Green Roofs - Living Architecture Monitor - Summer 2009 - (Page 6)

BEST PRACTICE PART 1 OF 2 RISK-REDUCTION TOOLS LEARNING TO MANAGE THE POTENTIAL RISKS OF GREEN ROOF DESIGN, CONSTRUCTION AND INSTALLATION By Heather Stevenson and Dan Slone onstruction disputes have been around since the first yurt collapsed and over time, a substantial body of law has developed to deal with construction problems, including roof failures and associated liabilities. Why would a “green roof” be associated with more liability than a conventional roof? A conventional roof has to keep the rain out, hold up for a reasonable number of years, possess certain properties in a fire and withstand predictable weather conditions like wind. A green roof must do all of these things, plus it must maintain a living component through a normal variation of weather conditions, maintain its functions during these variations (insurers have raised questions about the fire risks of some roofs in drought conditions), deal with increased weight on the roof, address potential root intrusion into protective membranes, all while performing one or more advertised functions: storing large amounts of water, treating water to remove various pollutants, providing aesthetic space for social functions, supporting urban agriculture, reducing building energy use and urban heat island effects and/or providing habitat. The green roof may also stimulate human activities such as parties, gatherings or recreation that might not occur on a conventional roof. A limited range of installers would be called upon for conventional roofs and these have a developed set of risk-management tools relating to installation practices, as well as insurance and contract provisions to control and appropriately allocate risk. Green roofs often require the services of additional professionals, each of whom may be able to optimize the roof for certain functions, but not others and any of whom may work by themselves or with other professionals. Practices, insurance, contracts and risk allocation may not be in alignment. A real-life example of the challenges which may be associated with green roof construction may help highlight the unexpected and complex liability problems that can to crop up. A developer of a mixed-use development in the Southeast United States created residential units with green roofs. The waterproof liner for the roofs was made by a German company and the warranty, written only in German, was difficult to obtain. The developer hired a builder to build the residential units, a roofer to install the waterproof liners, and a landscape designer and contractor to install C LOOK FOR PART 2 OF THIS ARTICLE IN THE FALL 2009 ISSUE OF THE LIVING ARCHITECTURE MONITOR (LAM). GET YOUR OWN COPY OF THE LAM TODAY BY BECOMING A MEMBER OF OUR FAST-GROWING GREEN ROOF AND WALL COMMUNITY AT WWW.GREENROOFS.ORG the plants on the roofs. The developer entered into purchase and sale agreements with new owners in which the developer made a complete 20year guarantee for the roofs. After a particularly strong seasonal storm, several of the green roofs were damaged by wind and the roofs leaked. Prospective purchasers, concerned about the leaks, clamored for copies of the liner warranty, and when the copies were not readily available, they refused to close on units. Other existing owners demanded that the developer fix the leaks. The developer claimed that the roofer was responsible and the roofer claimed that the landscape company was responsible because that company’s workers had made holes in the waterproof liner. Unfortunately, the purchase and sale contract had been written in such a way that the developer had guaranteed the roofs for 20 years against any failure whatsoever, in much the same way as he had guaranteed his conventional roofs for years. So, the developer had to fix the roofs and then try to recoup his expenses from the roofer, the liner manufacturer or landscape company. What could the developer have done differently? This article – the first of a two-part series – is designed to give the reader a brief introduction to some of the risk-reduction tools that the various players in the green roof industry can use to address risk in the design, construction and installation of green roofs. This issue has some urgency in light of the national discussion of liability associated with the “green” aspects of new construction. While much of this conversation has resulted in the green issues being viewed as normal construction issues, green roofs, rightly or wrongly, have been identified by some as having larger and more frequent liability issues. The construction of a green roof is a more collaborative process than the construction of a conventional roof. Green roof design, construction and maintenance can involve not only building owners, architects, engineers, general contractors and roofing contractors, but roofing consultants, landscape designers or landscape architects, landscape contractors, landscape maintenance contractors and nursery staff to provide appropriate plant materials. The lead individual or company on a green roof project can vary from the architect to the roofing contractor to the landscape designer or system manufacturer. The activities of each of the specialists involved in green roof design, installation and maintenance have the potential to adversely affect the integrity of the roof, resulting in leaks, dead or dying plants. With all the liability faced by each of the construction parties, one may wonder how are green roofs ever built? In large part, “riskshifting” makes green roofs possible. Risk can be defined as: Magnitude of Harm x Likelihood of Occurrence Ability to Shift Risk http://WWW.GREENROOFS.ORG

Table of Contents for the Digital Edition of Green Roofs - Living Architecture Monitor - Summer 2009

Green Roofs - Living Architecture Monitor - Summer 2009
The Case for Mandated Green Roofs
Student Sustainable Design Competition
GIF Road Show
U.S. Green Roof Industry Grew By 35 Percent in 2008
Part 1 of 2: Risk-Reduction Tools
On the Roof With . . .
The World's First Accredited Green Roof Professionals (GRPs)
A Haven for Butterflies
A Green Roof at Sea
A Biophilic Oasis
A Green Roof for Every Angle
Community Focal Point
Nature in the City
Growing Lives
A Green Roof with Wings
A Policy Pioneer
A Dedicated Researcher
Designing a Better Future
Fire & Wind Standards
GHRC Professional Development Calendar
Welcome New Corporate Members
Green Wall Research
Standing the Test of Time

Green Roofs - Living Architecture Monitor - Summer 2009