'Green roof' is county's first

Northern Montgomery County's first non-residential green roof has been successfully installed in a three-story office building by Therrien Waddell Construction Group (TW). The 8" to 12" sedum plants will blanket the roof of Germantown's 19875 Crystal Rock Drive, and once mature, will act as a natural stormwater management system, will reduce the building's heating and cooling costs, and will improve the environment in the surrounding community. According to TW President Jerry Therrien...

GERMANTOWN, MD, Nov. 7 -- Northern Montgomery County's first non-residential green roof has been successfully installed in a three-story office building by Therrien Waddell Construction Group (TW). The 8" to 12" sedum plants will blanket the roof of Germantown's 19875 Crystal Rock Drive, and once mature, will act as a natural stormwater management system, will reduce the building's heating and cooling costs, and will improve the environment in the surrounding community.

According to TW President Jerry Therrien, "Green roof construction in the United States is relatively new. In order to engineer this phase of the building, TW contacted and arranged to meet with manufacturers' reps and subcontractors experienced in constructing this type of system. It was an education from the ground up."

The cost to build a green roof is high -- in this case $350,000 for the $7.5 million building. The roof system has many more layers than a standard roofing system, and the waterproofing components are much thicker and more durable than most conventional roofs. On top of the membrane lies a blended mix of mineral, organic, synthetic and fertile topsoil to sustain and nurture the plants.

"Couple this with the added weight of the steel and a concrete roof deck, and you have a much more expensive system," Therrien explains.

Offsetting the high price tag of the green roof construction is the fact that there is a diminished need for -- and therefore reduced cost associated with -- on-site or off-site stormwater facilities; the green roof acts as a natural stormwater management system. Montgomery County also reduced the fees that The Williamson Group, the building's developer, paid by approximately $75,000 for constructing an eco-friendly roof. The life span of a green roof, time-tested in much of Europe, is 50 to 60 years, considerably longer than the 20 to 30 years for a conventional roof.

Less quantifiable, yet equally important, is the benefit this roof signifies for the environment. The amount of carbon dioxide converted to oxygen from one green roof can improve the air quality. Roof plants can process airborne toxins through photosynthesis, reduce noise pollution, and reduce heat island effects (a phenomenon where city or metropolitan temperatures are warmer than rural areas, thereby impacting energy demand, air conditioning costs, pollution, and health issues).

"The more eco-friendly roofs we build, the more efficient we will become at installing and handling these materials, which will lead to reduced costs. Better and less expensive materials to build these roofs may also be developed as further experience and technologies improve. Plus, greater government incentives would definitely encourage more of this kind of construction in the future," projects Therrien.

Montgomery County's new "Green Building Law" which was passed Nov. 28, 2006 and will become mandatory by Sept. 1, 2008, will require nonresidential buildings over 10,000 square feet to achieve a LEED (Leadership in Energy and Environment Design) silver rating, a national benchmark for the design, construction and operation of high-performance green buildings.

Since his work on the green roof project in Germantown, Therrien and members of his team are convinced that that "Green" is the wave of future and will commit to becoming a LEED-certified contractor.

"Increasingly, construction is going 'green.' To stay competitive, we have to know how to build green buildings, how to offer our clients options to stay within the 'Green Building Law'," Therrien says.

Therrien Waddell Construction Group completes interior construction projects for office, laboratory, industrial and retail build-outs, and ground-up construction projects on shopping centers, corporate offices, community centers, dormitories, religious structures, car dealerships, warehouses and institutional headquarters in Maryland, Virginia and Washington, DC.

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