Case studies - Living Roofs in Integrated Urban Water Systems - page 149

2 TENTH FLooR “ECo- RooF ” (ExTENSIVE LIVING RooF )
Plant selection for this extensive living roof included native, drought-tolerant and
low-growing sedum varieties. This selection provides a viable habitat for small
living organisms, but provides little attraction level to local birds. Since the year
following project completion, the living roof has been active hotspot for bees -
an unintended but welcome achievement of biodiversity of the roof. In spring of
2012, an apiary was installed (Timmerman 2013). Bee activity has been encour-
aged in the areas not accessible to the Headquarters' staff, enabling continued
activity and safety of the building's occupants (Timmerman 2014).
The tenth loor living roof is comprised of a 100 mm growing medium. The
assembly was installed as a proprietary modular system (comprised of 30 cm × 60 cm
pre-grown trays), which along with the root barrier, was installed directly over the
TPO-membrane roof deck. The pre-grown trays were quick to assemble due to the
manageable size of the modules, produced an “instant green” result, and reduced
the initial establishment of weeds. Four years after completion, the trays have held,
plants are healthy, and very little maintenance has been required (Timmerman 2014).
The tenth loor living roof drains at a gentle 1.5 percent slope. Drains and
perimeter edges are ballasted with washed river rock. The maintenance pathway
along the outer edge of the roof was given generous proportions (for the roof
and glazing), respectively. Waterprooing was taken very seriously and, to date,
no leakages have been recorded (Timmerman 2014).
The roof elements feature a mixture of protected vegetated areas, patios
without barriers and patio with barriers. Life-safety features have been provided
through the use of guardrails around two of the patios and around the full
perimeter of the extensive living roof area.
3 EIGHTH FLooR “ECo- RooF ” (INTENSIVE LIVING RooF )
Located on the south side of the Port of Portland Headquarters building, the
intensive living roof and terrace is an outdoor amenity for both staff and visitors.
In a growing media depth of 300 mm and 600 mm, thrive a variety of ground
covers, ornamental grasses, shrubs and small trees. The roof is both an active
space for occupant use and a passive framing device, both locally and contextu-
ally. Deinition of form and sequestration of semi-private seating alcoves are
created by weathering steel planters. The plane of landscape is sloped upwards,
with shorter vegetation at the southwest edge of the roof and taller plants on
the northeast edge, foregrounding the forest beyond while providing visual and
acoustic screening of runways and the upper deck of the parking garage.
5.2.3 Single lot scale: Mirabella and The South Waterfront District,
Portland, Oregon, USA
5.2.3.1 Context
Located on the west bank of the Willamette River, one mile south of downtown
Portland, the South Waterfront Central District (SOWA) is a 42-acre former industrial