Green roofs have been a part of building for over a thousand years. The current green building movement has, however, had the greatest impact on the growth of the green roofing industry.
A green roof is commonly defined as a roof that consists of vegetation and soil, or a growing medium, planted over a waterproofing membrane. There are two basic types of green roofs, an extensive roof, which has a few inches of soil cover and an intensive roof that has two feet or more of soil for a variety of grass, trees, bushes and shrubs.
Green roofs are used in a multitude of buildings, including industrial facilities, commercial offices, retail properties and residences. The benefits of a green roof include reduced storm-water runoff, absorption of air pollution, reduced heat island effect, protection of underlying roof material from sunlight, reduced noise, and insulation from extreme temperatures. A green roof can thus be a critical design element for a green building.
As more properties across the country are attempting to obtain LEED certification, it is worth noting that a green roof can help a property obtain over a dozen LEED credits, including credits for reduced site disturbance, landscape design that reduces urban heat islands, storm water management, water efficient landscaping, innovative wastewater technologies and innovation in design. The increase in green roofs and the green building movement is also resulting in an increase in liability resulting from errors in the design, installation or maintenance of green roofs. As a result, owners, design professionals and contractors should carefully consider ways to mitigate the potential risks involved with building a green roof.
Set Expectations Right
In order to mitigate liability, the stakeholders in a project that features a green roof should clearly detail their expectations and performance requirements in their contracts. This will require preparing contracts that might not easily fit within standard forms of architect and construction contracts. A clear example of green roof liability was detailed at the AIA Convention 2007 . In that instance, the green roof contractor and structural engineer failed to communicate the specifics of the green roof. The result was water leakage and sizable damage. This scenario could have been avoided by simple communication.
One can easily imagine potential disputes arising from any of these following situations,
- failure to deliver the energy efficiency levels claimed by the installation of a green roof,
- failure to deliver a green roof that results in the claimed number of LEED credits that should be awarded by the USGBC ,
- mold or other environmental hazards as a result of poor maintenance of a green roof, or
- a roof collapse resulting from a green roof that was not properly constructed, installed or maintained.
Parties should look to limit unnecessary liability by drafting contracts that clearly detail how the applicable parties will be responsible for each of the above-mentioned items. Although liability for said items is not able to be eliminated, it is important to all stakeholders that it is appropriately detailed in contract form, instead of by a judge or jury.
Hire an Expert
Green building owners and general contractors should engage experienced green roofing professionals when building a green roof. The green roofing industry has begun to assist in this regard by designating such professionals in a manner similar to that of the USGBC’s Green Associate or Accredited Professional designations. Green Roofs for Healthy Cities has established the Green Roof Professional (“GRP”), which designation was created to distinguish certain individuals that have achieved a specific knowledge level with regard to green roof design, project management, installation and maintenance. The goal of the designation level is to allow green roofing professionals to differentiate themselves, establish an increased level of professionalism in the green roofing industry and help protect the public health, safety and welfare by the building of better green roofs. I would strongly encourage clients to seek GRPs when working on a green roof in an attempt to mitigate unforeseen liability. It is worth noting, however, that one likely unintended consequence of this accreditation program for GRPs is that they could very well be held too a higher standard of care should any problems occur following the installation, repair or maintenance of a green roof.
Green roofs provide a benefit to the environment, energy efficiency related savings to property owners and tenants and potential credits for owners seeking LEED or other third party green building certification for their property. The legal risks and potential liabilities of green roofs should, however, be carefully examined, both by companies considering installing a green roof and by green roof professionals themselves before getting involved with any green roofing project.
This post is made with the permission of Consilience, the blog of the Institute of Green Professionals.
[photo credit: Dionetian]
This is an excellent article. Green roofs make so much sense – for energy efficiency, conserving our resources and giving us another source of potential food supply. Imagine combining green roofs with square foot gardening!
Thanks for a timely and informative piece.
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