American Society of Landscape Architects ASLA 2005 Professional Awards
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Plan of Roof Garden

View (looking north) of new addition to existing warehouse showing context of roof (photo: J.D. Peterson).
View of roof garden from roof to the west. Illustrates planting and undulating planters (photo: Jerry Harpur).
View from the loft showing the plexiglass screen, Trex paving, and custom planters. Photo was taken immediately after planting was installed (photo: J.D. Peterson).
Close-up of curved planter with succulents. Planters are tipped and sloped toward interior to maximize planting impact (photo: Holly Stewart).

Ivy Street Roof Garden, San Francisco, CA
Andrea Cochran Landscape Architecture, San Francisco, CA

"Turns the roof garden concept on its head . . . intriguing, elegant technical solution . . .done with incredible refinement and finesse. . . . incredibly personal. . . elevates landscape architecture to fine art."

— 2005 Professional Awards Jury Comments

Space for a 1,250 square foot roof garden was created in the renovation of this old warehouse into residential lofts in San Francisco. The penthouse was gutted to the walls and the roof terrace was planned off the penthouse space, over a modern addition to the older building. The architect and client asked the landscape architect to create a roof garden for the client that would be a visually harmonious extension of the interior space.

The client wanted to have a low maintenance garden for a quiet sunny reading place during the day, with a softness of planting to balance the industrial architecture. One important element that she requested was a fence to provide security and screening from an adjoining roof to the east.

To create an extension to the terrace with the materials used in the interior, the landscape architects designed the screen fence on the east side using sanded Plexiglass panels that allow the light to pass through and change throughout the day. The pieces are cut in trapezoidal shapes and bolted to a steel armature at different angles to diffuse the boundary and to allow the wind to flow through the fence. The different angles cast shadows and create an interesting patterned wall for privacy. On the other side of the roof deck, a cantilevered canopy made with the same material provides a cooler shade area during a summer afternoon.

To provide an interesting green foreground and create a sense of depth, the landscape architect designed a series of height-varied wavy aluminum planters parallel to the penthouse at the center of the terrace. Each wave is planted with a different genus of succulent. The different species display different tones of green and bloom brightly with red, yellow and orange flowers with each season.

The paving materials are elevated above the existing surface allowing the deck to be level with the drainage flowing below. The paving includes areas of checker plate aluminum, Trex (recycled wood decking), precast concrete pavers and Mexican river pebbles that are used to define different areas of the garden and to create extensions with the interior. The whole space is united by the dark gray tones of the pebbles. During the night, a fiber optic line glows under a narrow acrylic channel, conceptually extending out from the interior towards the city skyline.

Weight was a major factor in the design of this roof terrace. The engineering of the building below allowed only 80-lbs/square foot for the dead load on the roof. This restricted the height of the planters, the material selection for the planters, the soil mix (which in turn limited the plant selection) and the paving materials.

Another limiting factor in the design was the fire codes in San Francisco that minimize the square footage of both combustible materials and assembly area for fire exiting. Only 500 square feet of combustible materials are allowed. As a result the terrace is divided into three gathering areas connected by walkways surrounded by planters and pebbles that are not viewed as accessible.

To accommodate the weight versus combustibility and cost factors for the paving, three paving materials were selected and used in combination: checker plate aluminum cut into planks, pre-cast concrete pavers and Trex recycled lumber.

To address the weight and wind issues, plants that required more soil to grow well were minimized and pushed to the perimeter, closer to the structural walls and sheltered from the wind. Using succulents for the majority of the planting, allowed the designers to use a very lightweight soil. The height of the planting construction was elevated using lightweight aluminum sheet metal and Styrofoam blocks to keep the soil depth under 12 inches deep and weight to a minimum. The planting could endure the hot exposure and drying effects of the wind. The design of the screen also was based on the desire to work with the wind, allowing the current of air to flow through and be dissipated rather than acting as a sail that would require excessive support and engineering.

Access during construction was also a factor in the design. A crane was used once for budget reasons to bring materials to the roof. All other materials were brought up in the elevator and hand carried through the penthouse; therefore a modular system of construction that utilized smaller pieces was an integral part of the design.

After building a model for the screen and awning, the landscape architect consulted with a structural engineer on the structural details. The architect and fabricator also consulted with the landscape architects on the Plexiglass attachment detail to allow the screen to be fabricated in the most cost effective manner.


Close-up of screen with succulents below (photo: Holly Stewart).
Echeveria planting (photo: Holly Stewart).
View from east edge of roof looking back at canopy, loft, and planters (photo: Jerry Harpur).
Night view from interior. Fiberoptic lights extend the view toward the city lights (photo: J.D. Peterson).
View from south edge of roof looking back toward canopy and loft (photo: J.D. Peterson).
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