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Gardens In The Air04-01-02 | 161
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The roof deck hardscape was designed with interlocking brick pavers on a sand base.
 
Queen Palm

Syagrus romanzoffianum
King Alexander Palm

Archontophoenix alexandrae
Sea Grape

Coccoloba urifera
White Bird of Paradise

Strelitzia nicolai
 
 
Magnificent and intriguing, rooftop gardens have existed since ancient times. Although not new, roof gardens present many challenges to the modern-day Landscape Architect. Structural loads, soils, irrigation, climate conditions and access are all issues of great consequence. These issues demand innovative problem-solving resolution and bring to the forefront all the technical skills inherent in the profession of Landscape Architecture.
 
Situated on twelve acres of gulf-front property in Naples, FL, The Club Brittany brings the landscape to its residents in an innovative way. Developed by Gulf Bay Beach Development, Inc., this affluent 21-story resort-- an upscale Neapolitan enclave overlooking the Gulf of Mexico-- represents home to 127 residents. The community's main tower rests atop a five-acre parking garage which serves as an architectural pedestal, incorporates greater green space, and protects from the potentially severe winds. This pedestal gave birth to a roof garden theme and evolved into a total design concept for the project's landscape environment.
 
A system of "green spaces" were developed by J. Roland Lieber P.A. Landscape Architects (JRL, PA)-- a firm which has completed designs for six roof gardens in the Naples area, and has participated in numerous roof gardens throughout South Florida and Miami Beach-- to bring a feeling of "belonging" to the community. Several roof-top gardens were developed, varying from a central arrival area, to general circulation zones, to private area spaces. These gardens contribute to the overall concept of creating a green environment-- both to view and to experience.
 
To achieve this concept, the landscape design focused on two major perspectives. First, the JRL, PA design team--under the experienced direction of John Ribes-- wanted the gardens to be stimulating when viewed from above. The original idea consisted of a landscape montage, in which all of the "pieces" interlocked like a jigsaw puzzle to create a complete picture when viewed from above. In theory, all elements of the landscape, including plant materials, paving materials, structures and colors would blend to produce a focused picture; this evolved into bold, geometrical forms and color that produced the desired visual stimuli for the viewers above-- or the "bird's eye perspective." The second perspective addressed the sensory impacts desired for those within the space. Variety in scale-- through intricate walls and dense planting-- produced intimate garden spaces throughout the development.
 
Beneath the green environment lies a series of technical issues demanding a great attention to detail. Good drainage was imperative. Obviously a concrete foundation roof has no natural percolation capacity; a massive amount of water collects on the rooftop from surface run-off, vertical building sheet run-off and irrigation run-off. As an example, a one inch per hour rainstorm results in approximately 130,000 gallons of water per hour-- the equivalent of over 500,000 gallons in a 4-hour period. To accomplish the task of collecting, conducting and dispersing this immense amount of water, JRL, PA developed a four-layer drainage system, consisting of surface drains in the structural slab, surface drains at finish garden level, sub-surface and surface overflow planter drains and a perimeter scupper system. To move the water quickly, a shallow free-flowing river was created between the surface terrace deck and the structural slab. A floating wall system was incorporated along with state of the art drainage fabrics and waterproofing membranes.
 
Structural loads were also a challenge.. Concrete slabs require increased reinforcement, and columns are increased in size or spacing if possible. The simplest design structurally is achieved by placing trees directly above the columns. This solution produces a "grid" design often found in our urban centers which does not respond effectively to the landscape garden concept. The mere weight of soil is an issue. Soil weighs 3,000-4,000 pounds per cubic yard dry, a weight which doubles when wet. This equates to 100 pounds per square foot live load for a one-foot depth. To compensate for the weight, special soil mixes were used, along with filler materials such as polystyrene. Multi-level planters disguise the uniformity of a grid, and the variety of plant heights diminishes the sense of an artificial rooftop garden environment.
 
Wind is another major element that impacts roof gardens. High-rise buildings create a "wind tunnel" effect. And, when close to the gulf, salt air adds to the complexity. Plants must be salt and drought tolerant, and must be structurally capable of resisting the high winds. Stability concerns include "blow downs" (trees actually being felled by the wind) and "root retardation" (failure of roots to establish the normal support structure). Here, a substantial anchor system was specified to hold mature trees and palms upright and steady.
 
The roof deck hardscape was designed with interlocking brick pavers on a sand base. The deck was unique because the contractors had to install a drainage system between the structural roof deck and the finish surface. An elaborate "shallow river" channel through which water could flow quickly was also included. Due to the need of the uninterrupted flow of water through this "shallow river," the JRL, PA design team integrated the dry laid interlocking retaining wall system which requires no footing and floated above the "river."
 
For JRL, PA, the most difficult challenges for this project were design philosophy and construction related. Expanding the client's view of landscape beyond th concept of simple beautification and enhancement of the Gulf of Mexico vista was a challenge. Successfully, the design ultimately allowed the client to recognize the landscape as an interaction of aesthetica and function. Doria's Landscaping, Inc., the contractors, faced the challenge of flying in and installing the larger palms and trees in an area with minimum access with the assistance of large cranes and equipment. The strong winds from the gulf during the winter months created dangerous conditions during these cautious maneuvers. Roof garden design brings every talent of Landscape Architecture to the forefront. The art and science of the landscape architectural profession is really visible when one peels back the layers of the roof garden components. Perhaps, the principles inherent within the axiom, "An artist must intimately know his media to produce worthy art," cannot be more relative than when speaking of roof garden design. lasn
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