Integrating stormwater performance and architectural design - Living Roofs in Integrated Urban Water Systems - page 119

Figure 4.4
Roof slope scenarios

Available
water

Dry

Wet Wet

Sloped roof scenario 1

Available
water

Dry Wet Dry

Polystyrene Polystyrene

Sloped roof scenario 2

Available
water

Dry Wet Dry

Sloped roof scenario 3

maintenance, and minimizes plant moisture stress. Growing medium stability,
stormwater mitigation performance, vegetation selection and safety of access may
be affected by slope and roof pitch. The visual experience may be enhanced, or
eliminated.
Despite potential challenges, living roofs are nonetheless capable of being
integrated onto more steeply pitched and/or curved roof structures. In Germany,
for example, the FLL recommends that living roofs have a maximum slope of 45°
(100 percent) for pitched roofs and a minimum slope of 1.1° (2 percent) for lat
roofs (FLL 2008). In some stormwater design manuals published by regulatory
agencies (e.g., Auckland, New Zealand and NCDENR draft), living roofs with
slope greater than 15° are not eligible for stormwater control credits.