Landscape Architect Articles

Rooftop Rendezvous02-29-16 | Feature

Rooftop Rendezvous
TDH Landscaping, Baltimore

TDH Landscaping was called in to create a rooftop terrace for this five-story townhome overlooking the harbor in Baltimore. The 2'x2'x2" concrete pavers were installed using hand tools in a stacked bond pattern on pedestals (inset). One pedestal supports the intersection of four paver corners. There is no joint aggregate between the pavers, allowing water to directly enter the existing drainage system on the roof. The roof is slanted to allow for drainage, but the pavers are level, elevated anywhere from 3" to 5" above the surface of the roof. The homeowner provided their own outdoor furniture.

Manufactured fiberglass planters were placed on the perimeter edges of the terrace and planted with perennials including hydrangeas, iris, blue catmint, coreopsis and more. This perennial garden area was made of rooftop garden plastic trays. A small metal-framed concrete wall was built between the trays and the fiberglass to hide them. The concrete was finished with a colored stucco to match the existing walls, and then capped with granite. This area was built upon plywood instead of the heavy concrete pavers to lessen the weight. No anchoring was required to keep the planters in place – the size and combined heights do the trick. Additionally, nonbiodegradable packing peanuts were placed underneath the soil to elevate the space using a lighter substance. The irrigation system for the gardens runs on a timer and has a rain sensor. It gets shut off during the winter months to prevent damage from freezing temperatures. The system has worked flawlessly so far, according to TDH.

The biggest challenge was getting the materials up to the roof. The townhome is in a five-story building with a spiral staircase, and TDH wanted to minimize the materials brought inside the home and up the stairs. They rented a crane from Coastal Crane Service to move the materials from ground level to work level. The logistics of operating it in the small space proved challenging as well: since the crane blocks the street, arrangements had to be made with the client as well as their neighbors to make sure materials were being moved at times that were convenient for everyone.

The owner of this five-story townhome located in Baltimore's Patapsco River Harbor wanted a rooftop terrace garden and outdoor living area. The space was to include an outdoor kitchen and dining area, vegetable and perennial gardens, and a Moroccan inspired fountain feature, all overlooking the harbor. TDH Landscaping created a paved rooftop paradise that met the client's needs and, with much ingenuity, followed regulations for weight limits on the roof.

The Process
After meeting with the client to determine their desires, Nathan Boliek, sales manager for TDH and the designer for this project, considered three factors in designing the rooftop space: first, what the client wanted; second, what the site required; and third, the dwelling itself. For this project, the specific elements to be considered in terms of the site and the dwelling were weight limitations due to being on a roof and the appearance of the building. With these factors in mind, TDH put together a computer rendering that included all existing on-site structures. The design was created from there based on the client's desires and the limitations of the space.

The rooftop terrace was designed to keep circulation open. The perimeter is lined with fiberglass planters that include perennials, trees and shrubs, and a vegetable garden. The outdoor kitchen serves as a border to the roof as well. The fountain feature is a focal point with seating around it to overlook the harbor.

Getting the materials up to the roof proved to be the biggest challenge for TDH Landscaping. The townhome is five stories and has only a spiral staircase, so the company elected to not move anything inside the house. Instead, they contracted out Coastal Crane Service to lift the materials up to the roof. Using the crane was the primary challenge; the logistics of operating the crane in the neighborhood was the secondary challenge. The street is wide enough for two standard vehicles or one crane, so TDH had to coordinate with the clients and their neighbors to make sure it was only running when it would not inhibit the flow of traffic.

Once the materials were on the roof, installation could begin. The pavers, water feature and outdoor kitchen were all installed using hand tools. To not interfere with the roof's existing drainage system, the pavers were set on plastic pedestals. The roof is slightly slanted, but the pavers are level, elevated anywhere from 3" to 5" above the surface of the roof. There is no joint aggregate: water goes directly between the pavers to the drainage system.

The fountain feature was built out of concrete board with metal framing. Moroccan inspired tiles and glass beads complete the desired look.

The outdoor kitchen area includes a homeowner-provided grill, storage space, a small refrigerator, and a built-in trash receptacle. The granite backsplash was made to be 2' tall instead of the standard 6". The added height allows it to double as a screen for two air conditioning units, and creates extra storage. The kitchen area was also placed on plywood instead of concrete pavers to decrease the weight.

One feature that was non-negotiable to the homeowner was the fountain. Built by TDH from concrete board with a metal framing, the structure measures 4'x4' on the interior and 5'x5' on the exterior. Being on a roof, some weight restrictions had to be put in place. To keep from exceeding the maximum allowed weight, the square structure is built on a base of vinyl plastic plywood instead of the 100-pound concrete pavers. Additionally, the water level was decreased from 18" to 12", reducing the volume of water and therefore the overall weight of the feature.

Weighing the Options
Being on the roof of a five-story building, this project required that accommodations be made so as not to exceed the weight limits put in place by engineers.

Instead of using concrete tiles underneath the water feature and the outdoor kitchen, TDH used a plastic vinyl plywood to support them. This reduced the weight virtually to just that of the structures.

In the planting areas, in addition to the use of plywood instead of tiles, nonbiodegradable packing peanuts were placed underneath the topsoil. Packing peanuts decrease the weight in the planter, and their loose placement allows water to filter through. It was important to use nonbiodegradable peanuts, since biodegradable packing peanuts made of cornstarch will dissolve once wet. The size of the water feature was non-negotiable for the client, but its weight was a concern. To bring down the weight without compromising the size of the feature, the water level was reduced from 18" to 12". The change in water volume decreased the weight enough that the installation could proceed.

The Final Product
Entering the rooftop terrace from the home leads first to the outdoor dining area with homeowner-provided patio furniture. A retractable awning supplies shade for this space. Across from the dining area, the fountain feature is surrounded by brightly colored seating so the homeowner and guests can enjoy the harbor view.

The outdoor kitchen area includes a grill, storage cabinetry and drawers, and a built-in trash receptacle. The granite countertop has a 2' tall backsplash instead of the standard 6" backsplash. This allows it to screen two air conditioning units from view while creating additional storage.

Fiberglass planters surround the perimeter of the terrace area, including two that are designated for the homeowner's vegetable garden. The plants, from TDH Nurseries, include endless summer hydrangeas, iris, two Japanese red maples and more. Plant materials were selected to create extended bloom and to contrast with the neutral building. The Japanese maples are the only plant chosen that may not be permanent: this is because their roots will eventually grow larger than the roof space can accommodate. Fortunately, TDH has a maintenance contract with this client, and they will trim back the root growth to make the trees last longer. The planters have an irrigation system on a timer with a rain sensor, and so far it has worked flawlessly, according to TDH. In the winter, the system is shut off to prevent damage from freezing temperatures.

At any given point, there were three to four members of the TDH team working on the project. It took four months overall, including some delays due to weather and availability of the materials.