URBAN
Project funded
by theEU–DGEnvironment
L
andsurfacerelevant
forapplication
Artificial surface
Agriculture land
Forest and semi-natural areas
Wetlands
F
inancialcosts
(C
apital
,
operation
&
maintenance
)
Capital costs are likely to be higher when green roofs are retrofitting than when
they are being incorporated in a
newbuilding
. Capital costs range between €25-
130/m
2
for extensive design and €130-300/m
2
for intensive design.. Maintenance
costs are up to €55/ m² for each maintenance event on extensive green roofs.
D
esign
There should be multiple outlets from the green roof, to reduce the risks from
blockages. The structural roof strength must provide for the full additional load
of saturated green roof elements. The
waterproof membrane
should have
good root penetration resistance and substrate thicknesses should be between 100
and 250 mm.
Maintenance
(vegetation, membrane...) is important to ensure
continued effectiveness.
S
cale
Green roofs can be incorporated on
building roofs of any size.
Green roofs can be grown on any pitch
of roof, including vertical walls.
Green roofs are multi-layered systems that cover the roof of a building with
vegetation and/or green landscaping
over a drainage layer. There are two
types of green roof:
extensive
green roofs (sedum roofs, eco-roofs or living roofs) cover the entire roof area with lightweight, low growing, self-sustaining, low
maintenance planting.
Intensive
green roofs (roof gardens) are landscaped environments with high amenity benefits. Green roofs are designed to
intercept
rainfall
, which is slowed as it flows through the vegetation and a drainage layer.
Case studies:Green roofs inVienna,Austria;Green roofs inGeneva, Switzerland;Urbangreen roofs inHelsinki, Finland
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