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Green Roof System Using Recycled Carpet Fiber
The Nex Green Roof System was inspired by Japanese urban
garden design. Targeted at dense urban areas, this green roof system has many of the qualities of an
Extensive Green Roof System, but combines the aesthetics and recreation functionality of an Intensive System. Inner cities pose quality-of-life issues as well as environmental concerns;
a lack of green recreational space and views from offices and residences of desolate roofs reinforce the feeling
of a concrete jungle. Nex is a cost-effective system for the scale of city-center roofs and is
efficient for both new construction and retrofits. The Nex system uses post-consumer recycled
carpet, and addresses stormwater management concerns and the necessity for biodiversity in a dense
urban environment.
The system uses recycled olefin or nylon carpet fiber which
is diverted directly from the waste-stream and requires no additional processing. Natural soil is used which supports
biodiversity and avoids expanded shale which is energy intensive. The carpet matrix is self-supporting, eliminating
the need for a palette system saving material and transportation. The Nex system can be easily retrofitted for various types of flat roofs, without requiring
the replacement of roof membrane, and within the constraints of most roof membrane warranties. Removable sections
facilitate roof repairs; the perimeter of the roof which is most vulnerable to leaks is kept clear of soil and plant material, which
also avoids the necessity to raise flashing and railings. Removal of the stone ballast on IRMA roofs is not
required, it is incorporated into the system.
The Nex Green Roof System began with an
evaluation of the problems and issues of green roofs in dense urban areas where rooftops are a valuable real estate commodity
and where powerful incentives are needed to promote the adoption of green roofs. The environmental issues specific
to urban areas of stormwater discharge and filtration, the heat island effect, and the need for green
areas to promoe bio diversity, cooling and oxygen production. Most
green roof systems on the market rely on drought-resistant sedums that use CAM photosynthesis, where stomas close during
day to prevent water loss and open at night when less cooling is necessary. Light-weight expanded shale is used as the
growing medium, which combined with sedums have a desert feel, which is partly visual, but perceptually due to the
lack of evapotranspiration cooling that sedum plants do not provide. The Nex System provides a
more varied landscape using native plants and trees, natural soil which to filter the stormwater, is aesthetically pleasing,
comfortable, shaded, and provides usable recreation space.
The system uses recycled carpet fiber and
soil to form a moveable carpet that can be laid directly on an existing flat roof or over an existing Inverted Roof Membrane Assembly (IRMA) roof. The depth of soil undulates from 3” to 15” which
allows for the use of a wide range of native plants and allows for trees, creating shade and a more 3D visually appealing
effect. The increased soil depth encourages more biodiversity, allows for more possibilities in the selection of native
plants, and the thicker soild depth enables insects to survive through the winter.The carpet fiber mixed with
soil provides a support matrix and the double layer of water-retention felt creates a water reservois, allowing
for maximum water retainage of up to 3” of water and requires minimal additional irrigation. The use of native plants
and trees allows for the evapotranspiration of large amounts of water accommodating multiple rain events. |
