Having explored the many benefits of installing a green roof, now we’ll explore some of the complications, expenses and long-term commitments when you choose to turn an ugly, underused part of a building’s real estate into a major asset.

Green roofs are a costly undertaking as you can’t simply buy some plants, put them in pots on your roof and call it a garden. You’ll need to know your building’s load capacity; usage (will it only be viewed or be used as garden space?); what part of the roof you will green (exposures will vary greatly); whether to install an intensive green roof which is thicker, deeper, heavier and supports more plants, but requires more maintenance; or extensive which is shallower, lighter and more minimal maintenance; whether you opt for a modular vegetated roof, an alternative to the built-in roof where mobility makes it easier to do roof repairs and is quicker to achieve completion (but costs somewhat more); what plants will be used; and what systems will be used for root barrier, drainage and irrigation.

We hope we haven’t lost you yet because the ROI can be extraordinary which is one of the reasons green roofs and private gardens are also exploding on the residential front.

You are going to need a professional engineer and registered architect to do a structural analysis to determine if your roof can sustain vegetation or needs reinforcement; an architect/landscape designer and/or green roof specialist to design and install the system; and a big budget.
A decision will also need to made on the type of planting and systems to be used – from relatively simple sedum and grasses to a veritable forest – that fit your budget, climate, facility and goals. The latest trend is to go with native plantings.

The Mayor’s Office on Sustainability offers a green roof tax abatement. In 2008, New York City and State passed legislation – now available through March 15, 2018 – of $4.50 per square foot (up to $100,000 or the building’s tax liability, whichever is less). To qualify, your installation must be at least 50% of rooftop space.

Some prominent buildings in NYC that have installed green roofs include Rockefeller Center; the Empire State Building; Javits Center; Brooklyn Academy of Music; the Parks Department’s Five Borough Administrative Building on Randalls Island; Zeckendorf Towers on Union Square; the rooftop farm at the Brooklyn Navy Yard; the New School’s LEED-Gold student center; and the Bronx County Courthouse, the first of its kind in the borough.

The largest green roof in New York City is in midtown Manhattan atop the U.S. Postal Service’s Morgan Processing and Distribution Center.

The funkiest – and award-winning – green roof includes plastic rocks, artificial boxwoods, clear crushed glass and recycled rubber mulch. It’s on top of the Museum of Modern Art and, although visible, it’s inaccessible.

Among the latest news is Macy’s interest in creating a rooftop restaurant and garden at Herald Square; the green wall at the top of The Knickerbocker Hotel; and, though we know it’s not the roof although it’s green, the renovation of the glass pyramid Apple store uptown which is expected to include a grove of potted trees.

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Steven_J._SchleiderBy Steven J. Schleider, MAI, LEED-AP BD + C President, Metropolitan Valuation Services

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