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Case Study: A Practical Look at the Risks of Green Roofs

Recently, there have been a number of articles suggesting that the risks associated with green roofs have been overblown. Over the past few days, I’ve spent some time looking for more concrete examples of green roof-related risks in practice. I started by looking for case law where a plaintiff alleged an attractive nuisance claim against the owner of a building arising out of a green roof or other rooftop landscaping. Westlaw did not return any results entirely on point, but I did find a number of interesting attractive nuisance decisions which I may present in a subsequent post here at GRELJ.

The much more practical research that I turned up was the following except from an article by Kelly Luckett, the self-proclaimed “Green Roof Guy” who writes a column for greenroofs.com. In a column from the very end of 2008, Mr. Luckett describes how uneducated project teams may unwittingly expose themselves to unanticipated risks stemming from the maintenance requirements of green roof installations. His remarks also reflect a number of key points we’ve made consistently both here at GRELJ and over at gbNYC with respect to the additional risk management strategies demanded by new green building technologies and third-party certification programs.

It is also interesting to note that, for the particular project that he describes below, LEED certification requirements resulted in the green roof’s irrigation system being disconnected after the initial green roof establishment period, which resulted in a roof that did not appear as anticipated by the owner. One last important thought- Mr. Luckett hints that this project was located in Toronto, which, as you’ll recall, recently passed a green roof mandate. I think this is a great example of how legislation is fueling the types of liabilities that we grapple with here at GRELJ, and why, as always, contract language will remain paramount for green building project teams.

I would like to turn the focus now to an issue that continues to plague the green roof industry: the maintenance-free green roof myth.  Some in the media continue to espouse this nonexistent characteristic of green roofs resulting in many of our customers being painfully uneducated about realities of critical green roof maintenance!

Pretty strong language, I know, but the problem doesn’t seem to be getting better.  Let me tell you a story about my company’s largest project.  It’s a government owned project in the city that has become the nation’s green roof capitol; you know the place.  I sat in on a meeting where the general contractor, the architect, and the roofing contractor removed all mention of maintenance guidelines and the Plant Health Alert System from my submittal package!

For those of you outside the construction industry, a submittal package is a gathering of documents and drawings the subcontractor submits to the architect and owner to demonstrate compliance with the specifications for products or portions of the construction project.  When I questioned why they were removing critical pages of information from my submittals, I was told that they eliminated the irrigation system for this 96,000 square foot green roof based on a tour a green roof provider took the owner on during the preceding spring.  I asked if they had told them about the drought that killed green roof plants all over the region the summer before, to which I only received blank stares.  I practically had to threaten to hold my breath until I turned blue, or at least threaten to walk away from the project to get them to issue a change order to put the irrigation system back in.

The green roof was planted in June and July, 2007, and required routine irrigation throughout the establishment period, a task that could not be accomplished over 96,000 square feet using a garden hose.  After alleviating concerns over the irrigation system conflicting with LEED certification requirements by agreeing to disconnect the system after the establishment period, the change order was issued.  However, I insisted that the irrigation system remain in place as insurance should drought conditions require its activation to keep the $250,000 worth of plants alive.

Now fast forward two years. The phone rings; it’s the roofing contractor.  The ownership is requesting a walkthrough to discuss the condition of the green roof.  I asked our horticulturist to accompany me to the autumn meeting on the rooftop. We were greeted by the general contractor, the architect, the roofing contractor, and a clearly unhappy owner’s representative.  The condition of the green roof?  Starving sedums due to absence of the fertilizer that was supposed to have been applied the previous spring, per the maintenance guidelines that the ownership never got to see.

Also, since the plants did not receive the food required to grow and cover the surface of the growth media, the weeds moved in.  The good news –  the weeds will die over the winter and an application of fertilizer next spring will allow the plants to thrive.  The bad news – the project lost the opportunity for the plants to grow in one of the wettest growing seasons on record.  As you can imagine, there was a round of discussion about who was supposed to have provided the maintenance, a discussion that may wind up being continued in a court room.

However, the owner’s representative asked why the irrigation system was still there.  When the general contractor started to speak he was stopped by the owner’s representative who said the question was directed to me.  Before I could answer, another question was posed, “Do you tell your customers that they need to provide irrigation for their green roof?”  To which I replied, “Absolutely yes, every single one of them.”

The owner’s representative, clearly not expecting this answer, became even more agitated.  That’s when I began to appreciate how serious this problem has gotten for the green roof industry.  The owner’s representative placed in charge of one the city’s largest green roofs, in arguably the most green roof educated city in the nation, was utterly surprised by the fact that plants need food and water.  The building code issue evoked an urgent call to arms that brought about action by many and opened lines of communication among perceived adversaries, while lack of proper green roof maintenance poses far more serious threat to the green roof concept yet the green roof industry remains largely quiet.

Admittedly, nobody uses discussing maintenance during the green roof sale as their go-to closing strategy, but it’s a lot healthier for a green roof business in the long run to address this issue upfront rather than standing in the middle of a problem on a green roof facing an unhappy and uneducated customer the following season.  I’ll keep working on the code issues on behalf of the industry, but it’s time the industry start working on this much larger problem.

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8 Responses to Case Study: A Practical Look at the Risks of Green Roofs

  1. Mark Rabkin July 24, 2009 at 2:55 pm #

    Stephen,

    I have now read this entry 3 times. Thanks for your deep insight and research regarding the potential liabilities of green & vegetative roofs. I am working as hard as I can to help the insurance industry stand up and take notice of the issues at hand and the most effective ways to manage these emerging risks. If new building technologies such as vegetative roofs are able to achieve their expected benefits for reducing energy consumption and reducing storm water runoff, than the insurance community should be working to encourage best practices amongst the construction and development community to foster profitable growth and avoid potential claims. Failure to be proactive now will result in situations like the one you describe above hundreds of times over. In cities that are either encouraging or even mandating green roofs, the insurance community has the responsibility to monitor the construction and development teams to protect both their exposure as well as the public health and safety.

  2. Joseph July 29, 2009 at 1:55 am #

    Its not just the risks. I think you could better spend money on something like a geothermal system. It is practical and helps you go green without all of the headaches.

  3. Linda McIntyre July 29, 2009 at 3:49 pm #

    This is just common sense. An extensive green roof (in a temperate area)–with the right kind of growing medium and the right plant palette, usually hardy succulents, should not need irrigation after the establishment period.

    If a client wants something more like a roof garden, it is the responsiblity of the designer to make clear that this will entail more maintenance as well as a more complex system usually including irrigation.

    A green roof can be a practical solution in many cases–for stormwater management, for aesthetics/amenity space, for some saving on energy costs. But a green roof is not appropriate for every project, and no roof, including no green roof, is no-maintenance. If the owner will not commit to maintaining the green roof–maintenance on an extensive roof once plants are established should not be terribly difficult or expensive, but it should be done–then a green roof should not be part of the design.

  4. Jorg July 31, 2009 at 9:25 am #

    I can name 25+ projects like that and I did lot’s of study across America regarding this topic. I also like the comments.

    Since the green roof industry started in the North America I realized that many people in this business are just looking for the big and quick bucks. They come from all kind of professions and hardly have any fundamental and long-term practice with hands-on experience in landscaping plus horticulture.
    The ignorance of the North American people to well establish green roof guidance from Europe and the decades of green roof experience (more than 30 years) is an additional factor for many failures of American green roof projects.
    The problem starts with the designers/architects continues with consultants, suppliers, general contractors, subcontractors, building owners and closes with governments, cities, Unions and associations.
    The system in North America makes it very easy that – for example – a butcher, driving instructor, plumber, mechanic, student or just a talker etc. can get a sort of certification in green roofs consulting in less than 3 days. Sometimes it is even enough having some sort of plants related background or green history and you are accepted as a green roof expert. Another big bummer in America is that on each project there are too many people involved and too many want to say something. This drives the costs up and reduces the responsibility of a single person or company at the same time = nice breeding ground for failures.
    I am not complaining – I am taking advantages of the system, too.
    In this case and don’t listen since I am from Europe: If you do an extensive green roof in Toronto right -from the beginning- see above- you don’t need irrigation and waste your money. I also know from Europe that water is the most valuable resorce on earth and shouldn’t be wasted on green roofs.
    jbi

  5. construction management journals August 7, 2009 at 9:02 am #

    A green roof can be a practical solution in many cases–for stormwater management, for aesthetics/amenity space, for some saving on energy costs. But a green roof is not appropriate for every project, and no roof, including no green roof, is no-maintenance. If the owner will not commit to maintaining the green roof–maintenance on an extensive roof once plants are established should not be terribly difficult or expensive, but it should be done–then a green roof should not be part of the design.

  6. Andrew Michael Clements September 12, 2009 at 7:37 pm #

    The following article about a study by the Greek National Technical University concerning the thermal insulation properties of a green roof in Athens refers to a green roof which is for all intents and purposes maintenance-free.

    Greek Treasury Green Roof saves 5,630 euros in energy bills in one year.

    The “green roof” created on the roof the economy and finance ministry building in Syntagma Square has resulted in savings of 5,630 euros a year, the ministry announced on Tuesday. The savings arise from a reduction in power used for cooling, amounting to 3,600 euros a year, and a reduction in fuel used for heating by 2,030 euros a year.

    The green roof was created in July 2008 and covers about 650 square metres, or roughly half the surface at the top of the building.

    Measurements carried out by the applied thermodynamics laboratory at the National Technical University of Athens (NTUA) mechanical engineering department have shown that the difference in temperature between the areas of the roof with plants and those without are 18C, with the former reaching 37C and the latter 55C, respectively.

    The measurements also confirmed that the energy savings from the planting amount to 9.6 percent for cooling and 4.4 percent for heating. For the top floor of the building, especially, the energy costs for cooling can be more than halved.

    The finance ministry noted that the project was initiated to help improve the environment in central Athens, save energy and reduce the buildings operating costs, as well as acting as a model that might encourage initiatives by other private and public organisations.

    http://www.oikosteges.gr
    http://media.causes.com/ribbon/568189

  7. Jorg Breuning October 29, 2009 at 10:38 am #

    Andrew,
    I like your Greek project very much.
    Let’s discuss the maintenance issue in 10 years.
    Most projects in the US and at the beginning in Germany -25 years ago- had the same approach. However nature doesn’t care about human intents and purposes. Working with nature makes things much easier.

    Again, I keep you project on my list and we talk again.
    Jorg

  8. ... January 15, 2013 at 4:07 pm #

    Thank you for writing this article, I have been looking all over the web looking for the risks of green roofs and this was extremely helpful.

    Thanks,
    T.J.F.

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