MODULAR GREENROOF TECHNOLOGY: AN OVERVIEW OF TWO SYSTEMS

1. MODULAR GREENROOF TECHNOLOGY:
AN OVERVIEW OF TWO SYSTEMS
By Linda S. Velazquez, ASLA Associate
Greenroofs.com
Publisher & Design Consultant
Presented at the First Annual Greening Rooftops for Sustainable Communities
Conference, Awards & Trade Show 2003, Chicago, IL
Modular Alternatives to Traditional Greenroofs
In order to better understand modular systems and the many advantages they offer, we
must address definition, application opportunities, and other reasons to consider
modular greenroofs. Depending on whether the greenroof is designed as either an
extensive or intensive one, we know greenroofs in general employ either a single-ply or
multi-ply waterproof roofing membrane, with a root barrier if the type of membrane is
organic in nature. A single or multi-layer drainage material follows, with a non-woven,
non-biodegradable filter fabric on top of the drainage layer to retain the soil media (Note:
Some drainage components include root barrier material in their filter fabric). Insulation
is optional although most often recommended, and may be located either 1) above (most
common) or below the roof deck; 2) above the roofing membrane (protected membrane,
common in Europe) or 3) below the roofing membrane (conventional), as determined by
the architect or contractor. Finally, the engineered substrate/soil media or planting
medium is determined and placed along with appropriate greenroof plants, according to
the landscape architect/greenroof designer.
So, many greenroof assembly designs are possible and available, ultimately determined
by the roof function. Of course, each greenroof location, building, and intended use is
unique, and should be designed specifically for the site and project at hand. But in any
case, the greenroofing system is applied on top of the entire roof deck surface, allowing
unimpeded drainage and a more even weight distribution over the whole roof. Modular
systems offer the same environmental, cost and energy saving benefits as a traditional
non-modular greenroof system, while also providing the soothing ecological beauty of
greenspace on otherwise forgotten and unused impervious rooftops ¹.
How is a Modular System Different?
With a modular system, the drainage, soil substrate or media, and the plants are self-
contained within a lightweight high-density polyethylene (HDPE) module, of varying
dimensions. In effect, these three main components of a greenroof are replaced by a
fully planted module. When interlocked, they offer continuous roof drainage and
coverage.

2. Why Consider Choosing a Modular System Over a Standard Multi-Layered
Greenroof?
Modular systems offer more overall flexibility for the designer and building owner in
terms of:
Simplicity of Design – the modules are engineered to contain the major elements of a
greenroof – drainage, soil media, and plants;
Easy Installation - modules can be brought up to the roof via service elevator or crane;
GreenGrid™ Module in elevator and during installation
Time-Saving Installation – the greenroof plantings can be grown off-site
simultaneously while the roof is being built or retrofitted until ready for deployment, and
due to the “instant” modular nature of the units, the overall actual roof installation time is
greatly reduced as the drainage layer, soil substrate and vegetative plantings are ready
to go and in most cases can be placed directly over the waterproofing membrane;

3. Off Site Planting - can be grown at any time of the year, and as such, can be placed on
a roof at any time of the year because the plants and root systems are already
established (Note: Most greenroofs are planted/seeded in the Spring or Fall);
Instant Roofscapes – fully pre-grown modules provide immediate aesthetic,
psychological, economic and ecological benefits for occupants and neighbors;
GreenGrid™ GreenTech®
Different Substrate/Soil Mix Types – each can be uniquely designed and filled for
specific plant needs to allow a greater diversity of vegetation;
Different Soil Depths – each module can vary according to the Master Plan and the
desired plant selection in a given module can reflect pertinent weight load restrictions,
e.g. deeper modules can accommodate woody plants and trees over load bearing
structures such as columns and beams;
Air and Water Flow – capacity to move air and water is increased, offering greater root-
zone airflow and drainage;
Irrigation – always optional, yet possible through traditional irrigation lines, drip irrigation
and/or rain capture with cisterns at roof or ground level;
GreenGrid™ Drip Irrigation
GreenTech® Irrigation Lines

4. Adjustment and Rearrangement after Installation – perhaps the greatest feature of
modular systems lies in the ability to allow for seasonal design changes and/or roof
membrane repairs or other roof maintenance issues. Physical flexibility is possible for
any reason with minimal disruption of other modular plantings or roof membranes.
What are the Unique Attributes of the Two Profiled Greenroof Modular Systems,
GreenGrid™ and GreenTech®?
Each company is certainly unique, offering both similar and different products and
services, to be evaluated as appropriate by the design professional. I will present an
unbiased look at both modular systems, with an overview of each of the two company’s
history and philosophy; product specifications; applications and case studies; and future
plans for the greenroof market (Note: All company and product information has been
taken directly from company promotional material and respective websites). For
complete information, please contact GreenGrid™ and GreenTech® representatives at
their Greening Rooftops for Sustainable Communities 2003 exhibitor trade show booths
or at their respective websites, listed below under References.
Profile #1: GreenGrid™ - “The Natural Choice for Your Roof”
Weston Solutions, Inc. (WESTON®), and ABC Supply Co., Inc. (ABC Supply) introduced
the GreenGrid™ System in August, 2001, and, according to their website, is considered
an innovative green roof technology that can boost a building's bottom line and value.
ABC Supply is the largest wholesale distributor of roofing and siding materials, tools, and
supplies in the United States. Founded in 1982, ABC Supply currently has over 200
locations in 41 states. Specializing in select product lines, they offer the professional
contractor (large or small) competitive pricing, superior pick-up and delivery service, and
the highest quality building materials available ³. WESTON® is a leading environment
and redevelopment firm, delivering comprehensive solutions to complex problems for
industry and government worldwide, with an emphasis on creating lasting economic
solutions for its clients 4. GreenGrid and ABC Supply Co., Inc. are trademarks of
American Builders & Contractors Supply Co., Inc., and GreenGrid System is a
proprietary technology of ABC Supply with U.S. and international patents pending.
WESTON is the sole licensee of the GreenGrid™ System in the U.S.
Simplicity of design and flexibility are the hallmarks of the GreenGrid™ roof system. The
system was designed by engineering, roofing and horticultural experts, and is the
product of years of research and testing. Testing of the system’s structural components
and lightweight recycled plastic materials has been underway since 1997. The result is a
complete green roof solution that is easy-to-install and maintain.

5. All the components of GreenGrid™ are engineered and provided through their system,
including the modules, soil media, plants, irrigation system, edge treatments, pavers,
water features and furniture. After the property owner and/or designer consults with the
GreenGrid® horticultural experts to select appropriate greenroof plants for the site, the
modules arrive fully planted and ready for installation. Modules are available in three
depths: 2”, 4” and 8” and standard sizes of 2’ x 2’ and 2’ x 4’. Various custom shapes
are also possible.
In a 2000 study conducted for the City of Chicago, WESTON estimated that greening the
rooftops of all city buildings in Chicago would result in nearly $100 million of annual
energy savings. Peak demand would be cut by 720 megawatts – the equivalent of
several coal-fired generating units or one small nuclear power plant. GreenGrid™
conducted temperature studies on their 4” and 8” Modules in August 2002, showing
highly reduced roof readings when greened – stormwater performance evaluations have
also been studied and analyses are available on the GreenGrid™ website ².
GreenGrid™ Modules:
Interior of Module Bottom of Module
GreenGrid™ Product Specifications:
ELEMENT DESCRIPTION
• Modules:
Standard – 2’ x 4’ and 2’ x 2’; Depth of modules (two depths) – 4” and 8”; Also 2’
x 2’ x 2” depth
Two inch depth modules weigh 10 lbs. wet
Four inch depth modules weigh 15 lbs. wet
Eight inch depth modules weigh 28 lbs. wet
• Pavers:
Length – 2 ft., width – 2 ft., depth – 1.5 in; Paver material - Recycled automobile
tires; Paver Colors - Forest green, black, brick
• Drainage/root barrier medium:
Geotextile
• Soil media:
Proprietary mixture consisting of organic and inorganic material
• Drip irrigation system:
Black polystyrene tubing
• Edge treatments:

6. Wood, composite recycled HDPE/wood (in various colors and designs), various
others to order
• Plants:
Perennials, grasses or shrubs specifically selected for climate, hardiness zone,
color and size.
Applications: Roof Gardens, Intensive and Extensive Greenroofs, Ground Level
Gardens
Case Study: GreenGrid™ Pilot Project, Beloit, WI, 2001 - Installation of the
GreenGrid™ at ABC Supply's corporate headquarters in August, 2001 gave ABC the
opportunity to turn undeveloped and unattractive roof space into useable and striking
gardens. The rooftop gardens are enjoyed daily by the employees of ABC Supply and
the ongoing research capability provided by the green roof will aid in offering all clients
proven rooftop plant selections, concrete energy savings data, and stormwater retention
data. The project was planned as a ‘showcase green roof’ and both intensive and
extensive GreenGrid™ modules were installed on the north and south roof portions of
ABC’s corporate headquarters. The north garden was designed as the “show” garden
and the south designed as both a show and research green roof. The research area is
used to experiment with the hardiness tolerances of potential rooftop plant species; to
quantify the GreenGrid™ insulating characteristics and stormwater management
features; and to test other potential system components.
GreenGrid™ applied at the ABC Headquarters in Wisconsin.

7. Profile #2: GreenTech® - “Roof Garden System”
GreenTech® has offices in the United States and the U.K. and introduced the ITM
modules to the sports market in 1995. The Roof Garden System had been since
researched and became available in 2002. Company philosophy seeks to produce roof
garden products that encourage the management of stormwater runoff, erosion control
and general environmental well being. According to their website, GreenTech® offers
several systems applications, consulting, design/build and construction services.
GreenTech® has the experience, expertise and systems to provide solutions to the world's
turf, horticultural and environmental needs, providing advice and solutions from some of the
premier experts in the world. GreenTech® systems are equally at home in college football
stadiums, championship golf courses and city rooftop gardens.
The modular design offers an infinite variety of configurations - from raised plots that
enable handicapped gardeners to gently undulating green spaces. What’s more, the ITM
system is the perfect answer for venues that need to go from sporting event to rock
concert overnight. A GreenTech® garden is tremendously flexible -- it can be placed on
a patio, raised off the ground for easy access or for gardeners with limited mobility, and
can support a wide variety of plants, even if they require different types of soils.
Healthy roof gardens and intensive greenroofs are possible without the load or drainage
issues. GreenTech’s Green Roof System helps you construct a light weight and efficient
green roof system on a wide variety of roofs and structures.
GreenTech® can work hand in hand with the property owner and greenroof designer to
recommend appropriate soil mixes and plants, but ultimately the client is free to select
and purchase both as desirable. GreenTech offers the flexibility of selecting either pre-
planting their modules off-site or assembling on-site at the discretion of the client. Built-
in drainage channels allow water to flow through the soil into the open channels and
directly to roof drain outlets. The contained environment and excellent drainage develop
and maintain healthier plants.
At the same time, high-density polyethylene module protects the roof surface from root
infiltration and damage to the roof membrane. Modules have a minimum 8” depth, but
can be planted to any depth. Fold up or custom height fences are attached and can
increase or vary soil substrate depths. Depending on the type of soil mix selected, a
non-woven filter fabric may or may not be required.
Modules measure 46” square, yet the trays can be cut on site to accommodate odd roof
contours. Modules interlock on plastic foot-locator pads that have knobs on each of the
corners, so four modules are joined by one foot-locator pad 5.

8. GreenTech® Module:

9. GreenTech® Product Specifications:
Applications: Roof Gardens, Intensive Greenroofs, Accents on Extensive Greenroofs,
Athletic Field Systems – Multi-use Venue and Permanent Fields, Erosion Control, Golf
Systems – Tee, Green and Portable Turf Nursery
GreenTech® Intensive Greenroof and Pond Bank Erosion Control Applications
Case Study: Residential Intensive Greenroof over condo garage in Chicago, IL,
2002 - Dan and Naomi Sachs were looking to create green and garden space on their
back patio for their young children. Living in downtown Chicago, green space is at a
premium in the city, so they decided to bring the park home. Because the Sachs wanted
an accessible and useable roof garden, the GreenTech System was a perfect fit. The
system was able to comply with strict weight requirements imposed by the condo

10. association, and the Sachs like the fact that their back yard could move with them if they
ever moved. Native and drought tolerant plantings, including flowering perennials, will
soon be added to enhance the bluegrass sod play area. From start to finish, this project
was completed in two days.
References
1. www.greenroofs.com
2. www.greengridroofs.com
3. www.abcsupply.com
4. www.westonsolutions.com
5. www.greentechitm.com