esign guidelines d for green roofs

by Steven Peck and Monica Kuhn, B.E.S., B. Arch, O.A.A.

ABSTRACT

Green roof infrastructure promises to become an increasingly important option for building owners and community planners. As we move into the 21st century, green roofs can address many of the challenges facing urban residents. Life cycle costing indicates that green roofs cost the same or less than conventional roofing and they are an investment which provides a significant number of social, environmental and economic benefits that are both public and private in nature. These benefits include increased energy efficiency (from cooling in the summer and added insulation in the winter), longer roof membrane life span, sound insulation, and the ability to turn wasted roof space into various Fig. 1– Pelgromhof Senior’s Residence Green Roof types of amenity space for building Amersfort, Netherlands Photograph courtesy of S. Marshall occupants. Green roofs filter particulate matter from the air, retain and cleanse storm water and provide new opportunities for biodiversity preservation and habitat creation. They generate aesthetic benefits and help to reduce the ‘urban heat island effect’ - the overheating of cities in the summer which contributes to air pollution and increased energy consumption.. This article provides an introduction to green roof infrastructure and describes how to implement and market a green roof, looks at costs, and presents three case studies.

Ontario Association of Architects LEARNING OBJECTIVES

After reading this article you should understand:

1. The elements of a green roof 2. How to select the type of green roofs you should employ on your project 3. The public and private benefits and costs of green roofs 4. The important technical issues which must be addressed 5. Maintenance issues which ensure longevity 6. Detailed cost variables for green roofs 7. The potential of green roofs through several case studies

1.0 BACKGROUND

Green roofs are not a new phenomenon. They have been standard construction practice in many countries for hundreds, if not thousands, of years, mainly due to the excellent insulative qualities of the combined plant and soil layers (sod). In the cold climates of Iceland and Scandinavia sod roofs helped to retain a building’s heat, while in warm countries such as Tanzania, they keep buildings cool. Canadian examples of early green roofs, imported by the Vikings and later the French colonists, can be found in the provinces of Newfoundland and Nova Scotia.

Two modern advocates of green roof technology were the architects Le Corbusier and Frank DESIGN GUIDELINES FOR GREEN ROOF Lloyd Wright. Although Le Corbusier encouraged rooftops as another location for urban green space, and Wright used green roofs as a tool to integrate his buildings more closely with the landscape, neither was aware of the profound environmental and economic impact that this technology could have on the urban landscape.

Until the mid-20th century, green roofs were viewed mainly as a vernacular building practice. However in the 1960’s, rising concerns about the degraded quality of the urban environment and the rapid decline of green space in urban areas, renewed interest in green roofs as a "green solution" was sparked in Northern Europe. New technical research was carried out, ranging from studies on root-repelling Fig. 2 – French Fisherman’s Cottage agents, membranes, drainage, lightweight Fort Louisbourg, Nova Scotia, Canada growing media, to plant suitability. Photograph courtesy of M. Kuhn

2 DESIGN GUIDELINES FOR GREEN ROOF on allnew flat-roofed industrialbuildings. requires green roofs for example, Stuttgart, now incorporateroof greening intoregulations. agl ysaelgsain municipal grantsandincentives of35-40DeutschMarks/m largely by statelegislation, Thisgrowth wasstimulated ballooningfrom onetotenmillionsquare metres. rate of15-20%, withanannual growth thegreen roof market expandedquickly inthe1980’s, In Germany, roof greened. group calledthe avolunteer More recently, Vancouver. Centre inSouthernOntarioandRobsonSquare in TheseincludetheBoyne River Education have helpedtoestablishthefirstgreen roofs. are someofthepeoplewho Allen andMarioKani, andengineersGreg Charles Simon, architects DougPollard and landscape architect CorneliaHahnOberlander, In Canada, tochange. Thishasstarted readily invest ingreen technologies. andgovernments donot businesses, cultural andpoliticalclimatewhere many individuals, especially ina andaccessibleexamples, localresearch ontechnicalperformance, education, thesystemswere However, hard tosellwithoutpublic American markets. into theNorth During theearly 1990’s several largeEuropean green roof manufacturers toventure started infrastructure asaviableoptionfor solvingmany qualityoflife challengesfacingourcities. Canada andtheUnitedStatesare atleasttenyears behindEurope ininvesting ingreen roof become acommonfeature intheurbanlandscape. andgreen roofs have hasbeencreated, anew sectorintheconstructionindustry result, Asa airandwaterqualityimprovements. public benefitsofstormwaterrunoffreduction, Akey hasbeenthe motivatorfor thissupport or requirements for green roof installation. Over 75European municipalities currently provide incentives ensure ongoing maintenance. installationand3years postconstructionto new green roofs atthestagesofplanning, Environment Canada , the City of Toronto, and Cityof the Environment Canada, oftheNationalResearchA partnership Council’s Institutefor Research inConstruction(IRC), research toshow thebenefitsofthistechnology. implementdemonstrationprojects andconducttechnical They provide information, for Healthy Cities extension amongothers. on theperformance ofgreen roofs inareas efficiencyandmembranelife suchasenergy IRC’s At Ottawa facilitiesaroof hasbeenretrofitted todeterminemore detailedtechnicaldata and Ottawa. Winnipeg, Portland, and demonstrationactivityisunderway inChicago, ofgreen Aflurry roof-related research of itsSopranaturein support green roof product. theroofing company Soprema isstudyingplantsurvivability At Laval University inQuebec, Toronto, includingthepublicly-accessibleresearch roof oftheCityHall. projects in (3) te uoensae aeaotdsmlrtpso upr.Several cities Other European stateshave adoptedsimilartypesofsupport. have beenworking todevelopAmerica. thegreen roof market inNorth Rooftop Gardens ResourceGroup (4) Vienna alsoprovides subsidiesandgrantsfor Green Roofsfor Healthy Cities and an industry group called and anindustry has spearheaded Green Roofs 2 of 3 1.1 INTENSIVE AND EXTENSIVE GREEN ROOFS

A green roof is a green space created by adding layers of growing medium and plants on top of a traditional roofing system. This should not be confused with the traditional roof garden, where planting is done in freestanding containers and planters, located on an accessible roof terrace or deck. The layers of a contemporary green roof system, from the top down, include:

• the plants, often specially selected for particular applications, • an engineered growing medium, which may not include soil, • a landscape or filter cloth to contain the roots and the growing medium, while allowing for water penetration, • a specialized drainage layer, sometimes with built-in water reservoirs, • the waterproofing / roofing membrane, with an integral root repellent, and • the roof structure, with traditional insulation either above or below.

The two basic types of green roof systems - extensive and intensive - are differentiated mainly by the cost, depth of growing medium and the choice of plants.

Extensive green roofs are often not accessible and are characterized by:

• low weight, • low capital cost, • low plant diversity, and • minimal maintenance requirements.

DESIGN GUIDELINES FOR GREEN ROOF The growing medium, typically made up of a mineral-based mixture of sand, gravel, crushed brick, leca, peat, organic matter, and some soil, varies in depth between 5-15 cm (2-6") with a weight increase of between 72.6-169.4 kg / m2 (16-35 lbs/sf) when fully saturated.(1) Due to the shallowness of the growing medium and the extreme desert-like microclimate on many roofs, plants must be low and hardy, typically alpine, dryland, or indigenous. Typically the plants are watered and fertilized only until they are established, and after the first year, maintenance consists of two visits a year for weeding of invasive species, safety and membrane inspections.(2)

Intensive green roofs are often accessible and are characterized by:

• deeper soil and greater weight, • higher capital costs, • increased plant diversity, and • more maintenance requirements

Fig. 3 – Mountain Equipment Co-op Toronto, Ontario, Canada Soprema System of Roofing, Curb, Drainage Layer, Filter Cloth and Bagged Growing Medium 4 Photograph courtesy of M. Kuhn The growing medium is often soil based, ranging in depth from 20–60 cm (8-24"), with a saturated weight increase of between 290 - 967.7 kg/m2 (60-200 lbs/sf). Due to the increased soil depth, the plant selection is more diverse and can include trees and shrubs, which allows for the development of a more complex ecosystem. Requirements for maintenance - especially watering - are more demanding and ongoing, and irrigation systems are usually specified. Structural and horticultural consultation and an experienced installer are recommended.

It should be noted that, depending on such site specific factors as location, structural capacity of the building, budget, client needs, and material and plant availability, each individual green roof will be different, likely a combination of both intensive and extensive systems. Table 1 summarizes the advantages and disadvantages of extensive and intensive green roof systems.

Table 1: Comparison of Extension and Intensive Green Roof Systems

EXTENSIVE GREEN ROOF INTENSIVE GREEN ROOF

• Thin growing medium; little or no irrigation; • Deep soil; irrigation system; more favorable stressful conditions for plants; low plant diversity. conditions for plants; high plant diversity; often accessible.

Advantages: Advantages: • Lightweight; roof generally does not require • Greater diversity of plants and habitats. reinforcement. • Good insulation properties. • Suitable for large areas. • Can simulate a wildlife garden on the ground. • Duitable for roofs with 0 - 30° (slope). • Can be made very attractive visually. • Low maintenance and long life. • Often accessible, with more diverse utilization • Often no need for irrigation and specialized of the roof. i.e. for recreation, growing food, as drainage systems. open space. DESIGN GUIDELINES FOR GREEN ROOF • Less technical expertise needed. • More energy efficiency and storm water • Often suitable for retrofit projects. retention capability. • Can leave vegetation to grow spontaneously. • Longer membrane life. • Relatively inexpensive. • Looks more natural. • Easier for planning authority to demand as a condition of planning approvals.

Disadvantages: Disadvantages: • Less energy efficiency and storm water • Greater weight loading on roof. retention benefits. • Need for irrigation and drainage systems • More limited choice of plants. requiring energy, water, materials. • Usually no access for recreation or other uses. • Higher capital & maintenance costs. • Unattractive to some, especially in winter. • More complex systems and expertise.

Source: adapted from: "Greenbacks from Green Roofs: Forging a New Industry In Canada," CMHC. 1998.

Fig. 4– Queen’s Quay Terminal Toronto, Ontario, Canada Green Roof Courtyard with Skylights Architect: Zeidler Roberts 5 Photograph courtesy of M. Kuhn DESIGN GUIDELINES FOR GREEN ROOF . PRIVATE /BUILDING OWNER BENEFITS 2.1 SELLING THE CONCEPT-BENEFITS 2.0 temperature drops below 0 studiesshow that30cm(12")ofgrowing mediumwillnotexperience growing mediafreezes, 2.1.1 ENERGY SAVINGS The following describessomeofthesellingpointsgreen roofs. clientandforsuccess isfindingtherightmixofbenefitsfor theirproject. aparticular thekey to Sinceeachgreen roof installationisunique, tests andtheuseofmodeling. America climatezonesthrough bothfield these are stillbeingqualifiedindifferent North Many of bothpublicandprivate. economicandenvironmental benefits, range ofsocial, One ofthemostvaluablefeatures ofgreen roof infrastructure isthatitgeneratesawide that green roofs costthesame orlessthanconventional roof systems. costing datawhichincludesthecostofdeferred maintenanceandreplacement suggests Life cycle Theseare direct operationalcostsavings for thebuildingowner. for landfill. andthusdecrease the needfor re-roofing and theamountofwastematerialbound roof, European evidence indicatesthatgreen roofs willeasily doublethelife spanofaconventional and accidentaldamagefrom pedestriantraffic. the negative impactofultraviolet radiation, Green roofs helptoprotect roofing membranesfrom extreme temperature fluctuations, ROOF MEMBRANE PROTECTIONAND LIFEEXTENSION 2.1.2 efficiency gainsofvariousgreen roof systemsondifferent buildingtypes. research isworking todevelop amodelthatwillmore accurately predict theenergy IRCandEnvironment Canada a reduction intherequirements for traditional insulation. theimplementationofagreen roof may alsoallow for Depending ontheclimatezone, summer have beenmodelled ashigh25%. savings thecoolingenergy inthe where theroof ofthebuildingenvelope, isalargeportion For exampleinoneortwo storey complexes factor indeterminingoverall costsavings. Buildingtypeisakey more substantialthanthevalueofadded insulation inthewinter. Modeling research suggeststhatthereduced needfor airconditioninginthesummeris thetypeofplantsandothervariables. and thedepthofgrowing medium, • itslocation, • thesizeofbuilding, • • impact isafunctionof: costsavings Theextentoftheenergy requiredthe amountofenergy toheatthebuilding. theadditional insulationprovided by thegrowing mediumhelpstodecreaseIn thewinter, cool thebuilding. aswell asdecreasing required theamountofenergy to helps tocoolthesurrounding area, Thisinturn ifnoteliminateany netheatgain. canreduce, process ofevapotranspiration, through the green roof plantingshadesthebuildingfrom solarradiationand, In thesummer, a thicklayer ofplants hasacombinedinsulative valueofRSI0.14(R20). o C (32 o ) vnwe usd eprtrsae -20 even whenoutsidetemperatures are, F), (5) A 20cm(8")layer ofgrowing mediumand (6) Even whenthe o(7) 6 i.5–Muti qimn oo,oot,Otro Canada Ontario, 5–Mountain Equipment Co-op,Toronto, Fig. DESIGN GUIDELINES FOR GREEN ROOF htgah oreyo .Kuhn of M. Photographs courtesy Toit vert ae otn,orasprinklerirrigation systemconnectedtothefire alarm. water content, whichhave ahigh suchassedums, options would betheuseof"fire retardant plants", Other andlocatedevery 40m(130feet) inalldirections. 60cm(24")wide, pavers, These breaks would bemadeofanon-combustiblematerialsuchasgravel orconcrete andaround allroof penetrationsisrecommended. attheroof perimeter, across theroof, theintegrationof"fire breaks" atregular intervals Similar topreventing grassfires atgrade, canpresent afire hazard. ifdry, theplantsthemselves, However, medium issaturated. where particularly thegrowing the spread offire toandfrom thebuildingthrough theroof, There isevidence from European manufacturers suggestingthatgreen roofs canhelpslow FIRERESISTANCE 2.1.4. 12 cm(5")ofgrowing mediumalonecanreduce soundby 40db. Tests show that andtheplantsblockinghigherfrequencies. lower frequencies ofsound, withthegrowing SOUNDINSULATION mediumblocking Green roofs canbedesignedtoinsulatefor sound, 2.1.3 process for new projects. residential areas hassignificantaestheticvalueandmay helptospeeduptheapprovals Even inaccessiblegreen spaceontopofcommercial buildingsin convention centre. Itsitsabove thegarageofnew Toronto. the new RoundhouseParkindowntown Cities. TorontoToronto CatholicSchoolBoard and Hydro Services, Energy Aproject todemonstratethistypeofapplication inunderdevelopment with classrooms. can integratecurricula andprovide added green spacefor students–outdoorrooftop Schoolboards aswell asimproving theirqualityoflife. space ontopofhousingprojects, accessiblegreen Public housingagenciescanprovide seniorcitizensandfamilieswithsafe, payers associations. andrate community members, planning approval for projects from localbuildingofficials, theinstallationofagreen roof may alsohelpgain of officeorresidential suitesfor buyers, Inaddition totheincreased marketability can helptoincrease theunitvalueofcondominiums. whichprovide added amenityspacefor theoccupants, accessiblegreen roofs, For example, dependingonwhichjurisdictionthebuilding islocatedinandtheoccupancy. green roof, There are many specializedapplications thatjustifyadditional capital expenditures for a 2.1.5 ADDITIONAL BENEFITS oenet eeaepbil cesbepr pc ntpo akn aae,like Governments generatepublicly accessibleparkspaceontopofparkinggarages, i.6–Rudos akTrno nai,Canada Ontario, Roundhouse park,Toronto, 6– Fig. Green roof at grade Green Roofsfor Healthy 7 DESIGN GUIDELINES FOR GREEN ROOF 2.2 PUBLIC BENEFITS city dwellers. andproviding new employment for opportunities ensuringripenessatharvest, field totable, reducing thetimeanddistancefrom reducing andrefrigeration associatedtransportation costs, Thishastheadvantageof andmedicinalornamentalplants. of highqualityorganicfoods, Green roofs are for theproduction alsobedesignedtogenerateurbanagriculturalopportunities whileatthesametimeactingasirrigation andnutrient source for theplants. roof, istreated inanon-sitesewagethe factory pondatgradeandthenfiltered through thegreen Effluentproduced by hasatwo-acre green roof withnative grassesandwildflowers. factory, Their1992 isaBelgianmanufacturer products. ofbiodegradablelaundry Ecover Inc. the roof. orsimply toimprove theaestheticsurroundings for buildingsthatoverlook for employees, toprovide amenity space Industrial buildingsincorporatespecializedgreen roofs for cooling, roofToronto. iscurrently plannedfor recovery theroof centre ofaheadinjury inNorthern therapy Ahorticultural green method ofspeedingrecovery ratesandreduction ofdruguse. aprovenHospitals andotherhealthcare facilitiesprovide therapy, for horticultural opportunities that itdoesnotproduce heat. Like urbanforests andreflective roofing surfacesthey absorband/ordeflectsolarradiationso thereby improving conservation. energy strike darkroof surfacesandbeconverted intoheat, Green roofs intercept thesolar radiationthatwould It alsoexacerbatesheat-related illnesses. increases therateatwhichchemicalprocesses generate pollutantssuchasground level ozone. The urbanheatislandeffect increases theuseofmore electricityfor airconditionersandit negative impactsonourquality oflife. temperatures have arangeofdirect andindirect highsummer Theseartificially the pastdecade. America have been ontheriseover North in summer temperatures Average andhard surfaceareas. built-over, paved, dueto surrounding countryside, relative tothe urban andsuburbanareas, URBANHEAT ISLANDEFFECT The urbanheatislandistheoverheating of 2.2.1 and improved the reduction ofthe ofthesepublicbenefitsaremost important Thetwo the publicbenefitsofthesesystems. for implementationare designedtopromote European incentives andlegislation benefits, Although green roofs provide many private storm water retention. urban heatislandeffect major citiesacross increased i.7–HzlunC-pTrno nai,Canada Hazelburn Ontario, Co-op,Toronto, 7– Fig. htgahcuts fM Kuhn ofM. Photograph courtesy Rooftop Garden 8 DESIGN GUIDELINES FOR GREEN ROOF roof) from couldcleanse4,000kg ofdirt theairperyear (2kg per m ertie nuly Thiswould eliminatecombinedsewage overflows by 17milliongallons. be retained annually. anestimated66million gallonsofwaterwould (219acres), downtown area hadgreen roofs, Oregon found thatifhalfofthebuildingsin retention studyfor theCityofPortland, suggests thatagrassroof with 2,000m (8-16") thickgrowing mediumcanholdbetween ofwater10-15cm(4-6"). Aheavily vegetated green roof witha20-40cm andrelief drainspacing. retention andflow, under-drainage layer porosity, water fieldcapacity, thicknessofthegrowing media, capacity, Stormwaterretention ratesare determinedby saturatedinfiltration and evapo-transpiration. Water stored inthegrowing mediaisreleasedcapture through andholdrainwater. evaporation Theplants STORM WATERGreen roofs canbedesignedforRETENTION exceptionalstormwaterretention capability. 2.2.2 coal fired utilities. andhelpoffsettheproduction ofsulphurdioxides from nitrous oxides andsmog, level ozone, Thecoolingwould alsoslow thechemicalprocesses thatproduce ground buildings inChicago. yield savings of$100,000,000annually from reduced coolingloadrequirements inallofthe thiswould (30%ofthetotallandarea), buildings inChicago were retrofitted withgreen roofs, allofthe over aperiodoftenyears ormore, Thestudysuggeststhatif, use. in coolingenergy that every onedegree Fahrenheit decrease inambientairtemperature results ina1.2%drop ASHRAE simulation conductedby theCityofChicago oftheirCityHallgreen roofAn showed should never beconsidered asajustificationtodestroy naturalhabitatatgrade. althoughthey CREATIONGreen roofs OFHABITAT canbedesigned asacceptablealternative habitatsfor some species, 2.2.4 pollution countoflessthanathird ofthatamount. perlitre particles ofairandatreed10-20,000 dirt street inthesameneighborhoodhadanair a street withouttrees had anairpollutioncountof for example, Germany, In Frankfurt and sequesterthemintheirleaves (latertobecomehumus). Plantsalsoabsorbgaseouspollutantsthrough photosynthesis into thegrowing mediumbelow. Rainwashesit tendtogettrapped inthesurfaceareasAirborne particulates ofthegreenery. matterastheairpassesover airborneparticulate theplants. AIRCLEANING Green roofs alsofilteroutfine, 2.2.3 provided that60%oftheroof area isgreened. installed, incentive whichawards adensitybonus of3square feet for every square foot ofgreen roof Oregon hasrecently adoptedan Portland, American cities. considered inseveral North Thistypeofmeasure isbeing reduction instormwaterchargesfor green roof installations. 13municipal governments allow for a InGermany, in direct andindirect financialincentives. thisabilitytoretain stormwatermay result requirement for stormwatermanagementponds, ora zero runoffpolicies, Where jurisdictionsdemandlot-level stormwatercharges, The studyindicatedthatstormwaterdischargeswould bereduced between 11and15%. streets have 10-15%fewer thanfound thansimilarstreets dustparticles withouttrees. selected plant varietieswhoseseedsare notspread by air orover distances. short Thistypeof habitat would behometo habitat thatremains isolated from habitatatgrade. Thesecondisan"island" airborneseeds). insects, be by aironly (nesting andmigratingbirds, to remember Itisimportant thatthisconnectioncan isolated habitatpockets witheachother. Thefirstisa"steppingstone"habitatthatconnects natural of wildlife corridors in urbanareas. ofalargersystem aspart two typesofgreen roof habitatshave beendefined andimplemented, grass roof couldstilltake every year. outthesignificantamountof2kgdirt ihtear oee,ee fteaon ee11t fwa re ol eoe 10m even iftheamountwere However, 1/10thofwhattrees couldremove, with theair. is probably highsincethelower ofthegrasslayer portion istoodensetobeindirect contact (8) 2 of unmown grass(100m (13) ae ndt rmtes one estimate Based ondatafrom trees, (11) Studies show thattreed urban 2 of leafsurfaceperm 2 fro) Thisestimate, of roof). (9) A storm-water (14) (15) In Europe, (12) 2 2 of of (10) 9 DESIGN GUIDELINES FOR GREEN ROOF 3.3 CONSULTANTS 3.2 LOCATION 3.1 USE DESIGN&IMPLEMENTATION CONSIDERATIONS 3.0 net swl.Thedeeperthesoilmore insectdiversity thegreen roof willsupport. insects aswell. itbecomesasafer habitatfor on aninaccessiblegreen roof isalsolesslikely tobedisturbed, Sincethesoil andtobirds speciesthatonly nestontheground. easily damagedby walking, are more protected andcanbecomehometosensitive plantsthatare human intervention, Island andtheGreat Lakes RegioninCanada. including theprairiegrasslandsofmidwest UnitedStatesortherocky alvarsofManitoulin Green roofs canalsobespecifically designedtomimicendangered ecosystems/habitats, ofn oslat lne;a rit andmarketing /advertising professionals. anartist; aplanner; a roofing consultant; anecologistorbiologist; therapist; ahorticultural consultants may alsoincludeahorticulturalist; specialist function ofthegreen roof, Dependingontheprimary equipment anddrainageneeds. andtodiscuss integrationwithexistingandproposed rooftop mechanical of thegreen roof, Amechanicalengineermay berequired tocalculatetheheatingandcoolingimplications plants. landscape architect may berequired for thelayout ofthe plantingareas andtheselectionof A includingmaterialspecifications. as well asthedesignanddetailingofbuildingroof, Anarchitect may be required toco-ordinate theproject loading capacity oftheroof. required, or Astructuralengineermay berequired todeterminetheexisting, and /orproject instigator. andthegreen consultant roof experienceoftheprimary thelocationofproject, project, thesizeof Selection ofprofessional consultantsdependsonthefunctionofgreen roof, also determinewhere elementsare certain locatedfor maximum effect. Views toandfrom theroof may specific microclimate ontheroof must alsobeconsidered. Thegeneralclimateofthearea andthe ofthedaybuildings duringparts willhave animpact. theroof’s orientationtothesunand shadingby surrounding itsexposure towind, above grade, Theheightoftheroof Location ofthegreen roof plays role animportant inthedesignprocess. concentrate thefocus ononeoranotherofthesefunctions. may amongothers, butlimitingfactorsinthebudgetorbuildingstructure, both, itcanbe Indeed, to retain stormwatercannotorshouldnotalsobeaesthetically pleasing. Thisisnottosay thatagreen roof designed andoverall cost. ongoing maintenanceprogram, the question ofaestheticsare inherent differences intherequired depthofgrowing medium, Alongwiththe different from onewhosemainpurposeistobrighten ahospitalcourtyard. agreen roof designedtoretain stormwatermay lookvery For example, on itsoverall design. functions aspecificgreen roofThe primary isrequired toperform willhave aprofound effect fromproject thenext. willvary soeachindividualgreen roof andeachenduserisdifferent, eachbuildingowner, each building, Itshouldbenotedthatjustaseachsite, the following issuesare considered anddealtwith. provided The designandimplementationofagreen roof project isrelatively straightforward, (16) xesv re of,withtheirlackof Extensive green roofs, 10 DESIGN GUIDELINES FOR GREEN ROOF 3.5 STRUCTURE 3.4 THE REGULATORY APPROVALS PROCESS proceeding withaproject. from provincecodes vary toprovince soyou shouldcheckthespecificrequirements priorto Building background information andtestreports from product manufacturers andsuppliers. alongwithapackageof application for permitwilloftenrequire aneducationcomponent, soan letaloneapproved theplansfor one, havedepartments never heard ofthisconcept, Many oftheplansexaminersatvarious building it conforms tothebuildingcode. This isnottosay thatagreen roof project willbeacceptedwithoutquestionprovided that andbarrier free access. guardrails, lighting, exiting, comply withrequirements for occupancy, or thepublicuseroof asanaccessibleoutdoorgreen space-thenthedesignmust also iftenants If thegreen roof isaccessiblefor more thanroutine maintenance-inotherwords, and therefore must comply withrequirements for structuralloadingandmoisture protection. green roof systemsare considered anextensionoftheroof system, National BuildingCode, Although they are notspecifically mentionedinthe1997OntarioBuildingCodeor different andshouldbeinvestigated withlocalplanningandzoningofficials. Pleasenotethattheregulations withineachmunicipality are sensitive community groups. roof may beusedasaconsiderationonenvironmentally sensitive sitesorwith environmentally aproposed green Inthemeantime, credits for retention ofstormwaterrunofffrom thesite. orasource ofyearly tax green roofs may becomearequirement buildingtypes, for certain Inthefuture, withnolossofgross floorarea withinthebuildingenvelope. for thatbuilding, itmay alsoqualifyasanamenityspace Ifthegreen roof isaccessibletotenants, density bonus. ortoqualifyfor a This couldpermitthedeveloper tousemore oftheproperty atgrade, Local planningandzoningmay qualifyagreen roof asgreen spaceorlandscaped openspace. dependingonthesitelocationandoccupancyofbuilding. percentage ofgreen space, oftenrequires acertain for anew buildingorinaretrofit situation, Development ofaproperty, loading required only inspecificareas on the roof whichare subject todriftingandbuild-up. withcapacity for highersnow 40lbs inearliereditions)must beaccommodatedontheroof, a generalsnow loadofonly 107kgper square metre (22lbs/sfdown from Toronto, In areas like Recent editionsoftheOntario BuildingCodehave changed requirements for snow loading. beyond thestandard requirements oftheBritishColumbiaBuildingCode. per square metre (60lbs/sf)whenfully saturatedanddidnotrequire structuralupgrading Thisweighs only 292.6 kg andcompost. pumice, layer oflightweight substratemadeupofsand, (14") hasa35.6 cm. Canada, BritishColumbia, Vancouver, The green roof in onthenew library green hasresponded roof by industry developing varioustypesoflightweight growing media. The whichincludesthesnow load. of only 40lbspersquare foot (195kgpersquare metre), existing roofs are typically designedfor alive load Canada, consideringthat in Ontario, is alot, This Typical wet soilweighs approximately 1,597kgpercubicmetre (100lbspercubicfoot). investment. whichcanbeasignificant unlesstheowner isprepared toupgradethestructure, existing roof, capacity ofthe thedesignwillbelimitedtocarrying installed onanexistingbuilding, ifagreen roof However, is loading canbeaccommodatedeasily andfor arelatively minorcost. theadditional Ifagreen roof ofthe initial designofthebuilding, ispart green roof installation. Additional loadingisoneofthemainfactorsindeterminingbothviabilityandcosta (17) 11 This leaves 88 kg per square metre (18 lbs/sf) for a green roof installation, - enough for a simple extensive system. On inverted roof applications, where the waterproofing membrane has been applied underneath the loose-laid insulation and a layer of ballast, usually gravel or concrete pavers, the green roof can be used to replace the ballast, thereby effectively allowing an increase in the load bearing capacity of the roof by eliminating the dead load of the ballast material. A thorough analysis of the roof structure may also reveal areas where point loading can be increased - perhaps over a column or along a bearing wall, thus allowing for a combination extensive and intensive system (semi-extensive), with specific areas for deeper growing medium and larger plants. Please note that owners, tenants, and building managers should be made aware of the roof’s loading restrictions, through a plan or as a part of a maintenance manual, to avoid future improper relocation or additional plantings in areas which cannot accommodate the weight.

3.6 ACCESS AND EXITS

Access to the green roof site is crucial - not only for installation and ongoing maintenance, but also for bringing up materials, soil and plants. With a new building, the design of internal stairs or an extra elevator stop in the planning stages is easy and relatively inexpensive; to retrofit an existing building can become costly. Where an elevator does not go to the roof, material will have to be transported by hand up stairs and utility ladders, or hauled up with a crane, both of which can result in additional labour and equipment costs. An interior ladder or staircase may be safer than one attached on the outside of the building, and access through a "man door" is preferable to a small roof hatch. If the green roof is designed for use by tenants or the general public, then questions of access and of exiting are taken to another level altogether, from mere convenience to strict standards of safety and security as regulated by the local Building Codes.

3.7 ROOFING

DESIGN GUIDELINES FOR GREEN ROOF One of the most important components of the green roof system is the waterproofing/roof membrane. For an existing building, the membrane should be carefully inspected to determine if it needs to be repaired or replaced before the installation. Many manufacturers of green roof systems will not provide a warranty on the green roof system if new membranes are not applied. The normal 10-15 year reroofing cycle provides a window of opportunity to investigate the potential of applying a longer lasting green roof. Green roofs can be applied on inverted or traditional roofing systems. If the existing system is inverted, then one needs to determine whether the insulation can be replaced by an equivalent R- value of growing medium. If the insulation is to remain, then good drainage must be ensured to prevent continuous contact with water, and subsequent damage.

300 - 500 mm

Styrofoam

Soil

Fig. 8 – Deep Soil over Structural Column Fig. 9 – Gravel Skirt and Vegetation Barrier Around Roof Drain Illustrations courtesy of R. Hippolite, based on Grundlagen der Dachbegruenung, Patser Verag, Berlin, 1989. 12 lutaincuts fR iplt,bsdo rnlgndrDcbgunn,Pte ea,Bri,1989. Patser Berlin, Verag, based on Grundlagen der Dachbegruenung, Hippolite, ofR. Illustration courtesy 10 – Fig. DESIGN GUIDELINES FOR GREEN ROOF Flashing andGravel Barrier with Drainage Pipe ata Wall/Roof Connection ≥ ≥ 150 mm 500 mm 3.8 PLANTS been designedby somegreen roof manufacturing companiesspecifically for thisapplication. gridsystemsfor green Support roofs have orloose-laidontop. either underthemembrane, placed or metal, plastic, wood, This canbeprevented through theuseofhorizontalstrapping, especially whenitbecomeswet. or plantlayer doesnotsliporslumpthrough itsown weight, the green roof installerneedstoensure thatthesod On aroof slopegreater than20degrees, causingtheplantstodrown Thegrowing orrot. mediumitselfmay sour, medium. duetocontinuous contactwithwaterorwet leakageofthemembranemay occur, blocked, Ifthedrainagelayer istoothinoriftheroutes totheroof drainsbecome a weeping drainpipe. andchimneys must bewell protected withagravel andsometimes skirt vents, mechanical systems, androof penetrationsmadeby skylights, flashing, edges, Parapets, on theroof important. isstillvery maintainingproper drainage Although thegreen roof willretain much oftherainthatfallsonit, be compatiblewiththesystemcomponentswhichitwillindirect contact. Thechemicalmakeup ofthemembranemust also joint/seam linestoprevent root damage. now containaroot-deterring chemicalormetalfoil between themembranelayers andatthe althoughstillbituminous, new membranesdeveloped specifically for green roof applications, Someofthe membrane willbesusceptibletoroot penetrationandmicro-organic activity. sincethe to maintainacontinuous separationbetween themembraneandplantlayer, itiscrucial containsbitumenorany otherorganicmaterial, existingornew, If themembrane, ihfwecpin,thechoicesare limitless. with few exceptions, Onanintensive green roof, andalpine slopes. alvars, tundras, andwildflowersplants thatare native - todrylands, irises, festucas, sempervivums, sedums, mosses, rely onamixture ofgrasses, Typically, extensive green roofs ones ontheroof toensure theirabilitytoadapt andflourish. where theplantswere previously grown andifthegrowing conditionswere comparabletothe Itisvitaltoknow the plantwillstabilizein10cm(4")or60(24")ofgrowing medium. Rootsizeanddepthshouldalsobeconsidered indeterminingwhether of grassesandsedums. thechoiceofplantingmaterialshouldbelimitedtohardier orindigenousvarieties fertilization, and irrigation, Unless oneiswillingtoprovide shadingdevices, on arooftop are oftenextreme. Climaticconditions inthefirsttwo particularly years whenthey are gettingestablished. project, roof isdirectly proportional totheamountofmaintenancetimeandbudgetallocated onagreen Theabilityofplants tosurvive andsoildepthare allfactorsin determining whatplantscanbegrown andwhere. shade, buildingheight, airpollution, rainfall, wind, Location, 3.9 CONSTRUCTION/INSTALLATION oeta qimn etl.Timingisalsoimportant. potential equipmentrentals. to theroof shouldbediscussedtodeterminecostand getting thematerials up Methodsfor post-construction. Itwillalsobringsinglepointresponsibility various trades. scheduling conflictsanddamageclaimsbetween the thusavoiding from re-roofing toplanting, project, be preferable tohave onecompany handle thewhole itmay Infact, have experiencewithgreen roof systems. Theinstallersshould Be aware ofinstallationissues. 13 DESIGN GUIDELINES FOR GREEN ROOF 3.11 INSURANCE&LIABILITY 3.10 MAINTENANCE up thewholeinstallation. withouthaving topull for inspectionandmaintenance, to themembraneandroof drains, ofthegreen Compartmentalization roof intosectionsmay allow for easieraccess problem. Covering theroof withburlap orsomeothermaterialcouldreduce this wind andrunoff. the fallfor springplantingthere may besomeerosion ofthegrowing mediumthrough winter Ifyou prepare everything in Someplantscanbeinstalledwhiledormant. cold weather setsin. of suitableplantstockandtimeenoughtoallow for theplantstogetestablishedbefore the Fallplantingwilldependontheavailability plants through theheatbefore they are established. plantinginhighsummerrequires extrairrigation togetthe Depending onthelocalclimate, illkl erltdt h ntlainisl,andnottheperformance of the products. will likely berelated totheinstallationitself, thentheonly warranty orguaranteeavailable for this"combiningofproducts" If costisaconcern, perform thesamefunctionbutwere not specifically designedfor useinagreen roof applications. though thepriceistypically higherthancombiningindividual products which “off-the-shelf” even especially institutions, This senseofsecuritycanbeasellingfeature for someclients, warranty for theirproducts aslongthey are installed asperthemanufacturer’s specifications. Allmanufacturers ofgreen roof products willprovide a accessible for tenantorpublicuse. unlessitismade Building insuranceshouldnotincrease withthe addition ofagreen roof, become more convincing. medium andplants, withnew growing fresh, andthearguments for starting costswillincrease accordingly, back up, andthenbrought ifthegreen roof hastobemoved offtheroof, to theoriginalinstallationcost; andcomparable thentheadditional costis"labour"only, membrane isbeingreplaced insections, Ifthegreen roof canberemoved andstored ontheroof whilethe or replaced entirely. thesystemwilleitherberemoved andreinstalled over thenew membrane, of growing medium, anddepth typeofplanting, buildingheight, Dependingontheroof size, will have tobereplaced. themembrane after30-50years, Eventually, roof for easeofremoval. intodistinctcompartments anddividingthegreen etc), sensitive areas free ofplantsandgrowing medium(gravel skirts, Accessstrategiesincludekeeping the membrane topinpointtheexactlocationofwaterleaks. the incorporationofanelectronic leakdetectionsystembetween orunderneaththewaterproofing Somecompaniesare recommending especially justbefore thewarranty periodexpires. installation, Regularmaintenanceinspectionsshouldbescheduledasfor astandard roof material failure. duemore tosloppy installationthanto andflashings, penetrations, can stilloccuratjoints, leaks doublingitslifespan, protects themembranefrom puncture damageandsolarradiation, Although thegreen roof fact thatthegreen roof systemcompletely covers themembrane. Maintenance andvisualinspectionsofthewaterproofing membranecanbecomplicated by the due tothegreater diversity ofplants. Intensive systemstypically require more maintenancethanextensive systems or toanaffiliate. andthatmaintenancecontractsbeawarded tothecompany thatinstalledthegreen roof, price, recommended thatthefees for three tofive beincludedintheoriginalbid years ofthisservice To itis ensure continuity inthe warranty andtheupkeep, andreplanting. pruning, for irrigation, toweekly visits will rangefrom two tothree yearly inspectionstocheckfor weeds ordamage, required plantmaintenance Depending onwhetherthegreen roof isextensive orintensive, Both plantmaintenanceandofthewaterproofing membraneare required. 14 4.0 DETAILED COST ESTIMATES AND VARIABLES

Although all green roof systems share common components, there are no standard costs for implementation. The two tables below give a range of component costs and identify some of the key variables that determine those costs.

4.1 INACCESSIBLE EXTENSIVE GREEN ROOF

(Costs assume an existing building with sufficient loading capacity; roof hatch and ladder access only. The larger the green roof, the cheaper the cost on a square metre basis.)

Component Cost Notes & Variables

a) Design & Specifications 5% - 10% of total roofing The number and type of consultants project cost. required depends on the size and complexity of the project.

b) Project Administration & Site 2.5% - 5% of total roofing The number and type of consultants Review project cost. required depends on the size and complexity of the project.

c) Re-roofing with root-repelling $100.00 - $160.00 per sm. Cost factors include type of membrane ($10.00 - $15.00 per sf.) existing roofing to be removed, type of new roofing system to be installed, ease of roof access, and nature of flashing required. DESIGN GUIDELINES FOR GREEN ROOF d) Green Roof System $55.00 - $110.00 per sm. Cost factors include type and (curbing, drainage layer, filter ($5.00 - $10.00 per sf.) depth of growing medium, type cloth, and growing medium). of curbing, and size of project.

e) Plants $11.00 - $32.00 per sm. Cost factors include time of year, ($1.00 - $3.00 per sf.) type of plant, and size of plant - seed, plug, or pot.

f) Installation / Labour $32.00 - $86.00 per sm Cost factors include equipment ($3.00 - $8.00 per sf.) rental to move materials to and on the roof (rental of a crane could cost as much as $4,000.00 per day), size of project, complexity of design, and planting techniques used.

g) Maintenance $13.00 - $21.00 per sm Costs factors include size of ($1.25 - $2.00 per sf) project, timing of installation, for the first 2 years only. irrigation system, and size and type of plants used.

h) Irrigation System $21.00 - $43.00 per sm. *Optional, since the roof could be ($2.00 - $4.00 per sf). watered by hand. Cost factors include type of system used.

15 DESIGN GUIDELINES FOR GREEN ROOF . ACCESSIBLE INTENSIVEGREENROOF 4.2 i) h) g) f) e) d) c) b) a) Maintenance Installation /Labor Guardrail /Fencing Irrigation System Plants and walkways) decking growing medium, filtercloth, drainage layer, Green RoofSystem(curbing, membrane Re-roofing withroot-repelling Review Administration &Site Project Design &Specifications h agrtegenro,thecheaper thecostonasquare metre basis.) The largerthegreen roof, roof hatchandladder accessonly. (Costs assumeanexistingbuildingwithsufficientloadingcapacity; Component ($1.25 -$2.00persf)annually. $13.50 -$21.50persm ($8.00 -$18.00persf.) $85.00 -$195.00persm. ft.) ($20.00 -$40.00perlin. $65.00 -$130.00perlin.m. ($2.00 -$4.00persf.) $21.00 -$43.00persm. ($5.00 -$200.00persf.) $54.00 -$2,150.00persm. ($15.00 -$30.00persf.) $160.00 -$320.00persm. ($10.00 -$15.00persf.) $100.00 -$160.00persm. project cost. 2.5% -5%oftotalroofing project cost. 5% -10%oftotalroofing Cost of plantsused. andsizetype irrigation system, Costs factorsincludesizeofproject, andplantingtechniquesused. design, complexityof sizeofproject, roof, rental tomove materialstoandon Cost factorsincludeequipment project /lengthrequired. andsizeof attachment toroof, Cost factorsincludetypeoffencing, system usedandsizeofproject. Cost factorsincludetypeof between $200.00-$500.00. accommodated (onetree may cost suitable tothelocalclimatecanbe anysince virtually typeofplant the typeandsizeofplantchosen, Cost iscompletely dependenton include freestanding planterboxes.) (costdoesnot and sizeofproject. typeofdecking, height ofcurbing, typeand of growing medium, Cost factorsincludetypeanddepth nature offlashingrequired. and easeofroof access, installed, type ofnew roofing systemtobe existing roofing toberemoved, Cost factorsincludetypeof complexity oftheproject. required dependsonthesizeand The number andtypeofconsultants complexity oftheproject. required dependsonthesizeand The number andtypeofconsultants Notes & VariablesNotes & 16 DESIGN GUIDELINES FOR GREEN ROOF 6.0 CONCLUSION/RESOURCES 5.4 AESTHETIC BENEFITS OPENSPACE REQUIREMENTS 5.3 5.2 ENERGY EFFICIENCY 5.1 STORMWATER MANAGEMENT PUBLICINCENTIVESFORIMPLEMENTATION 5.0 erqie,thereby saving valuablelandfor otherpurposes. be required, green roofs can help toreduce thesizeofpondsthatwould normally developments, In jurisdictionsthatrequire theconstructionofstormwatermanagementpondsfor new storm waterdrainagesystemsare atcapacity orthearea hasacombinedsewer system. inareas particularly where thesewer/ storm waterrunoffispermittedinre-developments, no Inotherjurisdictions, to developers orbuildingowners whoretain stormwateronsite. ormay provide financialincentives Some jurisdictionsmay reduce waterandsewerage charges, considerably by jurisdiction. vary Thesewill of avenues describedbelow thatmay beworth pursuingonbehalfofyour client. there are anumber Despitethis, requirementsAmerica. regulatory for green roofs inNorth American publicpoliciesprovide direct financialincentives few or North Unlike Europe, eosrt h aybnft fti ehooy includinglifestyle benefitsamenities. demonstrate themany benefitsofthistechnology, there are many toimplement green nicheopportunities roof systemsand tohelp Until then, private buildingowners to undertake theadditional capital costsassociatedwiththesesystems. they willincreasingly looktoproviding incentives for many ofthechallengesfacingcities, recognize thewiderange ofpublicbenefitsgreen roofs andhow they can helptoaddress Asmore governments cometo with the variablesdeterminingcosts. needs oftheclient, Eachgreen roof systemshouldbetailored tothespecific therapy andeven food production. horticultural publicparkland, private"roofparks" for condominiumowners, inschools, opportunities building’s occupantsortothegeneralpublicwithbenefitsranging from enhancededucational Accessiblegreen roof systemscanconfer significantadded valuetoa aesthetic improvements. and soundinsulation, storm watermanagement, often wastedroof efficiency, spacesfor energy Green roofs are aproven thatprovide technology toutilize buildingowners withopportunities a green roof systemanddesigningitspecifically for maximum aestheticenjoyment. by incorporating reduce publicoppositiontoaproject, to speedtheapprovals process or, there may beopportunities In alocationwhere many buildingslookdown uponaroof, the localauthorities. a bargainingtoolfor additional densityorotherdesired features thatmust benegotiated with orprovide Green roofs may provide satisfytheseconditions, tosatisfyorpartially opportunities the developed property tobelandscaped openspaceand/orpublicly accessiblegreen space. many jurisdictionsrequire percentage acertain of Under theplanningactandzoningby-laws, reductions willberequired. Calculationofincreased Rvaluesandresulting energy as found inthelocalbuildingcode. efficiencies beyondimplementation oftechnologiesthatgenerateenergy aminimum standard, Some governments have programs thatprovide for theidentificationand financialsupport 17 DESIGN GUIDELINES FOR GREEN ROOF vriw ThisinaccessiblegreenToronto roof garden locatedondowntown corporate Overview: CANADA TORONTO, ONTARIO, MOUNTAIN EQUIPMENTCO-OP, 7.0 CASE STUDIES rvr:Someitemsinthe program StoneKohnVogtArchitects, McQuire (SKMV) Drivers: Top Nature Landscape Contractor: Ltd. Keen EngineeringCo., Ltd. Architect: Mechanical Engineer: ReadJones Christopherson, Structural Engineer: MountainEquipmentCo-op Installationofthegreen roof tookplaceinMay 1998andthebuilding Partners: Construction: Owner: o oeifraino re of,pleasevisitthefollowing web sites: For more information ongreen roofs, CMHCofficialweb site: • RooftopGardens Resource Group • Green Roofsfor Healthy Cities • a densityof14plants/m plantationat of sunflower seedsandperennial plants(containedin4inchpots, Thevegetation isawildflower meadow mix SOPRAFLOR-X growing medium. a Soprema andSoprema SOPRAFILTRE filter, SOPRADRAIN PSEfor drainage, Thegreen roof usesSoprema full sunexposure andaloadcapacity of40PSF. surrounds askylightlocatedonthesecondfloorofbuilding.Theroof has headquarters of of headquarters contributed tothis. issues andthegreen roof has debate aboutenvironmental to encouragediscussionand The buildingwasintended and community leadership. they contributedtosocial buttotheowner benefit, had noquantifiableeconomic Ferris +Quinn(withrecommendations from Architect: Landscape Winter 1998. was constructedduringFall1997- Buildings Innovation Greenbacks from Green RoofsReport. Technical Series: Research Highlight: www.cmhc-schl.gc.ca/en/burema/himu/buin/buin_009.cfm www.cmhc-schl.gc.ca/publications/en/rh-pr/tech/01-101_e.pdf www.interlog.com/~rooftop/ www.greenroofs.ca h onanEupetC-p The903m the MountainEquipmentCo-op. 2 ai-neBii fSpea Inc.) Marie-Anne BoivinofSoprema, ). i.11–MountainEquipmentCo-op Fig. oot,Otro Canada Toronto, Ontario, Soprema Green RoofInstallationandPlanting htgahcuts fM Kuhn ofM. Photograph courtesy 2 green roof area 18 i.12– VancouverFig. Green Roof Public Library DESIGN GUIDELINES FOR GREEN ROOF Photograph courtesy of Hydrotech Photograph courtesy acue,BiihClmi,Canada British Columbia, Vancouver, rvr:Environmental and aestheticpurposes Associates and, MosheSafdieand Drivers: Jackway Landscaping Architects: Landscape Contractor: CorneliaHahnOberlander Architect: Landscape Vancouver City of Buildingandgreen roof were constructedin1995 Partners: Construction: Owner: vriw This extensive 2400m Overview: Designtoprovide Includegreen roof inoriginaldesignscopetocutcosts. CANADA VANCOUVER PUBLICLIBRARY, BRITISH COLUMBIA, Itwill also Thegreen roof doeshave environmental andcommunity benefits. Changes: $55,000 $115,000andstructuralupgrade: Labourandmaterials: Benefits: Thepossibilityofadded costsofstructuralredesign allowing for employee Cost: Barriers: at,sandandpumice. waste, lightweight growing mediumwhichiscomposedofreconstituted vegetable green andblue/green tuftedfescues are plantedina different typesoftrees, Four Itisorientedtoward thecityandharbour. top the7storey library. Theinaccessibleroof islocatedon surrounding downtown officetowers. limited accessby employees for added benefit. Localdevelopers are consideringsimilarinitiatives. etc.). insects, butterflies, Successfulintheestablishmentofvegetation andwildlife (birds, medium. have ofmassgrowing someoperatingcostbenefitduetothermalinertia into thedesign. accessibilitywasnotincorporated upgradedtoaccommodatelivefurther loads, Sincetheroof structure would have hadtobe accessibility were barriers. Downs Archambault &Partners Downs 2 eeis Thegreen roof wasagreat success Total green roof costoflibrary : Benefits: None Cost: Barriers: green roof in Vancouvergreen roof in canbeviewed from but noquantifiabledatacollected approximately $250,000($104/sm.) 19 DESIGN GUIDELINES FOR GREEN ROOF eeis Thegreen roof provides for publicandprofessional anexcellentopportunity Total which costofgreen roof andreroofing wasapproximately $265,000, Benefits: Many constituencieswere involved andneededtobeaccommodated Technical Needfor research onperformance anddemonstration Cost: Barriers: Environment Canadaandthemembercompaniesof Drivers: Toronto, IRC, Cityof Julien Marton Landscape Architect: Toronto TheCityof Re-roofing andgreen roof were constructedinthefallof2000 Partners: Construction: Owner: Thisdemonstrationproject islocatedonthefirstfloorpodiumroof ofthe Overview: CANADA. ONTARIO, CITY HALL,TORONTO, R uligSine,Seia usre,Soprema andGarland) SheridanNurseries, IRC BuildingSciences, access toavarietyofdifferent typesofapplications inoneplace. to bereplaced in2004. Torontoof paidfor thevalue oftraditionalre-roofing whichwasscheduled TheCity Fund andthefederal government’sAction Fund. Climate Change Toronto the Atmospheric was shared by Green Roofsfor Healthy Cities, in order toimplementthegreen roof. Green Roofsfor Healthy Cities The eightplotsinclude: and Soprema. Two green roof systemswereroof manufactured applications. by Garland Itfeatures eightdifferent plotsthatrepresent avarietyofgreen thepublic. to Thegreen roofToronto isaccessible West. CityHallbuildingat100QueenStreet ra giutrlpos oneofwhichdemonstratessome ofthe 2urbanagriculturalplots, 2extensive green roof plotsdemonstratingawidevarietyofplants • • Abird andbutterfly garden withamixture ofnative and • Reproduction ofthenow rare blackoaksavannah prairie • 2semi-extensive systemsdemonstratingavarietyofplanttypes • principles andplanttypesassociatedwithpermaculture non-native material ecosystem typewithnative plantsdrawn from nearby HighPar and landscaping techniques FynCnd,Deboer Environmental Concepts, (Flynn Canada, 20 DESIGN GUIDELINES FOR GREEN ROOF ENDNOTES 7 hmsn 98 .4,inGBGR. 49, p. 1998, Thompson, 17. 1996. andReid, 1998; WetlandAmerican Engineering, North 16. inGBGR. 49, p. 1996, Johnston, 15. 11. p. ibid., 14. inGBGR. 11, p. 1982, Minke, 13. inGBGR. 10, p. 1996, Johnston, 12. inGBGR. 11, p. 1982, Minke, 11. Analysis An "Greening OurCities: C., andPeters, K. Liburdy, S.; Jones, S.; Beckman, 10. Prepared for CityofChicago FinalReport", "UrbanHeatIslandInitiative PilotProject: 9. 30. p. GBGR, 8. ANew Methodfor Controlling UrbanRunoffinUrbanized "Vegetative RoofCovers: 7. Forging aNew Industry "Greenbacks from Green Roofs: Peck S., M., Kuhn, B., Bass, 6. Adaptation andImpactsResearch Group, Environment Canada, BradBass, Dr. Com. Pers. inGBGR. 48, 5. p. 1996, Johnston, 4. inGBGR. 1992, Boivin, in"Greenbacks from Green Roofs"(GBGR)seebelow. 49, 3. p. 1998, Thompson, 2. 1996–marketing information. Soprema RoofingInc., 1. lnigWrso,19,p 26. p. 1997, Planning Workshop, Portland StateUniversity, Associated withGreen Roofs". of theBenefitsandBarriers 2000. May 9, al., Westonby et. Roy F. October1998.) Villanova University, Miller. C. Areas", –seefor apdffileofthereport. 24. 1998p. CMHC. in Canada"(GBGR), 2001. February 21 DESIGN GUIDELINES FOR GREEN ROOF Q&A’S association’spage. Web pleaserefer toyour professional For theanswers tothesequestions, 0 Whathappens tothegreen roof systemwhenthewaterproofing membrane 10. Cangreen roof systemsbeinstalled onaslopedroof? 9. Whatare three reasons tocreate aseparationbetween theplantsandany roof 8. Why isitrecommended toseparatethegrowing mediumfrom thewaterproofing 7. Whichareas withintheOntarioBuildingCoderegulate green roof systems? 6. Whatare theadvantagesofincludingagreen roof inthedesignphase ofaproject, 5. Whatare thesocialbenefitsfor buildingoccupants? 4. Whatare thecostsaving benefitsfor buildingowners anddevelopers? 3. Whatare theenvironmental benefitsofgreen roof installationsfor municipalities? 2. Why are theongoing maintenancerequirements for extensive green roofs different 1. reaches theendofitslife cycle? penetrations? membrane? rather thaninaretrofit situation? from thoserequired for intensive green roofs? 22