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


"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

Inspired by the above statement from the founder and developer of the Las Colinas commercial and residential development, which is internationally recognized as a model for master-planned communities, the design/build team at Complete Landsculpture set out to the remake The Gardens by the Mandalay in Irving, Texas, into a venue for the present and the future.



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Six thousand square feet of Thermory wood, which is ash (in this case) treated with heat and steam to remove all sugars and moisture thus making 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 has to be treated with a particular stain twice in two years at the cost of about $1 per square foot. 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 according to project coordinator Santosh George. Instead of a minimum of 6" of clearance from the ground to the walkway - for enough air circulation that the material doesn't heat up and warp - only a 4" gap was needed due to the wood's hardiness. The framing for the walkway and deck, which are ADA compliant, was made of high-grade cedar that has a 20-year warranty.


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The decorative walking surfaces are a material made of thermo-plastic rubber granules with a two-part urethane binder that was poured in place.


Background
Originally built in the 1970s, the project site is a rooftop garden set between two commercial building towers overlooking it. Very progressive for its time, it was 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 not providing an inviting outdoor experience.

The goal of the project was to improve and update the existing landscape and hardscape and to enhance the tenant experience and 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 own yard, and seamlessly tie the indoor and outdoor together. This included curvilinear surfaces of different materials; amenities such as an outdoor kitchen, fire pit, koi pond, an ornate fountain; and many creative seating elements.



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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" of each of the columns. On top of that is a 3" slab of the material. Then a wood frame clad with wood left over from the walkway and deck continues to the top. The woodwork took 2 days per column to complete. The covering is built with custom matrix panels framed with 6"x4" steel beams. Concrete Masonry Units (CMUs) veneered with the limestone comprise the fireplace and cook center structures whose countertops are also Lueders stone. Four fans and string lights were the final touches.


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Every five feet of the elevated walkway, weepholes were created 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.


Moving Forward
Santosh A George, ASLA, MLA, the senior landscape designer at Complete Landsculpture and the coordinator for this project, reports that the scope of their work included site analysis, recommendations for landscape improvements, concept and design development, budgeting, and finally the actual 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 simply covered by a wooden walkway and deck, synthetic turf and a 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. Their surfaces, and the cladding on pergola's columns, are Thermory wood, which is natural wood that has been thermally modified with heat and steam to enhance it, make it more durable and rot-resistant. 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.

And according to him, the six thousand square feet that was used in the project makes it one of the largest installations of the material in Texas. The cook 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 cladded with the treated wood.



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The old shrubs that were installed 30-40 years ago were removed along with the soil in the beds, which were then prepped with 6" of fresh soil and planted with new ground cover and shrubbery. However only one of the original trees, which was dead, needed to be replaced.


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In the water feature at the bottom of the photo, the 40-year-old, custom-built sculpture had been plumbed to be a fountain but because chlorine was being used to clean the water, the internal workings got damaged, making it dysfunctional. The decision was made 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 6 different types of lilies, two types of lotus and other water plants.


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

The project managers were Craig Chapman (softscape 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. (principle) and Payden Johnson (project manager) are credited with the structural engineering and load testing - Mike B. Davis, RPLS of Alpha Land Surveying, Inc. with the survey and layout of design.

Frisco Lumber Co. handled the woodwork, Adventure Play Systems installed the synthetic turf and rubberized surfacing, and United Metals was in charge of the pergola fabrication and installation.

Helping out 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 a koi pond and the outdoor furniture, which weighed up to 10,000 pounds.

George said that 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 to the existing storm basins. He also noted that laying out the curvilinear design as per the proposal and managing the execution of that brought its own demands. The sequencing of the various stages was also tricky as the first one to complete was softscaping, then the stonework and woodwork, and finally the synthetic turf and rubber surfaces.

The installation was completed in 90 days by a number of 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 final results were "well received and turned out exceeding everyone's expectations," states George. 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.

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



As seen in LC/DBM magazine, March 2018.






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October 15, 2018, 7:23 pm PDT

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