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The architectural firm of Hanbury Evans Wright Vlattas and Company (HEWV),
located in Norfolk, Va., resides in a four-story building with historical
significance in the rejuvenated downtown area. The building presented
a few logistical challenges and engineering concerns. The existing
wood-frame structure presented dead load limitations on its ability
to support a green roof. This could only be overcome by using a
lightweight system. Dan Bauserman, AIA, of HEWV selected the EnviroTech
Green Roof System from Virginia Beach, Va.-based Building Logics,
Inc.
The 4,500-square-foot roof project cost about $80,000 and was partially
funded with a grant from the Virginia Department of Conservation
and Recreation. Friends of the Norfolk Environment, a nonprofit
group, sponsored the grant, which was provided to assist the efforts
of cleaning the Elizabeth River and the Chesapeake Bay. The architectural
firm, which prides itself as a firm with a passion for the environment,
decided on the green roof to lead by example.
The green roof is being labeled as the first environmentally friendly
roof in Hampton Roads. It was designed to reduce and improve stormwater
runoff quantity and quality, reduce cooling costs, reduce heat island
effect, improve air quality and extend the life of the roof. Additional
marketing benefits have been realized by the firm relative to potential
clients visiting the roof. Several regional governments and organizations,
as well as the U.S. military and private corporations have toured
and attended seminars about the roof. The pride of ownership of
HEWV’s employees has also been an encouragement to the organization.
Green roofs are routinely credited with improving employee performance.
The project involved removal of the existing gravel-surfaced built-up
roof down to the wood deck. New insulation was installed to provide
greater energy efficiency. The mechanically attached insulation
was then covered with a gypsum-board thermal barrier. The German-designed
EnviroTech green roof membrane was then installed. The two-ply APAO-modified
bitumen roof membrane system was designed specifically for green
roof applications, and surpasses the requirements of the internationally
recognized FLL Guidelines. While providing the waterproofing for
the system, the membrane also incorporates an integral root barrier,
water retention system and drainage layer in one application. This
system simplifies the installation process and is the only system
that allows all of the components to be attached to the building
structure, including the plants. The roof membrane was then covered
with a geo-textile filter fabric, an engineered soil (growing media),
and sedum vegetation. While the EnviroTech system can be installed
on slopes up to 45 degrees, the structure provided a slope of about
10 degrees.
The diverse pallet of Sedum plants selected for the roof are all
native to the area, are frost- and drought-tolerant, and provide
a variety of colors and texture. Several of the plants will cover
the roof with a canopy of flowers in the spring and fall. Maintenance
on the roof is very minimal, and after the plants mature to full
coverage will provide an almost maintenance-free roof system. During
Earth Week in April, several of the employees had a roof-top maintenance
party to remove a few weeds that had sprung over the past year.
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