Planning considerations - Living Roofs in Integrated Urban Water Systems - page 61

Plants

Growing medium

ENGINEER +
LANDSCAPE ARCHITECT

Geotextile

ENGINEER +
LANDSCAPE ARCH I TECT

Drainage layer

Waterproo ng
membrane integrated
root barrier

ARCHITECT

ARCHITECT

Insulation
Vapour barrier

Roof slab/deck

Warm roof assembly

Plants

Growing medium

ENGINEER +
LANDSCAPE ARCHITECT

Geotextile

Drainage layer

ARCHITECT

Insulation

Waterproo ng
membrane integrated
root barrier

Vapour barrier

Roof slab/deck

Inverted roof assembly

Figure 3.5
Warm and inverted roof
cross-sections

architect. The warm versus inverted nomenclature refers to the location of the
insulation in reference to the waterprooing layer. In the warm roof scenario,
the insulation is below the waterprooing membrane. Water drains through the
growing medium and runs along the drainage layer that sits on the waterprooing
membrane to the roof drain locations.
In the inverted roof scenario, the insulation is installed above the waterprooing
membrane. Water drains through the growing medium. A portion of the water
then runs above the insulation to the drainage points. The remaining water drains
vertically through the gaps between the insulation layer boards, and then runs
above the waterproof membrane to drain locations. Because the insulation must
remain dry (to avoid the loss of its insulative properties), the assembly, especially
the drainage layer, has to be partially designed to promote air circulation. The
drainage layer acts as an air circulation zone between the insulation and geotextile
layer allowing evaporation to reduce sogginess in the insulation layer. Alternatively,
the insulation can be sandwiched between an additional air circulation layer and
the drain mat. This allows air circulation on top of and below the rigid insulation.