Slide 1GREEN ROOFS
Hanging Gardens of Babylon, 800-600 BC
Viking Sod Roofs, Middle Ages Great Plains Sod Roofs, 19th
Century
HISTORY
Underground Houses, 1960’s – 70’s
Contemporary Extensive Green Roofs, 1980’s – Present
History
DEFINITIONS GREEN ROOF: an area of planting built up on a roofed
structure below, above, or at grade, that is separated from the
natural ground by a man-made structure. A green roof is an
extension of the existing roof which involves the use of a root
repellant system, a drainage and filter layer, a growing medium and
plants.
EXTENSIVE ROOF: low-to-no maintenance green roof landscaping
consisting of shallow soil depths (<6”) with plant varieties
restricted to primarily mosses, herbs, and grasses capable of
withstanding harsh growing conditions (i.e., drought, wind,
frost).
INTENSIVE ROOF: green roof landscaping requiring regular
maintenance (i.e., watering, fertilizing) consisting of deeper soil
depths (>6”) with a wide variety of plants, including shrubs and
small trees.
Green Roof Infrastructure also referred to as: •living roofs
•vegetated roofs •rooftop gardens •brown roofs (spontaneously
seeded) •eco-roofs.
Definitions
Green Roof Categories
Green Roof Categories
Green Roof Categories
• Increased Solar Panel Efficiency
• Fire Prevention
• Meeting Regulatory Requirements for Water Treatment of Urban
Runoff
• Reduce Community Resistance to New Developments
• LEED
• Marketing Opportunities
Energy Efficiency
•In summer, the green roof protects the building from direct solar
heat. •In winter, the green roof minimizes heat loss through added
insulation on the roof. •Energy conservation translates into fewer
greenhouse gas emissions.
Green roofs reduce the heat flux through the roof
Source: Green Roof Innovations
Solar Panels
Keeping a constant temperature on the roof ensures a better
efficiency of solar panel energy production
• North American roofs have an average lifespan of 10-15 years –
Average across climates
and membrane types
• Waterproofing membranes in green roof assemblies have lasted over
40 years in Germany.
Increased Membrane Durability
Green Roofs can: • Reduce or even eliminate stormwater/wastewater
charges • Reduce the need or size of stormwater management
ponds/cisterns cost savings
Green roofs can help achieve up to 14 points in 5 different
categories :
LEED
•Storm water retention •Reducing heat island effects •Energy
efficiency •Water use efficiency •Design innovation
Salmon Creek School LEED Platinum
Green roofs improve:
• Improved Air Quality
Storm Water Management: Quantity
Runoff from green roofs have reduced levels of
metals, PAHs, other pollutants, and bacteria due
to their capacity for:
Storm Water Management: Quality
Plant leaves trap dust particles from the air, and
evapotranspiration cools ambient temperatures.
Improved Air Quality
• Less ground level ozone + less heat = less smog. • Reduced Urban
Heat Island profile. • Less need for health care services result in
societal cost savings.
• Creation of migration islands for species of insects and
birds
• Improved urban habitat • Stabilization of native
and local populations • Protection of
endangered plants • Rooftops can serve as
refuge for creatures that struggle for survival (like ground
nesting birds)
Source: Dusty Gedge Source: Soprema Canada
Source: Bradley Rowe
• Urban Agriculture
• Public Education
• Waste Diversion
Green roofs contribute to Low Impact Development / Smart Growth
Planning:
Aesthetics & Amenity/Recreational Space
Source: Optigreen/Ingrid Fiebak
• Encouraging community gardens and food production
• Extending commercial and recreational space
• Creating private amenity spaces
• Improved overall health, job satisfaction and productivity
Improved Health and Well-Being
Noise Reduction • Extensive green roofs can reduce sound by 40
decibels • Intensive green roofs can reduce sound by 46-50
decibels
Source: Ecofriend.com
• Food security • Increased
• Reduced household expenditure
Urban Agriculture
Public Education
School of Art, Design and Media at Nanyang Technological University
in Singapore
Waste Diversion
• The doubled life expectancy of a waterproofing membrane can half
the number of membranes entering dumps
• Opportunities to recycle aggregate and compost
DESIGN & IMPLEMENTATION
Brooklyn Botanic Garden Master Plan, H M White Site
Architects
• Major design objectives • Budget • Accessibility • Physical size
of a project • Time • Degree of integration with
building systems • System type (loose laid v.
modular) • Green roof category
Scope
a combination of: • Live Loads • Dead Loads Structural loading
capacity
will determine: • Accessibility • Type of green roof
(extensive/intensive) • Choice of plants • Composition of
growing
medium
• Installation
• Maintenance
Loose Laid Systems
Source: American Landscape
How They Work
Biology – Growing Medium, Plants
• Inappropriate plant selection
• Growth media collapse
– Polyvinyl chloride (PVC), – Thermoplastic olefin membrane
(TPO)
(EPDM)
Waterproof Membrane
Application: Mop down, liquid applied, single ply The seams can be
waterproofed by heat welding, chemical adhesive, or hot applied
bitumen
Root Barrier
fabric • PVC waterproofing
membrane • TPO waterproofing
polystyrene, or coconut mats
systems).
• Drain structures and openings - Roof drains (e.g. round deck,
domed, flat topped, lateral, and control flow drains) - Gutters and
eaves troughs
• Drain pipes
Filter Fabric
• Polypropylene- polyethylene mats.
compaction.
• Free of material which may degrade, clog, or corrode drainage or
waterproofing system.
• Retention of nutrients/moisture.
• Offer a high void (air volume) ratio even when saturated.
• Sufficiently porous for internal aeration. • Minimal contribution
to weight load.
• Resistant to heat and rot.
• An ability to anchor plants.
• Readily drainable.
• Retention of nutrients/moisture.
• Structural loading capacity
Vegetation
climate
• Inadequate drainage
• Improper maintenance
Irrigation
• Overhead • Spray • Drip irrigation • Capillary irrigation • Base
drip or trickle
irrigation • Water retention mats
Maintenance The maintenance plan for the plant material
should include: • Semi-annual weeding • Steps to maintain a coarse,
very dry surface
on the green roof , making germination of weed seeds less
likely
• Steps for the prevention of leaf build up, causing a fungal
disease in late autumn
• Removal of any plant that shows signs of disease
• Fertilize when and if necessary
DIY Green ROOF