SuDS in London - a guide

3.2 Structures
Roofs and walls can provide the first
point of interception as part of the SuDS
management train.
Living roofs are an effective way to
integrate green infrastructure, no matter
how intense the development. The term
living roofs include ‘green’ (planted), ‘blue’
(water attenuation) and ‘brown’ (recycled
substrate) roofs. The three types of living
roofs can be characterised by:
• Extensive roofs: these have
varying substrate depths and
vegetation that generally includes
grasses and wildflowers, creating
minimal loading on structures
• Intensive roofs: these typically
have deeper substrates supporting
a range of vegetation. This puts
larger loadings on the structure
• Blue roofs: these attenuate
through vegetated substrate
specification and drainage design
Green walls are vegetated walls that are
supported on cables, cellular systems or
self-clinging and unsupported. They can
be proprietary systems with irrigation, or
formed over time by planting climbing
plants into the ground that are more
self-sufficient.
Benefits
Living roofs and green walls provide
multiple benefits and contribute to the
Green Infrastructure Vision for London.
They reduce rainwater runoff rates,
offset the urban heat island effect and
filter air pollution.
Benefits include:
• Water quantity: living roofs
intercept and attenuate rainwater.
They allow a reduced discharge
rate through evaporation and
transpiration. Green walls can use
recycled water for irrigation
• Water quality: living roofs treat
water through a variety of physical,
biological and chemical processes
within the soil and root uptake zones.
They regulate surface water runoff
temperature that could adversely
affect ecology of local water bodies
• Amenity: living roofs can improve
the look of roofscapes, while
rooftop parks and gardens act as
Proprietary green wall system
an educational and urban farming
resource. Green walls soften the
hard city environment, reducing air
temperatures while being space efficient
• Biodiversity: Living roofs safeguard,
enhance, restore and create habitat
with no additional land take. They
provide important habitat stepping
stones and contribute to London’s
natural capital. In particular, they
provide refuge for rare invertebrates.
Green walls provide vertical habitats
for nesting and food for pollinators
33 3 SuDS components