Chicago j douillard

Chicago City Hall
Case Study
9/20/11

Janaki Douillard

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Figure 1 Design Plan View of Chicago City Hall Green Roof

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Guide to Rooftop Gardening

PROJECT NAME: Chicago City Hall

CLIENT: City of Chicago

PROJECT LOCATION: Chicago, Illinois

COMPLETION DATE: Summer 2001

PROJECT SPECIFICATIONS2

GREEN ROOF CATEGORY: Combination of shallow and deep (semi-intensive)

NEW or RETROFIT: Retrofit

SIZE: 20300 sq.ft.

MEDIA DEPTH: 3.5-9 inches3

TYPE OF MEMBRANE: Thermoplastic polyolefin (TPO)4

COST: $2.5 million

DESIGNERS/MANUFACTURERS OF RECORD5

LANDSCAPE ARCHITECT: Conservation Design Forum

ROOFSCAPES CONTRACTOR: Church Landscape

ARCHITECT: McDonough + Partners

GREENROOF SYSTEM: Roofscapes, Inc. (later renamed Roofmeadow)

PROJECT ENGINEERING: Roy F. Weston, Inc.

GENERAL CONTRACTOR: Bennett and Brosseau Roofing

WATERPROOFING: Sarnafil

MAINTENANCE COMPANY: Chicago Department of Transportation6

2
Greenroofs.com
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http://www.roofmeadow.com/case‐studies/selected‐case‐studies/chicago‐city‐hall/
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5
Greenroofs.com
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GENERAL PROJECT DESCRIPTION

The Chicago City Hall’s green roof was designed as a test roof for the Urban

Heat Island project7 and as such had weather systems installed to monitor certain

atmospheric variables both on the green roof side of the building and on the black tar

roof which was on the County’s side of the building. This particular green roof sparked

the “greening” movement of Chicago, which led to Chicago’s new title of the “greenest

city in America.”

ECONOMIC BENEFITS

Energy Efficiency

Green roofs are known to lower the costs of heating and cooling a building

because they increase the insulation layer in the winter and reflect a lot of the heat that

would be retained on a black tar roof in the summer. The Chicago City Hall green roof is

no different, in fact it saves the City Hall $5000 a year on utility bills according to

Michael Berkshire.8 The National Research Council of Canada (2003) claims green

roofs can reduce the transfer of heat through the roof by 70-90% in the summer and 10-

30% in the winter, which lowers the overall energy usage by 75%.9

Increased Solar Panel Efficiency

Recently, it has become known that solar panels begin to decline in efficiency if

the ambient temperature on a roof increases too much on a hot day. The International

Green Roof Association encourages the use of green roofs and solar panels together

because green roofs naturally lower the ambient temperature on a roof, which results in

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8
Greenroofs.com
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Design Guidelines and Maintenance Manual for Green Roofs in the Semi‐Arid and Arid West –
pp:8

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higher efficiency of the solar panels.10 Solar panels are also easy to install on green

roofs, provide shade for low growing plants, and reduce wind levels that tear up

topsoil.11 The Chicago City Hall green roof does not incorporate the symbiosis of the

green roof-solar panel combination. The already exorbitant price of $2.5 million for the

Chicago City Hall green roof12 may have been a factor in their decision to opt out on the

solar panel inclusion. This green roof cost approximately $120/sq. ft, and with solar

panels costing approximately $100/ sq. ft13, the inclusion of solar panels would have

nearly doubled the price of this project.

Prolonged Membrane Durability and Longevity

Green roofs protect the roof membrane and can extend the useful life of a roof by

around 50% because it protects the membrane from weather and wear.14 The type of

membrane used on the Chicago City Hall green roof was a thermoplastic polyolefin

(TPO)15. TPO is a synthetic roofing material that serves the function of both

waterproofing membrane but also root barrier as a part of a green roof system. It is

important that the waterproofing membrane selected is resistant to chemical exposure

as are TPO membranes since chemical can leach through the green roof layer and

attack the membrane.16

10
http://www.igra‐world.com/engineering/solar_energy.php
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http://www.igra‐world.com/engineering/solar_energy.php
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http://www.greenroofs.com/projects/pview.php?id=21
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http://solarpowerauthority.com/how‐much‐does‐it‐cost‐to‐install‐solar‐on‐an‐average‐us‐
house/
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http://www.firestonebpco.com/roofing/tpo/

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Fire Prevention

Although green roofs can be a source of fire prevention in cities, on the Chicago

City Hall green roof that did not appear to be the priority. This green roof was designed

to be able to withstand the harsh wind and water conditions as well as the dramatic

seasonal shifts in Chicago, which meant utilizing a lot of the native prairie plants.17

Since prairie plants are designed to thrive with less water, they do not serve as well for

fire prevention as succulent plants.

Local Job Creation

Several of the firms hired to develop and maintain the Chicago City Hall green

roof were local Illinois companies. Conservation Design Forum, Church Landscape,

Bennett and Brosseau Roofing and the Chicago Department of Transportation were all

local companies employed in the creation of the City Hall green roof. It is surprising that

Chicago City Hall didn’t outsource more of their work to nonlocal green roof companies

since none of the local contractors had any experience with green roofs.18 Fortunately,

Chicago City Hall did employ a few local companies, which led to both Roofscapes Inc

and Church Landscape to go on and develop the green roof for the Chicago Center for

Green Technologies (CCGT) and the Peggy Notebaert Nature Museum.19 Conservation

Design Forum was employed again on the Peggy Notebaert Nature Museum as well.20

The Chicago City Hall green roof sparked the creation of many more green roofs

throughout Illinois. By 2008, there were 186,000 sq meters of green roofs in Chicago

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http://www.cityofchicago.org/city/en/depts/doe/supp_info/chicago_city_hallrooftopgardenp
lantsandmaintenance.html
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House transportation and infrastructure subcommittee on water resources
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alone, which was more than the combination of all other US cities.21 Job creation related

to green roofs rose 80% from 2004-200522 and green roof construction rose 30% in

2007 alone23. Not only did the Chicago City Hall green roof spark rapid proliferation of

green roofs but also it subsequently increased the projects available for these now

experienced local green roof companies to pick up.

Meeting Regulatory Requirements for Water Treatment of Urban Runoff

Green roofs are newly being considered and implemented for their aid in

reducing the burden stormwater events can take on the existing sewer systems and

waste water treatment plants. The Chicago City Hall green roof can retain 75% of a 1-

inch rainfall before the runoff begins to enter the stormwater system.24 In certain storm

water events, the runoff and sewer overflow can surpass the capacity of the water

treatment facilities in which case the excess is diverted into local waterways.25 Green

roofs can lessen the necessity of dumping raw wastewater into rivers and polluting local

eco-systems. Chicago’s new Water Agenda admitted that traditional stormwater

management techniques are insufficient in Chicago’s case and new “green

infrastructure” will need to be implemented in order to prevent over taxing the existing

sewer system.26 This new project and green infrastructure has the goal of reducing

storm water run off by 50%. 27


21
Chicago’s green revolution starts at the top
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pp. 9.
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Green roofs take root in cities across the country
24
http://www.cityofchicago.org/city/en/depts/doe/supp_info/chicago_s_city_hallrooftopgarde
n.html
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26
House Transportation and Infrastructure Subcommittee on Water Resources
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Reduce Community Resistance to new Developments

The aesthetic and “green” nature of rooftop gardens can limit the amount of

resistance local communities levy against new developments. Studies have shown that

creating more “green” spaces within urban environments can also dramatically increase

real estate prices.28 So not only do communities fuss less over new developments when

there are green roofs involved but real estate surrounding green roof areas is sought

after by local communities.

LEED and Opportunity for local, regional and national market exposure

Green roofs are a great technique to bring more awareness to a company or city.

Chicago has spent millions of dollars on greening up their city to earn the title the

“Emerald City” or the “Greenest City in America”.29 This new branding of Chicago has

increased tourism and real estate prices throughout the city. In nine years, Chicago

received nine awards and Mayor Daley himself received two from the American Society

for Landscape Architects (ASLA).30 Chicago has been recognized as a leader in green

roof development and in 2010 boasted 600 green roofs totaling an approximate 7 million

sq. feet.31 Green spaces in cities also denote areas of pride and investment that

contactors take into account when choosing new areas to develop.32

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American Society for Landscape Architects ASLA
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Roundup: Chicago benefits
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ENVIRONMENTAL BENEFITS

Creation and Preservation of Habitat and Increasing Biodiversity

The Chicago City Hall green roof created an entirely new ecosystem with more

than 150 varieties of plant life.33 There are 100 varieties of shrubs, 40 varieties of vines

and 2 varieties of trees that make up the total of 20,000 plants found on Chicago City

Hall’s rooftop (for a full list of plants used see index). Many of these plants are

perennials and were chosen for their low-maintenance tendencies.34 The City Hall green

roof also created a new habitat for bees with the incorporation of two beehives.35 These

two beehives not only produce over 150 lbs of honey every year but also increase the

biodiversity of the rooftop by providing a source of food for other insects that survive by

consuming bees.36

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Figure 2 Variation of Plant Life

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Temperature Regulation - Reduce ‘urban heat island effect’

The Chicago City Hall green roof was a pilot project called Chicago City’s Urban

Heat Island Initiative, which was designed to test the benefits of green roofs.38 Since

studying the temperature changes caused by the green roof was of such a central

interest to this project, consistent monitoring was set-up. Weather stations that recorded

temperature readings were positioned both on the green roof side of the building and

also on the black tar side that housed Cook County’s administrative offices.39 These

temperature readings were then recorded and studied by the U.S. EPA and Lawrence

Berkeley National Laboratory to determine the large-scale benefits of green roofs.40

After 10 years of monitoring the 2 difference roof sections, the average air temperature

on the green roof side has proven to be consistently 10-15 degrees F lower than the

black tar side.41 It was even shown that on hot days the temperature difference could be

as great as 50 degrees F.42

Improve Air Quality

It is well known that plants help cleanse the air of certain airborne pollutants and

some plants do this better than others. In the case of the Chicago City Hall green roof,

although the City does claim that the green roof improves air quality, there is little data

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n.html
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http://www.cityofchicago.org/city/en/depts/doe/supp_info/monitoring_the_cityhallrooftopg
ardensbenefit.html
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ardensbenefit.html
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United States: Greening the concrete jungle
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that supports how well this particular green roof garden is improving the air quality.43

The decision for certain plants over other plants was determined by the plants resilience

to harsh weather conditions like strong winds, little water and dramatically changing

seasons.44

Stormwater Management

Green roof systems absorb, slow and often filter the run-off produced by large

rainwater events. Deeper growth media systems as can be seen at the green roof on

Chicago’s City Hall, which reaches up to 9 inches of medium, are a huge aid in slowing

down run-off in event situations.45 The Chicago City Hall green roof utilizes a

combination of Type II and Type III systems (more info on Roofmeadow Type II and

Type III systems can be found in the Index), Type III being the 9 inches of medium is

designed for absorbing moisture and slowing the water discharge rate.46 Chicago’s

Climate Action Plan (CCAP) which includes utilizing green roof systems for their array of

benefits is also repaving streets and other hard surfaces with permeable, light colored

substitutes that help slow down stormwater and also reduce the Urban Heat Island

effect (UHI) by reflecting instead of retaining heat from the sun.47

Water filtration

As a natural part of a green roof system, the layers of the system provide a fairly

consistent method of water filtration. The water that does drain through the Chicago City

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n.html
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n.html
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http://www.roofmeadow.com/details‐specs‐services/details‐specs/type‐iii/
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United States: Greening the Concrete Jungle

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Hall green roof system has been filtered through several layers of medium and will have

removed much of the airborne pollutants the stormwater would have collected on its

way down through the atmosphere. This means that the water that does make its way

into the sewer system from the green roof will be less polluted and less taxing on the

city’s “aging” waster water treatment plant.48

COMMUNITY & SOCIAL BENEFITS

Aesthetics & New Amenity / Recreational Space

The greening on Chicago City Hall’s rooftop is naturally more aesthetically

appealing than the black tar on the County side of the building’s roof49. Unfortunately,

the design of this rooftop garden was not a recreational space, new amenity for the

citizens of Chicago or even open for public tours50. In order to appreciate the rooftop

garden on top of Chicago’s City Hall, one can view it from the neighboring Department

of Environment building or various other neighboring office buildings51.

Improved Health and Horticultural Therapy

Although the Chicago City Hall green roof was not designed with the added

health benefits that access to a natural environment can provide, it did create a sense of

pride and became the City’s symbol for its various “greening the city” initiatives. The

Chicago City Hall does recognize the effect higher city temperatures can have on health

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ardensbenefit.html
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and in that way promoted the use of more green roofs to lower the Urban Heat Island

effect and therefore lower diseases that arise from hot polluted climates.52

Noise Reduction, Blocking Electromagnetic Radiation

Green roofs have the benefit of being able to reduce noise levels within buildings

by 40-60 decibels.53 This does not appear to be the intention or even a foreseen

consequence of a green roof atop Chicago’s City Hall. Another unforeseen

consequence could be the green roof’s effect on honeybee livelihood. Green roofs

reduce the amount of electromagnetic radiation by up to 94%54 and research shows that

the recent decline in honeybees may be attributed to the increase in electromagnetic

radiation due to the proliferance of cell phones today.55 It is possible that reduction of

disturbing electromagnetic radiation atop the Chicago City Hall building may be

increasing the production of the two beehives on the roof than there might be otherwise

in such an urban environment.

Creating Ballast against Wind Uplift

The high winds that are seen atop skyscrapers can create wind uplift, which is

naturally a straining force on the roof. A heuristic for wind is that for every 10 stories up,

the wind speed doubles56, which means wind uplift just gets worse on taller buildings.

Green roofs provide enough weight on top of the roof that it can often counter the

pressure and strain that wind uplift causes on a roof, especially along the edges of a

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pp. 12
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pp. 12
55
Colony collapse disorder
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roof.57

Urban Agriculture

Although green roofs are capable of agricultural growth, the rooftop garden at

Chicago’s City Hall was not designed for food production. Rooftop gardens can provide

a source of local farming in cities, which reduces harmful emissions involved in

transportation and reduces overall cost. The Chicago City Hall rooftop garden may not

have incorporated urban agriculture because of the wind intensity 11 stories58 above

ground and the fact agricultural gardens need to be extensive systems. Since the

existing rooftop garden is semi-extensive, it is likely there was not enough extensive

flowerbed space to make an efficient vegetable garden. The high winds on the rooftop

also make the optimum plants not agricultural but native prairie plants59. Mayor Daley

did implement local growing at a different location in Chicago though. As a part of the

Chicago Organic plan, which aims to provide local food to Chicago citizens, a City Farm

was created and there are many local farmers markets within the city.60

Public Education

Green roofs can be a great opportunity for educating the public about rooftop

gardens or just gardens in general. Mayor Daley’s objective with this green roof was to

get the ball rolling in terms of environmental policies and as such he chose to begin with

a symbol of his dedication to environmentalism, the City Hall’s green roof. This symbol

may have done more for educating the populace about the possibilities of green roofs

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pp. 12
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n.html
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than any booklet or demonstration workshop could. After completing the Chicago City

Hall green roof, the City of Chicago went on to create more green roofs such as the

ones on the Chicago Center for Green Technology (CCGT), Millennium Park and the

O’Hare International Airport. This sparked the emergence of many green roofs in the

private sector within Chicago at some well-known companies such as Apple Store,

Walmart, Target, Best Buy and FedEx (For a more complete list of Private Sector and

Public Sector green roofs see the Index). In a more hands-on form of public education,

the city of Chicago did develop a demonstration program on the green roof at the Peggy

Notebaert Nature Museum.61 The City of Chicago Department of Environment also

developed a booklet of guidelines for creating a green roof in Chicago to make the

process easier and more user-friendly.62

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Figure 3 Cover of Green Roof Guidelines Brochure

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Greenroofs.com
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Reduction of Waste Volumes

The City of Chicago claims green roofs on average last 50% longer than

conventional roofs.64 There are other studies that claim they last even longer, 2.5-3

times longer.65 This all supports the fact that the less often roofs need to be replaced

the less waste is generated that ends up in landfills. Stable and lower roof temperatures

can also increase the effectiveness and useful life of HVAC systems and other rooftop

electronic systems, which are not only costly to replace but also to dispose of.66

SUMMARY

Chicago is in the unique position of having marketed itself as the “greenest city in

America.” Chicago also has more green roofs per square foot than all the cities in the

US combined. With the research done on its pilot project, the City Hall green roof,

Chicago now has the opportunity with all the data and clout it has collected to educate

and inspire other cities to follow in its footsteps. Chicago has been able to prove that

green roofs can lower urban temperature, help with stormwater management,

rejuvenate dilapidated communities, increase tourism and increase surrounding real

estate prices. Since green roofs are such a visual representation of greening the city,

they were a great first step in getting the citizens of Chicago on board for more green

technologies. Unfortunately, green roofs are expensive and have not made it to the

homes of the general population. Chicago now has the opportunity and challenge of


64
65
pp. 13.
66
pp. 13.

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finding a way to market green roofs to the everyday citizens of Chicago at a price they

can afford.

The constraints surrounding green roofs are that often they can be very

expensive to deploy, especially if the existing roof was not made to withstand the

additional weight of a roof garden. Extensive green roof systems generally weigh

around 20-34 lbs/sq. ft and Intensive green roof systems can weigh all the way up to

150 lbs/sq. ft.67 Even just an extensive green roof system could be doubling the weight

capacity of a Chicago roof if it was made to withstand only the required snow load of 30

lbs/sq. ft.68 If no structural additions were required in order to sustain a green roof, the

cost would still be around 50% more than the cost of a conventional roof.69 The

substantial cost of a green roof has made the movement into green roofs center mostly

in the public sector and commercial buildings. Most private home have not made this

green leap yet.

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68
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BIBLIOGRAPHY

A Guide to Rooftop Gardening. The City of Chicago Department of Environment, Mayor

Daley’s Landscape Task Force, and the Green Roof Infrastructure Committee.

American Society of Landscape Architects ASLA; Landscape Architects Gather in
Chicago for Annual Meeting on "Beyond Sustainability" Anonymous. Ecology,
Environment & Conservation Business. Atlanta:Oct 10, 2009. p. 22
Annual Green Roof Industry Survey. Steven Peck. Green Roofs for Healthy Cities. April

2011. www.greenroofs.org

Chicago's green revolution starts at the top; Rooftop gardens flourish in Windy City,
thanks to Mayor Daley Leslie Garrett. Toronto Star. Toronto, Ont.:Aug 14,
2008. p. T.2
Chicago City Hall. Greenroofs.com. 2010. http://www.greenroofs.com/projects/
pview.php?id=21
Chicago City Hall: Chicago, IL. Roofmeadow. 2011. http://www.roofmeadow.com/case-
studies/selected-case-studies/chicago-city-hall/
Colony collapse disorder. Laura Bellingan Biologist: Institute of Biology. 54 n. 3 Aug
2007. P. 124
Green Buildings, Roofs & Homes. City of Chicago: The City of Chicago’s Official Site.
2010-2011 City of Chicago. http://www.cityofchicago.org/city/en/depts/doe/
provdrs/green.html
Green fingers are spreading across the pond

Rosie Boycott. Evening Standard. London (UK):Sep 17, 2009. p. 15
Lisa Anderson. McClatchy - Tribune News Service. Washington:Sep 23, 2008.

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House Transportation and Infrastructure Subcommittee on Water Resources and

Environment Hearing - Impact of Green Infrastructure and Low Impact

Development on the Nation's Water Quality, Economy and Communities

Testimony by David Yocca. Congressional Documents and Publications. Federal

Information & News Dispatch, Inc. Sept. 30, 2010. p. 1-7

Roundup: Chicago benefits from seven million square feet of green roof space

Anonymous. Xinhua News Agency - CEIS. Woodside:Jul 30, 2010.

United States: Greening the concrete jungle; Cities and climate change

Anonymous. The Economist. London:Sep 3, 2011. Vol. 400, Iss. 8749, p. 29-32

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INDEX

Private Green Roofs:70

FedEx Cargo Relocation Project, Main Sort Building, Enterprise Rental Car Facility

Maintenance Building at O'Hare, FedEx Cargo Relocation Project, World Service Center

& Administration Building, Enterprise Rental Car Facility Customer Service Center at

O'Hare, FedEx Cargo Relocation Project, Vehicle Maintenance Building, Menards

Home Improvement Store, Shedd Aquarium, Aqua, Chicago Botanic Garden Daniel F.

and Ada L. Rice Plant Conservation Science Center, Fletcher Jones Mercedes Benz,

mkSolaire™ Smart Home at Museum of Science and Industry, 900 North Michigan

Avenue Parking Garage (Rush & Walton), Jewel-Osco Supermarket, Ronald McDonald

House of Chicago, McCormick Place Convention Center, Wal-Mart Store #5402, Bank

of America, Gary Comer Youth Center Green Roof, Chicago Residential Highrise 950 W.

Monroe, Home Depot Western Avenue, Target Store McKinnley, ABN AMRO, 2020

Green Dream, Target Store South Loop, Target Store West Addison, Schwab

Rehabilitation Hospital, Best Buy Elston Store, Apple Computer Store, Peggy Notebaert

Nature Museum, Sachs Residence

70
List from greenroofs.com

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Public Chicago Green Roofs: 71

O'Hare International Airport North Air Traffic Control Base Building, Chicago Midway

Airport Garage, O'Hare International Airport Mount Prospect Road Guard Post, O'Hare

International Airport Building 607 New South Vault and New Duct Bank Buildings,

O'Hare International North Air Traffic Control Tower ComEd Building, Chicago Cultural

Center, O'Hare International Aircraft Rescue and Fire Fighting (ARFF) Station #3,

Millennium Park, Soldier Field, Engine Company #98 Chicago Department of General

Services, Chicago Center for Green Technology (CCGT)

71
List from greenroofs.com

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Roofmeadow® Type II Data Sheet

Our experience demonstrates that the most efficient designs for the vast majority of American green roofs can be
derived from five basic green roof types (Type I, II, III, IV, V). Roofmeadow® has developed assemblies for each of
these types.

The selected assembly depends in part on project conditions including climate, desired plant community,
performance requirements, and load bearing capacity of the building. All assemblies will include the following
elements: 1) protection of the waterproofing membrane from root and biological attack, 2) protection of the
waterproofing membrane from physical abuse and accident, 3) a base drainage layer, 4) a separation layer to prevent
fine-grained engineered soils from fouling or clogging the drainage layer system, and 5) an engineered soil to support
the vegetation.

Type II: Single Media With Sheet Drain

Type II assemblies include a synthetic drain layer that offers a much lower resistance to water flow than growth
media. In this assembly, the drainage layer is a geocomposite sheet drain, and the growth media exhibits a moderate
permeability and porosity. A filter fabric separates the media from the underlying geocomposite sheet drain. The root-
permeable filter fabric keeps media fines out of the drainage zone. A common variation, used mostly in conjunction
with PMR roofing systems, utilizes a sheet drain with recesses to retain water. This type of sheet minimizes the loss
of moisture into the underlying insulation. To reduce plant stress during drought conditions, the drainage layer should
not exceed one-inch (2.5 cm) in thickness. Type II assemblies are probably the most common extensive assemblies
in the United States, and typical assembly thicknesses range from 3 to 6 inches (8 to 15 cm). This assembly is not
optimized for irrigation, which is not recommended in temperate climates.

The profile of a Type II assembly is as follows:

Wind Erosion Stabilization System
Growth Medium
Root-permeable Separation Fabric
Sheet Drain
Slope Stabilization Systems (for roof pitches exceeding 2:12)
Protection Layer
Root Barrier Membrane (when required)
Waterproofing System

Roofmeadow ♦ 7135 Germantown Ave., 2nd Floor ♦ Philadelphia, PA, 19119 ♦ o. 215.247.8784 ♦ f. 215.247.4659 ♦ info@roofmeadow.com

Roofmeadow® Type III Data Sheet
Our experience demonstrates that the most efficient designs for the vast majority of American green roofs can be
derived from five basic green roof types (Type I, II, III, IV, V). Roofmeadow® has developed assemblies for each of
these types.

The selected assembly depends in part on project conditions including climate, desired plant community,
performance requirements, and load bearing capacity of the building. All assemblies will include the following
elements: 1) protection of the waterproofing membrane from root and biological attack, 2) protection of the
waterproofing membrane from physical abuse and accident, 3) a base drainage layer, 4) a separation layer to prevent
fine-grained engineered soils from fouling or clogging the drainage layer system, and 5) an engineered soil to support
the vegetation.

Type III: Dual Media

The dual media Type III assembly utilizes a granular mineral drainage media layer beneath a lightweight, fine-grained
growth media. A root-permeable separation fabric separates the media layers and keeps the growth media fines from
mixing with the granular media. The permeable granular media base provides several advantages; it 1) absorbs
moisture, 2) provides additional hospitable volume for root growth, and 3) moderates the rate at which water is
discharged from the green roof. This assembly best approximates the natural conditions associated with shallow soil
over shale bedrock. Assembly thicknesses typically range from 4 to 8 inches (10 to 20 cm). Compared to Type II
assemblies of a comparable thickness, Type III assemblies are significantly more drought tolerant and accommodate
a broader plant palette, even supporting turf in many climates. Type III green roofs promote strong plant growth by
draining and distributing water efficiently and concentrating root mass in a stable temperature and moisture zone. If
irrigation is required, then highly efficient base capillary irrigation introduces water at the root level, an approach that
minimizes water loss from evaporation and promotes deep root development.

The profile of a Type III assembly is as follows:

Wind Erosion Stabilization System
Growth Medium
Root-permeable Separation Fabric
Light-weight Granular Drainage Media
Protection Fabric (for un-irrigated systems)
Capillary Fabric (for irrigated systems)
Root Barrier Membrane (when required)
Waterproofing System

Roofmeadow ♦ 7135 Germantown Ave., 2nd Floor ♦ Philadelphia, PA, 19119 ♦ o. 215.247.8784 ♦ f. 215.247.4659 ♦ info@roofmeadow.com

Growing medium. Providers recommended custom mix of organic and inorganic materials that will
support vigorous growth of the specified plant species, complying with the following requirements of the
German FLL standards:

Extensive Soil Intensive Soil Drain Material

one layer multi layered soil mixture bulk material
mixture
PHYSICAL PROPERTIES

Water retention min. 25 % min. 35% min. 50% min.15%
(without water
(compressed condition)
damming)
Water permeability min. 60 mm/min min. 0,6 min. 0.3 mm/min min. 180
mm/min
(compressed condition) mm/min
Air content min. 25% min. 15% min. 20%
(fully saturated)
3 3 3 3 3
Weight (density) 0.8-1.4 g/cm 1.0-2.2 g/cm 1.4-2.2 g/cm 1.0-1.8 g/cm 0.8-1.8 g/cm
dependent on
(fully saturated)
the material

CHEMICAL PROPERTIES

pH-value 6.5 - 9.5 6.5 - 8.0 6.5 - 7.5 6.5 - 8.0
Salt content of water max. 1 g/liter
extract
(recommended, if
possible)
Initial organic matter 3-8 % 3-6 % 6-12 %
Nitrogen (N) slightly max. 60 mg/liter max. 60 mg/liter
soluble
Phosphorous (P2O 5) max. 150 mg/liter max. 200 mg/liter
Potassium (K2O) min. 150 mg/liter min. 150 mg/liter
Magnesium (Mg) max. 120 mg/liter max. 120 mg/liter

QTY. BOTANICAL NAME COMMON NAME

45 Achilea millefolium 'Paprika' Yarrow
20 Achillea millefolium 'Heidi' Yarrow
35 Achillea sp. 'Schwelienburg'
40 Allium canadense wild onion
30 Amorpha canescens leadplant
125 Andropogon scoparius little bluestem grass
20 Anemone canadensis meadow anemone
60 Anemone patens wolfgangiana pasque flower
10 Anemone virginiana tall anemone
35 Aquilegia canadensis American columbine
24 Arabis caucasica 'Flore Pleno' Fiore Pleno arabis
24 Artemisia shmidtiana 'Silver Mound'
30 Artemisia sp. 'Powis Castle'
24 Artemisia stelleriana 'Silver Brocade'
30 Asclepias tuberosa butterfly weed
37 Asclepias verticillata whorled milkweed
50 Aster azureus sky blue aster
25 Aster ericoides heath aster
25 Aster laevis smooth blue aster
35 Aster novae-angliae New England aster
30 Aster obiongifolius aromatic aster
30 Aster ptarmicoides upland white aster
20 Aster sericeus silky aster
20 Astragalus canadensis milkvetch
40 Baptisia leucophaea cream wild indigo
10 Blephilia ciliata Ohio horse mint
60 Bouteloua curtipendula side-oats grama
580 Bouteloua gracilis blue gramma
485 Boutelous hirsuta hairy gramma
725 Buchloe dactyloides buffalo grass
35 Callirhoe involucrata wine cups
60 Campanula poscharskyana Serbian belfflower
25 Campanula rotundifolia harebell
445 Carex Bicknellii Bicknells sedge
105 Carex cephalophora woodbank sedge
100 Carex gravida sedge
100 Carex grayi 'Morning Stae sedge
1060 Carex pennsylvanica Pennsylvania sedge
32 Cassia fasciculata partridge pea
10 Ceanothus americanus New Jersey tea
12 Ceraatium tomentosum 'Silberteppich'
15 Chrysanthemum Leucanthemum ox-eye daisy
40 Coreopsis auriculata'Nana' Coreopsis

15 Coreopsis lanceolata sand coreopsis
190 Corydalis flexuasa 'Blue Panda' blue corydalis
230 Corydalis lutea yellow corydalis

440 Danthonia spicata poverty oat grass
15 Desmanthus illinoensis Illinois sensitive plant
32 Dianthus allwoodii 'Helen'
32 Dianthus alpinus allwood pink
400 Dianthus carthusianorum dianthus
370 Dianthus deltoides dianthus
70 Dianthus gratianopolitanus 'Tiny Rubies'
35 Dianthus gratianopolitanus ‘spotty’
20..Dianthus gratianopolitanus v. gra cheddar pinks
240.Dianthus plumarius dianthus
15 Dodecatheon meadii shooting star
85 Echinacea purpurea purple coneflower
20 Echinops bannaticus 'Blue Glow'
85 Elymus canadensis Canada wild rye
85 Elymus villosus silky wild rye
IO Eryngium yuccifolium rattlesnake master
35 Euphorbia polychroma cussion spurge
400 Festuca amethystina 'Bronzegianz'
400 Festuca glauca 'Elijah Blue'
32 Gaillardia 'Kobold' Blanket Flower
55 Geranium sanguineum Cranesbill
20 Geranium sanguineum 'Max Frei’ Cranesbill
30 Geranium sanguineum var. striat Cranesbill
40 Geum cor-cineum 'Borisii' Geum
60 Geum trfflorum prairie smoke
12 Gypsophila repens 'Rosea'
12 Gypsophila repens creeping baby's breath
25 Helianthus mollis downy sunflower
20 Helianthus rigidus showy sunflower
110 Helictotrichon sempervirons blue oat grass
45 Hemerocalis 'Anzac' Daylily
45 Hemerocallis 'Liftle Wine Cup' Daylily
20 Hemerocallis'Stelia d'Oro' Stella d'Oro daylify
20 Heuchera brizoides'Huntsman' Coralbelis
45 Heuchera brizoides 'Red Spangif’ Coralbells
10 Heuchere richardsonii prairie alum root
435 Hieracium piloselia hieracium
100 Hystrix patula botdebrush grass
157 lberis sempervirens candytuft
497 Juncus tenuis path rush
45 Knautia macedonia knautia
457 Koeleria cristata June grass
445 Koeleda glauca large blue hair grass
20..Lavandula angustifolia 'Munsteac’ Munstead lavender
60 Lavandula angustifolia 'Hidecote' Hidecote lavender
10 Lespedeza capitata round-headed bush clover

75 Leymus arenarius blue lyme grass
30 Liatris aspera rough blazing star
47 Liatris cylindracea dwarf blazing star
32 Linaria vulgaris bufter-and-eggs
25 Lobelia inflata Indian tobacco
25 Lychnis'Flottbeck' Campion
20 Monarda 'Cambridge Scarlet' Bergamot
10 Monarda fistulosa wild bergamot
47 Opuntia humifusa prickly pear cactus
20 Origanum vulgare odganum
110 Panicum leibergii prairie panic grass

110 Panicum leibergii prairie panic grass
85 Panicum virgatum switch grass
45 Papaver orientate poppy
20 Papaver orientale 'Brilliant' poppy
10 Parthenium integrifolium wild quinine
10 Penstemon digitalis foxglove beard tongue
10 Penstemon pailidus pale beard tongue
65 Penstemon 'Prairie Dusk' Obedient plant
70 Penstemon sp. 'Utahensis'
182 Petalostemum candidum white prairie clover
255 Petalostemum purpureum purple prairie clover
295 Petrorhagia saxigrage petrorhagia
112 Phlox bifida sand phlox
165 Phlox sp. 'Emerald Cushion Blue'
12 Phlox sp. 'Emerald Pink'
15 Polemonium reptans Jacobsladder
15 Potentilia argute prairie cinquefoil
10 Prenanthes alba lion's foot
25 Ranunculus rhomboides prairie buttercup
20 Ratibida columnifera mexican hat
15 Ratibida pinnata yellow coneflower
10 Rosa carolina pasture rose
45 Rudbeckia subtomentosa sweet black eyed Susan
215 Ruellia humilis hairy ruellia
75 Salvia nemorosa 'Mainacht' Purple Saivia
25 Scutelaria parvula small skullcap
320 Sedum acre wall pepper
655 Sedum album white sedum
540 Sedum floriferum sedum
620 Sedum hybridum sedum
95 Sedum kamtschatcum orange stonecrop
380 Sedum 'Mochren' Mochren sedum
450 Sedum reflexum sedum
720 Sedum sexangulare sedum
185 Sedum spectible 'Matrona' Matrona sedum
520 Sedum spurium sedum
185 Sedum 'Vera Jameson' Vera Jameson sedum
190 Sempervivum arachnoideum hens and chicks
450 Sempervivum-Hybriden sepervivum
15 Smilacina racemosa False Solomons seal
15 Solidago flexicaulis broad-leaved goldenrod
20 Solidago juncea early goldenrod
25 Solidago nemoraiis old-field goldenrod
20 Solidago speciosa showy goldenrod
15 Solidago ulmifolia elm-leaved goldenrod
110 Sporobolus heterolepis prairie dropseed

25 Stachys byzantina 'Helene von Stein'
125 Thymus praecox 'Coccineus' 'Coceineus'
112 Thymus praecox 'Albiflorus' 'Albifforus'
625 Thymus serpylium thymus
10 Tradescantia ohiensis common spiderwort
30 Tradescantia ohiensis 'Zwanenbi’ spiderwort
432 Trifolium arvense rabbitfoot clover
50 Viola sororia common blue violet

Trees
1 Crataegus crusgalli Cockspur hawthorn
1 Malus ioensis prairie crabapple

Shrubs
5 Diervilla lonicera dwarf bushhoneysuckle
24 Juniperous chinensis 'Sea Greer’ sea green juniper
11 Kerria japonica Japanese kerria
24 Microbiota decussata Russian arborvitae
26 Miscanthus sinensis var.gracillin Maiden grass
11 Rhus aromatica'Gro-low' gro-low sumac
11 Symphoricarpus alba snowberry

Vines
11 Celastrus scandens American bittersweet
22 Parthenocissus tricuspidata Boston ivy
4 Clematis virginiana virgins bower

LANDSCAPE MAINTENANCE PLAN
The following maintenance operations are suggested to best care for the plants that will be part of the City
Hall green roof system.

Installation Care - Gardener
1. Post Planting Care - A component critical to the establishment of the plants is supplemental watering
during the first growing season. This will include immediate watering after planting, and then up to 36
occurrences or 3 times per week for 13 weeks. This is especially important during a hot dry spell.

2. Weeding - As the plants begin to establish, weeds or undesirable volunteer plants may become
prevalent until the new plants provide some competition. It will be important to work with a gardener who
knows how to identify these undesirable plants and remove them in a timely manner, i.e., before they have
had time to set seed. This will need to be done at least 3 times a week immediately after planting for 8
weeks and then tapered to 1 time per week for the remaining weeks of the growing season.

3. Dead Heading Perennial and Herbaceous Plants -To ensure that the plants look their best all season,
it is important to remove spent flower blossoms every week. This will maintain the plants’ health, shape,
and aesthetic qualities.

4. Staking - Containerized garden plants, especially perennials, can get lanky, therefore, it is important to
have a staking program where weekly the plants are checked to see if they are leaning or losing their form.
Use green bamboo (or similar aesthetically pleasing staking tool) to tie up and keep the perennials in
organized masses.

5. Erosion Control - The garden should be checked for any areas that are susceptible to wind or water
erosion. Any areas that show signs of erosion should be repaired and steps taken to prevent future erosion.

Long-term Care - Landowner Care (also includes items listed above)
1. Monitoring Program - A regular, bi-weekly monitoring program assessing the condition of the garden
and plants will be important for containing any pest problems before they spread, as well as making sure
that the plants are growing well in the areas they were planted. Monitoring will also bring about new ideas
for supplemental planting, redesign, or species replacement.

2. Supplemental Planting - There may be areas where the selected plants do not grow or thrive as
anticipated. To ensure that the rooftop always looks its best, it is important to budget for an annual
supplemental planting program. Also, as the crowns of the trees and shrubs develop, additional shade-
tolerant species should be planted.

3. Perennial Division Program - Over time perennials need division in order to grow well. The divided
perennials can then be placed in other spots of the garden, or be utilized for other purposes, like planting
them in other green roofs, employee give-aways, etc. This program should be performed every 3 to 4
years.

4. Pruning/Trimming - The woody plants will need a regular program of trimming excess growth,
maintaining the shape of the woody trees, and keeping open canopies to promote healthy growth and
aesthetic value. This program should be performed mainly in the late season.

5. Tree Root Pruning - Since the trees will be in a confined space, a tree root pruning program, performed
every 3- to 4-years, will be needed to keep the trees contained in their small rooting areas. A specialized
arborist service should be contracted to evaluate the proper way to prune the roots to maintain health and
contain the plant. This process is similar to bonsai root pruning.

6. Pest Control - Although a good maintenance program minimizes pests and diseases, there may be
unpredicted stressors that could affect the plants’ health. There could be situations where aphids or mites
afflict the plants, or the pest may be mice or pigeons that become a nuisance and impact the health of the
plants. A budget amount for pest control will be needed.

7. Mechanical Equipment - The green roof is located near the building’s mechanical equipment. Areas
surrounding this equipment should be checked regularly and should be kept clear of vegetation.

8. Drainage - The overflow boxes and drains should be checked monthly and should be kept clear of any
obstructions.

9. Irrigation System Maintenance/Winterizing - Part of the maintenance program will include maintaining
the irrigation system. Drip irrigation systems may need to have some lengths replaced. Additionally, the
system’s water has to be emptied as part of winterizing. In some instances, an early freeze may cause the
residual water to freeze and the pipes to crack, resulting in the need to replace the PVC pipe.

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