When Piano presented
his first sketches to the
Academy, he described his
idea for the roof by asking
his audience to imagine
a huge elevated swath of
the park, with the museum
tucked underneath it.
annual temperature is about 58 degrees Fahrenheit. The roof is also designed to absorb 98 percent
of all storm water, a decided benefit in a city where
the sewage system is often overwhelmed during
heavy downpours.
When Piano presented his first sketches to the
Academy, he described his idea for the roof by
asking his audience to imagine a huge elevated
swath of the park, with the museum tucked underneath it. Executing the concept, however, wasn’t
easy. One of Piano’s first demands was for an
assortment of plant species with a particular kind
of look: “He wanted it to be very monolithic, very
neat and clean and green,” says John Loomis, of
the SWA Group. But the plants that look good
together and the plants that thrive together are
not always one and the same. So Paul Kephart, of
Rana Creek, experimented with 29 different plants
before hitting on a selection that would promote
biodiversity as well as meet Piano’s aesthetic
Plants were grown on innovative trays made
from coconut-husk fiber (bottom photo)
and then laid on the roof like tiles (middle).
Once the trays degrade, they will leave
behind a lush carpet of vegetation.
Francisco’s topography, and is blanketed with nine
native plant species, which were chosen for their
ability to attract pollinating creatures like bumblebees and hummingbirds, and butterflies such as
the threatened Bay checkerspot. Like other green
roofs, this one helps regulate temperature indoors
and out—though the urban-heat-island effect isn’t
a dire concern in San Francisco, where the mean
ROOF
ELEMENTS
GLASS ROOF
PIAZZA
OPERABLE
VENTILATION
SKYLIGHTS
ROOF TERRACE FOR
VISITOR ACCESS
GLASS CANOPY
WITH PV CELLS
The landscaping team devised a drainage
system using a 24-by-24-foot grid (above)
of gabions, wire baskets filled with lava
rock (below right). The gabions also provide
foot paths for maintenance crews hiking
up steep slopes (below).
Humus topsoil
Plant level
Growing medium
Filter sheet
Drainage layer
Weathering
Protection layer
Source rock
Waterproofing
Roof construction
LAYERED ROOF SYSTEM
Site plan, courtesy Renzo Piano Building Workshop; center right photo, Sarah Palmer;
bottom roof diagram, Erich Nagler; others, courtesy SWA Group
