Green Roof Constructability

Michael Murphy
September 1, 2008 — 1,249 views  

An analysis of green roof constructability concerns was conducted by Ryan Kline, an experienced LEED (Leadership in Energy and Environmental Design)-accredited professional and superintendent for Turner Construction Company. Mr. Kline reported that green roofing technologies, whether intensive or extensive, continue to evolve as design professionals and builders retool their skills in response to emerging technology in improvements to insulation, water retention and drainage, and habitability.

Through continuing education and active participation, project teams can minimize constructability concerns involving this dynamic roofing system, and many industry experts encourage the interactive synergy gleaned from the collaboration-in-design approach to construction.

What is the single most important element in any design? According to Mr. Kline, it is “collaboration.” It is critical that all members of a project team (project owners, designers, engineers and builders) collaborate to share their insight in designing building systems. As some building systems have more inherent complexities than others, and given the unique challenges of green roof design, the project team should consider the following issues during the design process:

1. Access—Consider that construction crews and facilities maintenance staff may require different paths of roof access.

2. Specifications—Require two leak/flood tests; the first of which follows installation of the waterproofing layer, the second follows completion of the green roof.

3. Type—Choose intensive or extensive green roof design. The selection of green roof type will be influenced by construction schedule constraints, market availability, seasonal restraints (long lead time for growth of vegetation), trade proficiency and compatibility of adjacent materials (waterproofing, insulation and growth medium).

4. Irrigation—Coordinate irrigation and drainage systems. Irrigation may be designed to service roof and street-level landscaping.

5. Compliance—Incorporate local zoning requirements and regulations.

6. Incentives—Obtain LEED certification (design to achieve maximum credits), positive publicity and municipal tax incentives and/or funding.

Michael Murphy

Michael K. Murphy, LEED AP, was an elected member of the board of directors for the Detroit Regional Chapter of USGBC. Mr. Murphy's background includes over $300 million in construction of industrial, commercial, educational and health care projects. As a member of Turner's Michigan Green Team, Mr. Murphy supported the construction of Turner's green projects, including: the Blue Cross/Blue Shield Parking Deck (Certified); Haworth, Inc. Corporate Headquarters (Gold); Harper Woods Library (Silver); Metropolitan Hospital (Gold); and Henry Ford West Bloomfield Hospital (Silver). His current assignment is manager of engineering for Turner Construction Company in Salem, Oregon. He is working on a "green" Patient Care Tower at the Salem Hospital campus, which is seeking certification under the Green Guide for Health Care (GGHC) rating program.