant type and turgidity
 Water retention fabrics
 Water retention cups
Green roof system auxiliaries
 Cisterns

7. Where does the retained water go?
 Evapotranspiration
 Succulents (facultative CAM)
 Grasses (mostly C-4)
 Perennials (mostly C-3)
 Photosynthesis
 Surface evaporation

8.  What happens during a drought?
 Succulents
 Switch to CAM
 Reduce evapotranspiration
 Cuticles get thicker
 Plants physically shrink
 Plants loose mass (mostly water)
 Death occurs after very long drought
 Recovery time from drought: less than 24 hours

9. Allium schoenoprasum ‘Forescate’
Sedum ellacombianum

10.  What happens during a drought
 Grasses (C-4)
 Reduce evapotranspiration
 Cuticles get thicker
 Plants abort flowers and seeds
 Plants shrivel up
 Plant crown goes dormant
 Death occurs after variable fairly long drought
 Recovery time from drought: up to several weeks

11. Koeleria macrantha
Schyzachyrium scoparium

12.  What happens during a drought
 Perennials (C-3)
 Reduce evapotranspiration
 Cuticles get thicker
 Plants abort flowers and seeds
 Plants shrivel up
 Plant crown goes dormant
 Death occurs after variable length drought
 Recovery time from drought: weeks to months

13. Penstemon digitalis Aquilegia canadensis

14.  Stormwater detention and filtration
 Effectiveness depends on
 Stormwater retention
 Rainfall intensity
 Saturated conductivity of growing medium
 Plant density
 Denser plantings prevent surface runoff

15.  Storm water quality improvement
 Buffers water pH
 Filters pollutants
 Organic compounds
 Heavy metals
 Particulate matter

16. Reduction by deposition on foliage
Particularly effective for
 Particulates
 NO, NO2
2011 Lancaster University Study
Particulates up to 60% reduction
NO, NO2 up to 40% reduction

18. Sustainable Sites credit 7.2 Heat island Effect: Roof
Lower roof temperatures
 Reduced heat transfer into buildings
 Lower HVAC loads
 Reduced roofing membrane stress
 Improved photo voltaic cell performance
 Lower temperatures above the roof

21. How does a green roof compare to a white roof?
 Lower surface temperature in the summer sun
 Higher temperature in the winter
 Effectiveness does not depend on cleanliness
 Does not cause glare
 Does not bounce solar radiation to other surfaces
 Does not deteriorate under UV light

24. Intensive Extensive
Growing medium depth 300mm and deeper 65mm to 150mm
Saturated load 400 kg/m2 and over 50 – 250 kg/m2
Plants Trees and shrubs Succulents, grasses,
perennials
Maintenance High low
Irrigation Always Depends on design

25.  Four critical factors
 Drainage
 Growing medium
 Plants
 Plant coverage
Nothing else matters
 A stressed green roof doesn’t function properly!
 A dead green roof doesn’t function !!!!

26.  Built in place systems
 Pre-grown blankets
 Modules
 Hybrid Modules
Stoney Creek Library London

27. • Built up system
• Hand planted
• Slow growing due to heat and cold
• Vulnerable to weeds
• High maintenance
27

28. Ottawa, ON, 1 season old
Grand Rapids, MI 1 yr old

29. • Takes a long time to grow in
• Mini monocultures of deciduous plants leave soil exposed
• Lacks succession in design
29

30. CMC Gatineau
MEC 1998 Mature built in place green roofs

31. Blanket installation
Blanket system assembly

32. Blankets as part of a built in place system

37. What industry wide protocols exist?
5 ASTM Standards (All based on German FLL Standard)
 ASTM E2396-05 standard test method for saturated
permeability of granular drainage media
 ASTME2397-05 Standard practice for determination of dead
loads and live loads associated with green roof systems
 ASTM E2398-05 Standard Test method for water capture and
media retention of geocomposite drain layers for green roof
systems
 ASTM E2399-05 Standard Test method for maximum media
Density for dead load analysis of green roof systems
 ASTM E2400-06 Standard guide for selection, installation and
maintenance of green roof systems

38.  Toronto Green Roof Standard
 Only comprehensive enforceable green roof
standard in North America
 FM Global approvals standard 4477 for
vegetative roof systems
 FLL Guideline for the planning, execution and
upkeep of green roof sites, release 2008

39.  Drainage
 Growing Media
 Plant Selections
 Edge effect
 Irrigation
 Wind uplift performance
 Maintenance requirements

40. Typical drainage layers
For built in place

43. Typical drain layer used under mats

46. Engineered growing medium
•Designed to remain on the roof, very durable
•No stabilizing agents should be needed
•No short term lightweight fillers
•No perlite or vermiculite
•No horticultural foam or Styrofoam beads
•No more than 5-6% organic matter (by pyrolysis test)
•No hydrogels (not legal in Canada for growing media)
• Falls within FLL Standard parameters

49. Poor Growing medium choice
•Too coarse
•Too little organic matter
•Tough for plants to establish

50. April 2010
Poor Growing medium choice
•Too much organic matter
•Poor aeration when saturated
Plants grow too fast initially
Plants start dying after about 4-5 years
May 2010

51. Very shallow growing medium

52.  Growing media specifications
 Be as specific as you can
 Demand an FLL test report
 At time of submission
 Just prior to installation
 For modules at time of filling
 Ask for physical samples
 Only accept substitutions is they meet the above
criteria

53. Get to know your supplier and their suppliers
 Plant producer
 Quality of plants
 Propagation facilities
 Production capacity
 Handling equipment
 Delivery equipment (for module suppliers)
 Installation equipment
 Blower trucks
 Conveyor belts
 Delivery racks

54. Stock beds

55. Production Capacity and equipment

57. Depends on:
 Depth of growing medium
 Design of the green roof
 Intended purpose of the green roof
 Irrigation or not

58. Succulents Grasses Perennials
Media <75mm With irrigation no No
Media 75 to 150mm yes With irrigation With irrigation
Media >150mm yes some some
Combination plantings are preferred
• Better winter survival
• Better drought survival
• Healthier plants

59. Plant installation limitations
Succulents Grasses Perennials
Seed Takes a long yes some
time
Cuttings Small window no No
Plugs Spring and fall Spring and fall Spring and fall
mats Spring and fall Spring and fall no
Pregrown modules Above 2 C Above 2 C Above 2 C

62. 150mm depth, no irrigation
• Aster
• Solidago
• Juniperus horizontalis
• Scabiosa
• Geranium
• Sedums
• Alliums
• Sempervivums
• Calamintha
• Nepeta
• Agastache

63. 2006 Timber Press
Snodgrass&Snodgrass
Best North American
book on extensive
green roofs
Regional LiveRoof Plant Selections Guide

64. Eglinton West Station

65. Victoria Park Station

66. Stoney Creek YMCA & Library, London

67. Toronto City Hall podium

68. • Exposed Edges
• No soil connectivity
• Plants dry out along edges
• Plant roots are affected by cold
• Slower growth as a result
68

69. • Exposed plastic and gaps between modules negatively affect plant performance
69

72.  Michigan State research (to be presented at CitiesAlive)
Based on 30 minute irrigation events
 Overhead irrigation
 25% more water applied than drip or sub
 20-30% run-off of total applied
 Even distribution
 Drip irrigation
 25% less water applied
 80% plus run-off of total applied
 Poor distribution
 Sub irrigation
 Worse in all respects than sprinkler or drip

73. Drip lines with 6” spacing (normal is 12”)
After 10 minutes
After 60 minutes
Waste water

74. Appropriate use of drip irrigation

75. Drip irrigation failure

77.  Relative costs and embedded energy
 Line spacing
 Sub: under entire green roof system
 Drip: 300mm spacing between lines
 Sprinkler: Up to 12 metre spacing between lines
 Installed cost in TO
 Sub: $40 -$60/m2
 Drip: $20-$35/m2
 Sprinkler: $15-$20/m2
 Maintenance
 Sub: near impossible
 Drip: clogged lines need to be replaced
 Sprinkler: easy maintenance and malfunction detection

79.  City of Toronto requires
 Wind uplift study of each building according to OBC
signed by a professional engineer
 Wind uplift pressures in kPa (or psf)
 2015 version of National Building code will require
wind uplift rating for:
 Roofing systems
 HVAC units
 PV installations
 Green roofs
 Pavers

80. How wind uplift pressure is calculated:
 Formulas in OBC
 Mathematical exercise
 Scale wind tunnel testing
 Usually done for building models of unusual shape
 Full size dynamic testing
 Testing on full scale products
 Test protocol developed by NRC Canada
 CSA A123.21-10

81.  CSA A123.21-10
 Dynamic wind uplift test protocol
 Test rating may be required for all green roof
systems.
 Untested systems will be rated at dry weight of
system
 Only one system tested to date.

82. Regent Park Block 24

86. Mature plants resist scour

87. Low maintenance planting

88. Medium maintenance planting

89. High maintenance planting

90. High maintenance

91.  Nutrition
 Preliminary findings at U of G
 Maintenance concentration of macro nutrient
important
 Source of nutrients is unimportant
 Healthiest plants at modest levels of nutrition
 Starving plants does not toughen them
 Overfeeding plants kills them

92. Install pavers, edging and irrigation before the plantings

93. Overhanging roofs require irrigation

94. Stone Pavers Installed against a South Facing Wall
Prevent scorching

95. Roof with Exposed Membrane Roof without Exposed Membrane

96. Distressed and Dead Plants Due to Excessive Foot Traffic

97. Severe traffic damage by other trades
Avoidable by proper sequencing

98. Plant Death Caused by Roof Vent Air stream

99. Roof Access Point with Stone Pavers

100. The Blank Canvas
•membrane replaced
•EFVM installed
•Asphalt flood coat applied

101.  Installation Day 1

102. Installation End of Day 2

103. Installation End of Day 4

106.  Greening can happen anywhere on any scale
 Exercise due diligence in selection and execution
 Don’t be afraid of innovative ideas

107. Contact Information
Kees Govers
LiveRoof Ontario Inc
23078 Adelaide Rd
Mount Brydges, ON
N0L 1R0 Canada
(519) 245-4039
kees@liveroofontario.ca
www.LiveRoof.ca
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