Fall/Winter 2005
INTRO PAGE
Contents
1. An Introduction
2. Green Roofs:
3. Electronic Roof
Moisture Survey and
Solar Roof
Membranes
4. Project Spotlight
CRA/CRS
Commercial Roofing Solutions, Inc.
1187 Main Avenue, Suite 3A
Clifton, NJ 07011
TEL: (212) 564-0532
(973) 772-0100
FAX: (973) 772-0055
EMAIL: office@roofingsolution.com
1
Green Roofs…More Than Just Grass
What Is a Green Roof?
A green roof, also known as a vegetated roof cover or eco-roof, is a thin layer of living vegetation
installed on top of conventional flat or sloping roofs. Green roof systems may be modular, with drainage
layers, filter cloth, growing media and plants already prepared in movable, interlocking grids; or each
component of the green roof system may be installed separately. Green roof
development involves the creation of "contained" green space on top of a
man-made structure.
Green roofs are divided into two categories, which vary in vegetation,
depth, and also slightly in structure. Extensive green roofs have a depth range
between 3 and 6 inches, and are frequently designed to satisfy specific
engineering and performance goals. They are ideal for locations that receive
little maintenance and generally support vegetation
that can withstand harsh growing conditions. The
entire system of an extensive green roof is lightweight
and can be safely installed on almost any existing roof. Intensive green
roofs, which may become quite deep (7 inches or deeper) and merge into
more familiar on-structure plaza landscapes, incorporate plants that
require regular maintenance, such as watering, fertilizing and mowing. A
myriad of vegetation is able to grow upon an intensive green roof’s thick
layers, including sod grass lawns, perennial and annual flowers, shrubs,
and even small trees.
The challenge in designing extensive green roofs is to replicate naturally
green open space and its benefits, while keeping these roofs light and affordable.
Thus, the new generation of green roofs relies on the combination of horticulture
science, waterproofing, and engineering.
The Structure of a Green Roof
The waterproofing component of a green roof is
by far the most important factor for the long-term
success for the system. A typical green roof is a composite
system of several layers of protective materials to achieve
waterproofing and to convey water away from the roof deck.
All well-designed green roofs include subsystems
responsible for:


Drainage: Green roof drainage design must both maintain optimum gro
wing conditions in the growth medium and manage heavy rainfall without
sustaining damage due to erosion or ponding of water
Figure 2. Generic Extensive Green Roof
Courtesy of Optigrün Intl. AG

2


Plant nourishment and support: The engineered medium must meet exacting requirements for grain-size
distribution, void ratio, moisture retention, etc. and
Protection of underlying waterproofing systems: Green roof assemblies must protect the underlying
waterproofing system from human activities (including the impact of maintenance) and biological attack.
A wide range of methods can achieve these functions. For instance, drainage layers may consist of plastic sheets,
fabric or synthetic mats, or granular mineral layers. Similarly, the physical properties and performance
characteristics of growing media (engineered soils) and plant materials may vary with the climate, plant
community, or engineering requirements. Figure 2 shows a generic cut-away of a common type of green roof
assembly that utilizes a lower granular drainage layer in combination with an upper growth medium or substrate.
The Green Roof Advantage
Both private and public benefits emerge from a green roof system.
Green roofs protect conventional roof waterproofing systems while adding a wide range of
ecological and aesthetic benefits. They are a powerful tool in combating the adverse impacts of land
development and the loss of open space.
3