Green roofs are structures with plantings installed above street level that provide environmental and aesthetic benefits. They enhance stormwater management by capturing rainfall and reducing runoff. Green roofs also help with temperature control, food production, and recreation. They are suitable for transect zones T2 through T6 and can be installed on flat or low-sloped roofs. Maintenance involves typical gardening tasks and ensuring plants are suited to the local climate. Green roofs have a higher initial cost than conventional roofs due to added weight and waterproofing requirements.

1. X. Green Roof
FILTRATION
T-Zones: T2, T3, T4, T5, T6 Slope: Steep, Moderate, Flat
N
Cost
: $$$ Soils: Poor, Medium, Good
T1
Maintenance: Medium Climate: Cold, Temperate, Hot
Dry, Moderately Wet, Wet
atural
A. Description
Structures with green roofs visually enhance communities with
plantings above the street level. They are a viable stormwater
management tool that captures rainfall in typically impervious
areas. The building produces less sheet flow to be managed at
R
Green Roof
ground level. In addition, they can provide food for the community,
T2
temperature control, architectural enhancement, and recreation.
ural
B. Use
Because a green roof is an addition to an individual building,
it is appropriate for use in T2, T3, T4, T5, and T6 transect zones.
A roof garden may be planted on a flat roof or a roof with a low
S
pitch. Roof gardens can use atypical gardening techniques, such
as hydroponics. This can make roof gardens produce more plenti-
ub-U
ful crops.
T3
C. Maintenance
rban
The upkeep for a green roof is similar to that of a normal
garden and includes seasonal maintenance. Plant selection must
ensure that species selected are appropriate for the climate.
D. Cost Gene
U
The cost of a green roof is higher than the average cost of
T4
a roof. The structure requires additional support for the weight
of vegetation and soils. The roof membrane must be waterproof
rban
ral
to ensure that no water leaks into the structure.
E. Resources
Nate Berg. “Top Down Greening in the Urban Core.” Planetizen.
(26 July 2006). <http://www.planetizen.com/node/20612>
ce
U.S. Environmental Protection Agency. ”Green Roofs” (Washington,
U
DC: USEPA, Heat Island Effect, Oct. 2007). < http://www.epa.
T5
nter
gov/heatisland/strategies/greenroofs.html>
rban
URBAN
CORE
T6
Light Imprint Handbook version 1.3 F37

2. FILTRATION
Natural
T1
Rural
Green Roof
T2
Sub-urban
T3
General
T4 - Green Roof - Portland, OR
Urban
T4
center
Urban
T5
URBAN
CORE
T6
T4 - Green Roof - Orlando, FL
F38 Light Imprint Handbook version 1.3

3. FILTRATION Green Roof
F39
T1 T2 T3 T4 T5 T6
N atural R ural S ub-U rban Gene ral U rban URBAN
U rban ce nter CORE
T3 - Green Roof - Findhorn, Scotland
version 1.3
Light Imprint Handbook