Landscape Architect Articles

Rooftop Garden Corporate Campus06-21-23 | Feature

Rooftop Garden Corporate Campus

The goal of the project was to improve and update the existing landscape and hardscape and enhance the tenant experience.
by Staff

This rooftop garden in Irving, Texas, received a thorough makeover by the Complete Landsculpture design/build team of Dallas. Due to load constraints, and to take advantage of the existing drainage, all the old hardscape and water features were retained. The flat surfaces were overlaid with a raised wooden walkway deck, 1"-thick synthetic turf, and 1/8"-thick rubberized material. The design/build project also included a pergola, cook center, fireplace, and fire pit.

Ben H. Carpenter was honored for his work to create the business and residential hub with a statue in Founder's Park in Irving, Texas. The grand opening was held on November 9, 2007.

In the water feature in the bottom of the photo, the 40-year-old, custom-built sculpture had been placed to be a fountain, but because chlorine was being used to clean the water, the internal workings got damaged, making it dysfunctional. The team decided to let it remain as a work of art and turn the basin, with help from an in-house pool specialist at Complete Landsculpture, into a koi pond with six different types of lilies, two types of lotus, and an array of other water plants.

This serpentine 4' elevated walkway connects all points of interest with the rooftop landscape.

Off the boardwalks, the decorative walking surfaces are a material made of thermo-plastic rubber granules with a two-part urethane binder.

Accent seating from Wausau Tile were specified as a focal point.

An aerial view of the landscape shows several mature trees preserved from the original planting. The old shrubs that were installed 30-40 years ago were removed along with the soil in the beds, which were then prepped with six inches of fresh soil and planted with new ground cover and shrubbery. However, only one of the original trees has been replaced.

The 'before' picture shows the preexisting pavers. A surveyor was hired to mark points every three feet to enable the curvilinear design to be exactly executed for the three materials used, namely synthetic grass, poured-in-place flecks, and the elevated thermal deck.

Weep holes (circle) were created every five feet of the elevated walkway in the direction of the slope so that all water that collects on the 38,000-square-foot area drains to the existing nine catch basins.

Inside the pergola's columns are steel posts on which the whole weight of the structure sits. Solid Lueders limestone, which is quarried in Texas, makes up the outside of the first 36 inches of each of the columns. On top of that is a 3" slab of the material. Then a wood frame clad, made of wood left over from the walkway and deck, continues to the top. The woodwork took two days per column to complete. The covering is built with custom matrix panels framed with 6"x4" steel beams. CMUs veneered with limestone comprise the fireplace and cook center structures whose countertops are also Lueders stone. Four fans and string lights were the final touches.

Six thousand square feet of thermally modified wood, which is ash (in this case) treated with heat and steam to remove all sugars and moisture to make it more durable, was used to create the walkway and the cook center's deck. The planks are not attached by nails but rather by clips on the frame. To retain its original brown color, it must be treated with a particular stain once, two years after placement. But it was agreed to forego it here, eliminating maintenance, and allowing it to "bleach" to a gray color, making for a nice contrast with the synthetic turf and the flex surfacing. Instead of a minimum of six inches of clearance from the ground to the walkway - for enough air circulation that non-treated wood wouldn't heat up and warp - only a 4" gap was needed due to the now-treated wood's hardiness. The framing for the walkway and deck, which are ADA-compliant, was made of high-grade cedar.

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"We are merely the custodians of this property during its important stage of development. None of us can take it with us into immortality, instead, remember that generations of others who will make Las Colinas their home (both business and personal) will follow us. Let them look back and reflect on the fine effort made by those who were its custodians during the development stage."
Ben H. Carpenter memo to his staff - June 1974

This statement by the founder and developer of the Las Colinas commercial and residential development, sets the tone for this internationally recognized design as a model for master-planned communities. The design/build team at Complete Landsculpture of Dallas, Texas, set out to redesign The Gardens by the Mandalay in Irving, Texas, and modernize the space. The mixed use complex is governed by the Las Colinas Association.

Background
In 1928, John W. Carpenter, Ben H. Carpenter's father, established a ranch in the area. By 1959, Hackberry Creek Ranch had grown to 6,000 acres and was eventually renamed El Ranchito de Las Colinas, or the little ranch of the hills. By the late 1960s, the westward growth of Dallas prompted the development of Las Colinas which took some 20 years to complete and included the Mandalay Canal, the Area Personal Transit system, a 50,000-resident community, and commercial campuses. The development was announced in 1973 as a joint venture of Southland Financial Corporation which was represented by corporate president, Ben H. Carpenter and chairman, Dan C. Williams, and its subsidiary, the Las Colinas Corporation. The Gardens by the Mandalay Tower project site was redesigned by Complete Landsculpture and finished in 2017. The project can be found between two commercial building towers.
The property was very progressive for its time, with its mostly paved surfaces and limited space for seating and engagement. The hardscape became dated, and the two water features were not performing to their fullest extent. Overall, the gardens, which can be seen by at least fifty percent of the surrounding offices, were no longer an inviting outdoor experience.

The Task
The goal of the project was to improve and update the existing landscape and hardscape and enhance the tenant experience. The redesign set to sophisticate the overall development of the garden while retaining the existing infrastructure. The client's vision was to create an outdoor living experience for all to enjoy, as if in their yard, and seamlessly tie the indoor and outdoor together, including curvilinear surfaces of different materials; amenities such as an outdoor kitchen, fire pit, koi pond, and ornate fountain; and many creative seating elements.

Moving Forward

Santosh A George, ASLA, MLA was the senior landscape designer at Complete Landsculpture and the coordinator for this project. The scope of their work included site analysis, recommendations for landscape improvements, concept and design development, budgeting, and the installation as project managers.

One of the most innovative aspects of the design and build was that the existing hardscape was not torn out, but instead, it was covered by a wooden walkway and deck, synthetic turf, and rubberized surfacing material.

"We pretty much put a thin layer on top of the existing surface without removing anything," George relates.

The walkway and deck were framed with cedar. The surface, and the cladding on the pergola's columns, are thermally modified wood, which is natural wood that has been modified with heat and steam to enhance it and remove all sugars and moisture, making it more durable and rot-resistant while also making it an ash color. The low oxygen content prevents it from burning while causing chemical changes. The 6,000 square feet of the material should be treated with a stain once every two years to maintain its color, or in this case, is left to age and create a gray contrast. And instead of nails, the boards are attached by clips.

"It's an ingenious system, and you see that it all looks continuous, and there are no nail marks on top of the deck," says George.

According to him, the 6,000 square feet that were designated in the project make it one of the largest installations of the cedar decking material in Texas. The cooking center, fireplace, and fire pit are veneered with Lueders limestone. The bases of the pergola's columns are solid Lueders stone, with the remaining portions consisting of wood frames clad with treated wood.

It Takes a Team
George complimented the craftsmen saying, "They did a fabulous job of merging it all to make it look seamless."

Challenges
Transporting all materials from the street level to the deck level was one of the biggest challenges, as was laying the synthetic turf, wood deck, and rubber surfacing in such a manner so that the stormwater will drain into the existing storm basins. Laying out the curvilinear design as per the proposal and managing its execution also stood out as a challenge for the design team. The sequencing of the various stages was also tricky as the first team to complete the project was softscaping, then the stonework and woodwork, and finally the synthetic turf and rubber surfaces.

The installation was completed in 90 days by several crews including eight for the softscape, five for the irrigation system, six for the hardscape, six for the woodworking, three for the metalworking, and six for the synthetic turf and rubber wet pour.

In the end, however, the results were well received and exceeded everyone's expectations. As evidence of the success of the project, leasing for the property went up from 65 percent to more than 80 percent.

The project won gold and silver honors from the Texas Nursery & Landscape Professionals, and a Merit Award from the National Association of Landscape Professionals (NALP).

The upshot of all this is an inviting place to be and enjoy, to hold informal office meetings or a celebration, or relax by oneself.

Team List
The Complete Landsculpture project managers were Craig Chapman (soft scape and irrigation), Dan Hall (water feature), Robey Canaday (landscape lighting and tree pruning), Jorge Burbano de Lara (commercial landscape manager/estimation), and Bram Franklin (planting design). Thornton Tomasetti, Nicolas Saenz, Ph.D., P.E., S.E. (principal), and Payden Johnson (project manager) are credited with the structural engineering and load testing. Mike B. Davis, RPLS of Alpha Land Surveying, Inc. helped with the survey and layout of the design.

Frisco Lumber Co. handled the woodwork, synthetic turf and rubberized surfacing companies oversaw the pergola fabrication and installation. Helping on the job were skid steers, mini skid steers, and mini excavators. Rented machinery included a Skytrack to move all the materials from street level to the deck level, and a 40-ton crane to move large boulders for the koi pond and the outdoor furniture, which weighed up to 10,000 pounds.