New York's Cooperative and Condominium Community

Habitat Magazine October 2020 free digital issue



Flower Power: Roof Gardens

After the board members of the 600-unit Churchill at 300 East 40th Street had completed a major renovation of their building several years ago, the members began looking around for other ways to enhance the building. Wouldn't it be nice, they mused, to put some plantings around the roof deck on the 34th floor...soften the edges with shade trees and flowers? Given all the other projects the board had completed successfully, how hard could it be? It was just a matter of buying some plants, installing planters, reminding the building staff to water every day, and voila, another enhancement for the shareholders of the luxury co-op, right?


"We thought we could do it without the intervention of someone else, and you know what, it's not easily done," says the treasurer, Robert Stella, with a trace of chagrin. The expectation, says Stella, was that the board would be able to purchase some plantings, put them around the deck, and turn over the day-to-day maintenance to the building staff. But the staff, already caring for 18,000 square feet of plants on the first floor, sometimes didn't make it up to the roof deck for days. The end result was that the garden, installed in the summer of 2002, was barely getting by at the end of 2003.

The hardest part for the board members was that the seasoned group of professionals had made a rookie mistake - they didn't do their homework. They had invested their time and the building's money in a project without proper research, and a planned amenity quite literally withered on the vine.

For a board on a quest to enhance its building, creating a roof garden can be the smart way to go. Done right, it puts a scent in the air and improves the value of the property. Done wrong, it presents a Pandora's box of problems. But there are ways to build - and maintain - that sweet smell of success.

Know Your Neighbor

Landscape designers and architects who have labored in the vineyards of garden design say that the story of the would-be garden at the Churchill is familiar. The most common mistake is that boards do not approach the roof garden as a serious capital investment and don't spend the time necessary to see the project through.

"It's no different than redoing the lobby or the façade or repointing the masonry," says Signe Nielsen, a principal of Matthew Nielsen Landscape Architects. Boards need to be prepared to invest a greater than normal amount of time in planning a roof garden; whether it thrives or fails, the landscape architect points out, "everyone is impacted, if only because their money is going into it."

Before boards go to work, they first need to find out who may be opposed to the project. This is crucial, say property managers and landscape designers who have survived the trench warfare of co-op infighting, because a vocal minority can hold up a project for months, if not years, with complaints about access, use, and noise.

"Boards definitely have to be creative in the way they work, and feel out who might cause a problem and talk to them before it becomes public. This is critical," says Nielsen. In particular, the board should be reaching out to shareholders who live just below or adjacent to the roof, and listen to whatever concerns those residents may have - either about the state of the roof, or what it would be like, with people sharing their view or walking overhead. The president should call the unit-owners most directly affected in advance and tell them what the board is considering and ask them whether they have any questions or concerns.

That was the tack that the board members at the Bolivar, a co-op at 230 Central Park West, took when they decided to add a roof garden, and the early outreach efforts made all the difference. After talking to the shareholders who lived on the top floor, the board learned that the history of leaks from the roof had been more extensive than they remembered, and that one shareholder in particular was very concerned about the potential noise of residents walking overhead. After listening to the concerns of the shareholders on the top floor, the board then presented the idea to everyone.

And, true to form, nearly everyone had an opinion. Some shareholders didn't want the building's reserve fund spent on the endeavor. Others wanted to know who would be using it. Still others pointed out that since they were living in a luxury co-op, people who wanted to garden could buy a house in the country and indulge their green thumbs in their own backyards.

But the directors held firm, insisted the project was going forward, and had their own facts marshaled in defense. First, they pointed out, the garden would be a financial enhancement. Private terraces alone added about 10 percent of value to individual units, so a roof garden would increase the value of the whole building. Then there was the issue of enhancing the building's place on Central Park: why not create a deck with a view to give shareholders a place to bring guests to enjoy the sights of the city? Finally, the board members observed, they were empowered to improve the building as they saw fit. After renovating the roof to answer concerns about the noise and potential leaks, the board went ahead and installed the garden, an amenity that, according to reports, remains the building's crowning achievement.

When it comes to dealing with shareholders, board members need to be prepared to answer the question, what value will be added to the building, who will use it and what will be the rules of being on the roof? "An aesthetic argument is never going to carry the day," warns Nielsen. "It's always about dollars or about maintenance or potential problems. Those are always the issues."

Committee, Committee

One way to defuse a potential conflict is to invite one or two of the most vocal shareholders to sit on the garden committee, with the caveat that that the board has the final say over the design and the schedule for installation.

Keep the committee small. The more people involved, the harder it is to do something nice, warns Saskia Cacanindin, a landscape designer with Town & Garden, a landscape design and construction firm. With larger groups, she explains, "Good ideas get watered down."

Neil Davidowitz, president of Orsid Realty, agrees. "Different people have different perceptions of what a roof garden should be," points out Davidowitz, who teaches a class with Nielsen each year at the annual conference of the Council of New York Cooperatives & Condominiums on roof gardens. If there are more than four or five people vetting ideas, "it starts to get problematic."

After the committee is assembled, its first job is to meet with a building engineer or architect to determine the structural integrity of the roof, and whether there will have to be additional construction, to raise or secure the parapets, or ensure that the roofing membrane is watertight. Then, the committee needs to locate the company that has guaranteed the roof, and find out whether a garden can be included in the warranty.

"More often than not, people make changes on the roof, never tell the manufacturer, and then that warranty becomes void because the manufacturer wasn't brought into the loop," warns Tony Colheo, president of Flag Waterproofing, a roofing contractor. "If you call the manufacturers, let them do the necessary inspections and install the right products, they will include that work in the warranty."

If the roof gets a clean bill of health from the engineer, then the committee's next step is the fun part, conceptualizing what they want on the roof. Think about it in terms of space and access, say architects who have worked with co-ops and condos on roof gardens. Will it be a place of passive recreation - reading or sunbathing - or will there be an area for entertainment? Will there be lights? Will music be allowed? What about tables and chairs? "How do they envision it being used?" asks Steven Zirinsky, a principal of Zirinsky & Cox Architects. "How much room are we talking about here? How are you going to have it policed? How are you going to access it?"

When the process of trying to plan and design a garden for their co-op became too overwhelming for the board members at the 100-unit co-op at 420 Riverside Drive, Zirinsky's partner, Fred Cox, borrowed a trick from a landscape designer he knew. Put down a blanket and imagine that is the space they would have to design around, Cox suggested to the board members. Now, given that limited space, what did they want to see on it?

The technique worked. The board, which had been stymied about the size of the garden, its intended use, and the types of flowers and furniture, pared down their ideas to the fundamentals and decided to go with a minimalist look while they tested shareholder reactions. Robert Rodriguez, the president, reports that the board is quite pleased with the garden, which opened last summer.

"We did cement pavers - that's the flooring - and we have six planters up there. There is one good-sized table and about 10 chairs, and a few reclining chairs. And we are adding more. We are also adding some lights so shareholders in the evening can see where they are going." There is a security panel on the door to the roof, with a code, so only residents with the code can access the roof, and a list of rules on using the roof garden. The driving philosophy of the rules: don't litter, don't disturb your neighbor. "Some people use it all the time. Some people don't," reports the Rodriguez. "I think in some ways it's still a work in progress."

Grow Your Budget

When the shareholders of the 110-unit co-op at 50 East 10th Street started their garden nearly 30 years ago, the board gave the shareholders some starting money but left the maintenance up to the volunteers. With a dedicated troop of amateur gardeners, the shareholders started out with a few flowerbeds and potted plants and, along the way, expanded their small garden into a horticulturist's dream. Today, there are wisteria, dogwood and birch trees, irises, azalea bushes, hydrangeas, Black-Eyed Susans, peonies, and chrysanthemums. There are four climbing rose bushes and several different clematis vines on trellises, two dwarf red maple trees, a flowering crabapple tree, and a Japanese snow bell.

But you can't, as the old saying goes, get from here to there, not right away. If the board is not willing to foot a big bill for flowers, "you can't instantaneously have what we have now," points out Patricia Bartels, a resident at East 10th Street and the self-acknowledged "enlightened despot" of the co-op's garden committee. Even if the board was willing to foot the bill for the roof garden, trees get sick, plants die. The best idea is to think about a roof garden in terms of a five-year plan, she suggests. What can you handle now, and how would you like to see it grow?

The most important part of preparing a budget is to start small, and plan for ongoing maintenance. Designers maintain that despite the best intentions, a volunteer team of caretakers is not going to last in most co-ops or condos. Think about what you want to spend and then plan accordingly.

If the board just "wants four nice big planters and four nice trees, it's not going to cost $15,000, but if they want a whole landscape installation, there should be an adequate budget," observes Cacanindin. That can mean pushing the budget upwards of $30,000 to $40,000, and more. At 132 West 22nd Street, "we did some woodwork, a pergola, screened the water tower with lattice and a planter, and put a bridge over some steel beams. We had birch trees, dogwood trees, lots of vines, wisteria, smoke bushes, pine trees, grasses, roses, and some other shrubs and summer flowers," recalls the designer. Her firm also installed an irrigation system and lights, for using the deck at night. The entire cost was about $30,000. It is not uncommon for the price tag, to run upwards of $100,000, depending on the extent of the installation and the supporting architecture (including pavers, an irrigation system, lighting, and patio furniture).

The best way to keep the process in hand is to create a budget and stick to it. The committee should know how much it has to spend, and communicate that budget to the designer. And don't be afraid to vet the professionals. Ask a designer to show portfolios and references. Be sure the designer can work with the board, that he or she has experience on rooftops, which is very specialized work, and find out whether the projects have been successfully completed on budget.

Once the budget and design have been hammered out, a landscape designer will submit a rendering to the committee who will then submit it to the board. "It is very important that everyone looks at the plan before it is installed," says Alec Gunn, an architect and principal of Gunn Landscapes. "Make sure everyone sees the plan and is comfortable with it."

Gunn recommends that the board take the extra step and put the rendering in the lobby and, if necessary, make a full presentation to the shareholders. That may not be practical in large buildings, with hundreds or thousands of unit-owners, but the more communication there is up front with the residents about the project, the fewer arguments over the final installation down the line. And a word to the wise, offers Kari Katzander, a landscape designer and principal in the design firm Mingo Design: if a board is willing to pay up front for the presentation, with photos, and different types of grasses and renderings, the project will probably sail more smoothly with the other shareholders. "The more color, the more pictures, the better it's going to be," says Katzander.

Construction Junction

While the design process can take anywhere from two months to a year, depending on how quickly or slowly decisions are made, the installation process, once begun, depending on how involved it gets, can take from a handful of days to a month or more. Before the installation starts, the committee members should alert the board members on the top floors that workers will be moving around in the building, using the freight elevator, or the stairs to the roof. It may not involve the same kind of material that a hallway renovation requires, but installing a garden, even if it's only planters and flowerbeds "does involve a certain amount of noise and mess," points out Gunn. When the workers are using the service elevator, it will be tied up during the installation. One way to circumvent some of the work site atmosphere is to ask the firm to build as much of the installation off site as it can, recommends the landscape architect.

Maintaining the garden after it's installed should be part of your planning. Boards should sign a maintenance contract, which can run from $200 to $400 a month, so there is a professional coming regularly to check on the irrigation system, make sure the plants are fertilized, and trim and prune the shrubs and trees.

"This is really, really an issue for me," says Davidowitz. "I think it's a huge mistake to solely rely on individual volunteers to maintain the project. I am a firm believer that you need a company to do ongoing maintenance if you are going to sustain the project. I've seen projects where you rely on the volunteers and they move away. Within a year or two, the $100,000 you've spent to create this fabulous garden is [wasted], because [the garden] hasn't been maintained."

Done right and maintained properly, there is no argument against a roof garden. Not only will it add value to the building but it also provides a "wonderful quality-of-life component for a building," observes Davidowitz. Peter Livingston, president of the board at 50 East 10th Street, agrees. For Livingston, the key to the garden is the emotional nexus it provides for the life of the building. His co-op's garden - which has been the backdrop for weddings and has been featured in the New York Times - offers shareholders a quiet oasis in the middle of the city and a chance to connect with nature in ways that they can't easily do anymore. In the mornings, people can bring up a cup of coffee, sit and read the paper, or look out over the city. In the evenings, after work, they can indulge a green-thumb urge, entertain guests, or just sit on the roof, sip some wine, and enjoy the view. Even people who never use the garden bring friends from out of town up to see it.

As for the shareholders who do use it, Livingston notes: "A lot of people just want to be gardeners, and they don't have the opportunity. They don't have a summer home. They have a yearning to see something grow and to enjoy it. It's perfect for them."

Sidebar: A Green Roof Grows in Brooklyn

For the truly adventurous, there's a whole other dimension to putting a garden on your roof. Instead of installing planters and trellises, you can go the extra mile and plant flowers right on the roof.

It's called building a green roof, or "eco-roof," and the wave has caught on over the past five years, since the U.S. General Services Administration began encouraging such construction as a way to promote environmentally friendly buildings.

While there are several ways to build a green roof, the most common method is to lay down a drainage mat, cover the mat with a lattice-like plywood, mount a soil substrate over the plywood - a soil mix of shale, sand, and dirt - and then transplant a hardy mountain type of plant commonly known as "sedum."

The benefits of building a green roof are manifold, points out Sarah Wayland-Smith, a designer with Balmori Associates, a landscape architect firm building a green roof in Long Island City. The grass covering not only insulates the building in the winter and cools it in the summer, but it also reduces storm water run-off into a city's sewer system. In addition, the green roof, which protects the surface from ultraviolet rays, "will double the life span of the roof," points out Wayland-Smith.

Ed Snodgrass, proprietor of Emory Knoll Farms in Street, Maryland, and a leading provider of green roof plants and installation materials, agrees. "Green roofs combine form and function like few other amenities on the building." While it can be twice as expensive as simply redoing a roof, "in a longitudinal sense, the extended membrane life will pay for the green roof itself."

Building an environmentally friendly building was the main reason Benton Brown and Susan Boyle, a husband-and-wife on contracting team in Brooklyn, decided to install a green roof on their apartment house in Crown Heights last year. The couple, who purchased the Dean Street building two years ago, learned about green roofs from Emory Knoll Farms' Snodgrass and from Earth Pledge Foundation, a New York City organization dedicated to promoting sustainable development. After attending several seminars and researching information on the web, the couple decided to install an "extensive" roof garden - a (relatively) lightweight garden that will support plants that can live in an arid, windy environment. A second form of green roof, known as "intensive", uses more soil and can sustain shrubs and trees. It also puts considerably more weight on the roof.

First, to protect the roof membrane from accidental tears or leakages, the couple laid down a drainage mat over the area where they wanted to build the garden. Then they laid down a plywood base for the soil, a substrate mix of shale, sand, and dirt. That was about two inches thick, says Boyle. Then the couple transplanted sedum, which can survive with little water in an arid environment. While one portion of the garden, installed on a sloping portion of the roof, is strictly for viewing only, the second, smaller garden, is designed to be walked on, "once the plants are established," explains Boyle.

Because a green roof, either extensive or intensive, can add significant weight to a building, most architects and contractors recommend that homeowners install a green roof only when the entire roof needs to be renovated. "It made more sense [to do a green roof], because we needed a new roof anyway," says Boyle, who estimates the entire roofing job, including the installation of the green roof, cost $15 per square foot, or $33,500.

For more information, check out or e-mail Ed Snodgrass with questions at Other websites, include and, a national website of green roof contractors.

Sidebar: Roof Garden costs

When it comes to designing, planning and maintaining a roof garden, the more boards know about the costs up front, the more they will be able to plan for the kind of installment they want. But be warned, there is always "massive sticker shock," says landscape architect Signe Nielsen. According to Nielsen, who recently published a book on roof top gardens - Sky Gardens: Rooftops, Terraces and Balconies (Schiffer Books) - the cost of building a roof garden is always more expensive compared to what the board thinks it is going to be. One way to ease pain, she maintains, is to remind residents that individual garden terraces can increase the overall value of that apartment by upwards of 10 percent.

The following figures were composed with the assistance of roof garden architects and designers. Figures are rough estimates and can vary up or down, according to the level of work detail and whether a landscape architect or landscape designer is performing work. If the co-op purchases and installs planters, flowers, and deck furniture that can also mitigate costs.



• Site visit, initial client meeting, preliminary plan: $2,000.

• Schematic design alternatives/cost estimate: $4,000

• Presentation drawing/rendering: $2,000-$2,500.

• Preparing/filing construction documents: roughly 15 percent to 20 percent of the construction cost.

• Construction administration: usually hourly service, or 20 percent of total construction costs.


A garden terrace that is 20 feet by 10 feet will cost about $15,000. The following is a breakdown by materials:

• Pavement system: $15 to $25 per square foot. This includes tiles, concrete pedestal or bluestone pavers. Granite or other stone pavers, or lightweight pavers are more.

• Wood decking: $25 to $35 per square foot.

• Planters: wooden, lined with sheet metal, cost about $125 per linear foot.

• Plants, flowers: trees cost $400 to $500, depending on size and type; perennials, ground cover or ornamental grasses: $15 to $20 a bunch. Small evergreens or flowering shrubs, $35 apiece. Vines, depending on size, $25 to $50 each.

• Irrigation: $1,500 to $13,000, depending on whether electric and water supply exist already.

• Lighting: depends on what electricity is supplied already to the roof, can range widely, $2,500 to $20,000.

• Deck furniture: ranges widely, depending on whether co-op purchases or has contractor purchase. If contractor purchases, four feet diameter table and four chairs runs about $2,500; chaise lounge about $1,500.


• Monthly contracts: $200 to $1,000 a month. The cost is based on a time and materials estimate and includes tasks such as pruning, weeding, fertilizing, maintaining the irrigation system, checking drains, sweeping, and planting seasonal flowers.


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