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END-OF-SERVICE LIFERECY CLING OF

THERMOPLASTIC ROOF

ASSEMBLIES

STANLEY P. GRAVELINE

SIKA SARNAFIL

CANTON, MA

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ABSTRACTMunicipalities are increasingly limiting the disposal of construction waste. As roofingmaterial makes up a significant part of construction demolition waste, consultantsand other designers need to know the current state of the art regarding both post-industrial and post-consumer recycling of roofing materials. Case studies will illus-trate what can be achieved in recycling various insulation materials and thermoplas-tic membranes during construction and at the end of service life. Obstacles to beovercome, potential solutions, and economic viability will also be addressed.

SPEAKER

Stanley P. Graveline is the vice president for technical services for Sika Sarnafil, aDivision of Sika Corp., Canton, MA. He has worked in the roofing industry for morethan 20 years in various technical, sales, and management capacities in Canada,Switzerland, and the U.S. He has participated in numerous technical committees andstandard-writing bodies in North America and Europe. Graveline is a frequent speak-er at various national and international symposia and other industry events. He is amember of the Professional Engineers Ontario and of RCI. He is currently active onvarious committees within the Cool Roof Rating Council, the Chemical Fabrics andFilm Association, the National Roofing Contractors Association, and the Center forEnvironmental Innovation in Roofing. He has a bachelor of applied science (chemicalengineering) degree from the University of Ottawa and a masters of business admin-istration from the International Institute for Management Development, Lausanne,Switzerland.

CONTACT INFO: [email protected] or 781-332-3209

Graveline - 72 Proceedings of the RCI 24th International Convention


INTRODUCTION

To state that there are asmany definitions of sustainabilityas there are people reading thispaper would only be a minor exag-geration. However, most, if not allwould probably agree that recy-cling is a key component of anyconcept of sustainability. It issomething that has been in -grained in our psyches for sometime. Who can remember a timebefore the “blue box” (or whatevercolor your city or town uses) curb-side collection of newspapers,cans, bottles, etc.? Recycling isnow a big business in the U.S.According to the National Recy -cling Coalition, there are 56,000recycling operations in the U.S.,employing 1.1 million people, witha collective annual turnover of$236 billion – a figure that appar-ently now exceeds what the trashdisposal industry takes in. Thebulk of this activity is taking placein the consumer goods industries.

Unfortunately, although therehave been a few notable successstories such as carpeting, recy-cling is far from mainstream inthe construction industry. Some

jurisdictions, such as theCity of Chica go, are begin-ning to mandate recyclingand other waste diversionapproaches. Typically,these programs are gearedto wards concrete, masonry,and other bulkier materials.The United States GreenBuilding Council (USGBC)and the Green BuildingInitiative (GBI), throughtheir LEED and GreenGlobes standards, promoterecycling and the use ofrecycled materials.

To date little has beendone in the commercial roofingsegment. The members of theChemical Fabrics and FilmAssociation (CFFA) are taking aleadership role in the develop-ment of recycling programs forthermoplastic PVC roofing mem-branes.

PreConsumer PVC MembraneRecycling

PVC has an inherent advan-tage over many other roofingmaterials with regard to recycling.As a true thermoplastic, it canreadily be heated and reprocessedwithout loss of key physical prop-erties. PVC membrane manufac-turers have, over many years,diverted many millions of poundsof production trimmings fromlandfills into a variety of innova-tive products. One company hasdeveloped a line of commercialand industrial flooring productsthat is made exclusively from itsroofing membrane productionscraps. They also produce con-crete expansion joints from thesame material. Another companyproduced walkway pads (Figure 1)

that can be welded into place onthe base roofing membrane.

Combining state-of-the-artgrinding and separation technolo-gy with the new est membraneproduction lines has enabledsome companies to take theprocess to another level. Grindingequipment is now available thatcan separate polyester scrim rein-forcement and felt backing fromthe polymer. Production linesdesigned to process the resultinggranulated vinyl material (Figure2) allow for it to be blended withvirgin feedstock into new mem-brane. With the ability to achieveloadings of preconsumer-recycledproduct of up to15% by weight innew membranes, one manufac-turer has greatly increased its vol-ume of recycled material. Where -as the production of walkwaypads consumed a few hundredthousand pounds of product ayear, now millions of pounds areconverted back into new mem-brane annually. The process hasbeen so successful that the man-ufacturer has ceased productionof the walkway pads.

Proceedings of the RCI 24th International Convention Graveline - 73

End-of-Service Life Recy cling ofThermoplastic Roof Assemblies

Figure 1 – Walkway pad madefrom 100% preconsumer-recy-cled PVC membrane.

Figure 2 – Granulate from recycledvinyl membrane.


Residual scrim fibers and feltbacking (Figure 3) from the grind-ing process are being used to rein-

force concrete landscap-ing blocks. This integrat-ed approach has resultedin achieving essentially100% conversion of rawmaterials into usableproducts.

The most obvious ex -tension of such a pro-gram would appear to bethe collection and pro-cessing of site trimmings.The various remnantsthat are typically generat-ed on any single-ply roofare ideal for recycling inthe case of PVC mem-branes. Generally cleanand un con taminated,

they can be pro cessed in the samemanner and at the same levels asproduction trimmings. The chal-

lenge lies in accumulating themand returning them to the pro-duction location. A number of re -gional trials were conducted byone manufacturer in the springand summer of 2008 (Figure 4).Although the program was enthu-siastically re ceived by many of thecontractors ap proached to partic-ipate, it achieved only modestsuccess. Translating the contrac-tor management’s support intoaction in the field is a major chal-lenge. On an average 25,000-sq-ftproject, there may be at best (atworst, considering we are dis-cussing waste material) a coupleof hundred pounds of scrap. Mostpieces are small and distributedthroughout the roof area, primar-ily around penetrations. The tech-nicians see little if any value in


Figure 3 – Polyester scrim, felt back-ing separated from the PVC membranefor recycling.

Figure 4 – Collection of site trimmings.


either hauling bags around to col-lect these scraps or in pickingthem up and bringing them to acentral collection area on the roof.Their focus is on performance,and sorting small amounts ofdebris by type is understandablynot a high priority. Various incen-tives have been considered, but todate, nothing has been found thatis commensurate with the value ofthe material being collected yet issufficient to drive behavior.

In instances where contrac-tors were able to motivate theircrews to participate, the bags oftrimmings were brought to themanufacturers’ local warehouse,where they were stored until asufficient quantity was accumu-

lated to merit shipment to theproduction location. Some con-tractors delivered the bags them-selves, and in some regions, fieldtechnicians picked up the bagsduring final inspections.

Such a program can only havea significant impact with broadparticipation by the contractorbase. Not surprisingly, in the lim-ited trial, contractors that alreadyhave a strong ecological focus andcommitment were more easilyable to get their field people on-board. Such a program cannot besuccessful in isolation. It must bepart of a much broader series ofinitiatives within a company togain any real traction.


Figure 5 – Asphalt patchingcompound produced frompostconsumer vinyl mem-branes and other recycledplastics.

Figure 6 – PVC membrane packaged for shipping to recycling plant.


Postconsumer Recycling

The “holy grail” of any wastediversion program is end-of-ser-vice life recycling. Although impo -rtant initiatives, the reclamationof plant trimmings and construc-tion site remnants represent onlya tiny fraction of the hundreds ofmillions of square feet of mem-brane produced and in stalledannually.

One company was involved ina small initiative in Massa chu -setts in the late 1990s. Vinylmembranes removed from roofs atthe end of their service life weresupplied to a local recycling com-pany that blended them withother reclaimed plastics and cre-ated a road asphalt patching com-pound (Figure 5). Although aninnovative and useful product,the volume of material that couldbe consumed was very limited.

Building on the experienceand success of their Swiss parentcompany, which started recyclingpost-consumer vinyl membranesin the early 1990s, the companybegan experimenting with theconcept in 2005.

Through trial and error andexperimentation over a three-yearperiod, the program has evolvedto the point where it is now mar-ket ready. The culmination ofthese efforts came in the summerof 2008. A 250,000-sq-ft automo-tive facility in Michigan was to bereroofed. The facility had beenrecovered once already, and bothlayers of loose-laid PVC mem-brane and insulation needed to beremoved prior to the installationof the new, mechanically attachedPVC roof assembly. The 500,000sq ft of vinyl alone would result inroughly 70 tons of debris. Allinvolved parties – the buildingowner, the contractor, and thedesigner – were highly motivatedto divert this massive amount ofmaterial from the local landfill.

After analyzing the samples ofthe competitive membranes inboth layers of the existing roof,the supplier of the new materialagreed to recycle all the mem-brane from this project. The con-tractor was responsible for remov-ing the membrane and placing itinto “gaylords” (heavy-duty 4-ft x4-ft x 4-ft cardboard boxes) sup-

plied by the membrane manufac-turer (Figure 6). They were alsoresponsible for palletizing the gay-lords and loading them for ship-ment (Figure 7). The manufactur-er of the new membrane wasresponsible for shipping the mate-rial to its third-party processingfacility, the cost of processing thematerial into the required particlesize, and shipping it to the manu-facturer’s production facility inMassachusetts.

At the completion of the pro-ject, the contractor noted thatthere was a slight learning curvefor its crews at the start of theproject. Rather than simply tear-ing everything off and dumpingthe mixed debris (membrane,insulation, ballast, etc.) intodumpsters, they had to first cutthe membrane to the specifiedwidth (up to 39 in), make rolls ofroughly 50 ft of membrane, tack-weld the flaps to prevent themfrom unrolling, and then placethem in the boxes. This didincrease their tear-off laborslightly. However, when they con-sidered the savings in dumpsterand tipping fees, they estimated


Figure 7 – Gaylords being shipped to the recycling processing facility.


that they saved at least $5,000 byrecycling the PVC membrane, netof the additional labor. This isconsistent with the results on themore than a dozen projects com-pleted to date, ranging in sizefrom 20,000 sq ft to 160,000 sq ft.Under the model described above,in all cases, the contractor at thevery least broke even versus thetraditional disposal approach,and in most cases the contractorsaved money.

This is, of course, a crucialelement for the long-term successof the program. Funda ment ally,everybody wants to do the rightthing. However, in tough econom-ic times, it can be difficult to jus-tify paying a premium for beingmore ecological. By eliminatingthe economic barrier, there is noreason not to recycle a vinyl roofmembrane at the end of its servicelife when it is technically feasibleto do so.

Similarly, the manufacturerhas found that the costs they as -sume, as described above, aretypically offset by the savings invirgin raw materials.

The concept is economicallyviable throughout the entire valuechain.

Closed-Loop LifeCycle

Once the materi-al is processed andreturned to themem brane manufac-turer, it is used toproduce new mem-brane products. Todate, the bulk of therecycled materialfrom old roofs hasbeen used in the pro-duction of a 96-milwalkway membrane(Figure 8). Morerecently, it has alsobeen used to pro-duce a protectionsheet for use in veg-etated roof systems.

Both products can accept load-ings as high as 25% of the post-consumer recycled material, with-out affecting their performance.Both competitors’ and the manu-facturer’s own materials are usedin these applications.

The manufacturer has startedto incorporate small amounts intothe back side of new membrane.Only its own aged materials areused in the production of the roof-ing and waterproofing mem-branes. With the first Europeaninstallations incorporating mem-branes with postconsumer recy-cled content approaching 15years in service, no differences inperformance have been observedcompared to membranes pro-duced exclusively with virgin rawmaterials.

All of these products will pro-vide decades of service in theirsecond life, essentially creating aclosed loop that can, in principle,perpetuate itself time and again.

Thermal Insulation

The roof membrane is, ofcourse, but one component of anyroof replacement. On any insulat-ed roof, the mass and volume ofthe thermal insulation will farexceed that of a thermoplastic

PVC membrane. Much as withPVC membranes, plant trimmingsfrom polystyrene insulations(both expanded [EPS] and extrud-ed [XPS]) can be recycled backinto new product. To date, manu-facturers have not been able tocost-effectively recycle poly-styrene back into new insulationat the end of its service life.However, with its high resistanceto water absorption, extrudedpolystyrene is an ideal candidatefor reuse if the roof membrane isto be replaced (Figure 9). Inno -vative marketing programs arebeing developed around systemsincorporating recyclable PVC roofmembranes and extruded poly-styrene covered by long-term (upto 40 years) thermal retentionwarranties, providing buildingowners with long-lasting, ex -tremely sustainable solutions totheir roofing and waterproofingneeds.

Polyisocyanurate insulation isnot recycled. Plant scraps are, insome cases, used as a fuel ininsulation plants. Like EPS, poly-isocyanurate is sometimes reusedat the end of a roof’s service life insuch applications as lining agri-cultural buildings, foundationwaterproofing, and on occasion, itis ground up and used in concreteblocks or other nonfoam applica-tions.

Learning From Others

As noted previously, the car-pet industry has had considerablesuccess with its CARE (CarpetAmerica Recovery Effort) pro-gram. The program was estab-lished in 2002. From its founding,it has experienced double-digitgrowth annually, and to date, hasdiverted over one billion pounds ofcarpet from landfills. Havingestablished that a cost-effectiveradius for collecting and process-ing materials is about 200 miles,CARE has expanded its networkof collection sites from 5 to 56over time. To some degree, it hasbecome a victim of its own suc-


Figure 8 – Walkway material incorporating25% postconsumer recycled vinyl roof mem-brane.


cess, and the industry is workingintensely to develop alternativeoutlets for the product, as collec-tions now exceed the demand forrecycling into new carpet prod-ucts.

During the PVC membranetrials, it was established that acost-effective radius for shippingold membrane from a roof loca-tion to a processing site is approx-imately 700 miles. During theearly stages of the program, a sin-gle processing company/locationwas used. As the program hasexpanded, additional sites havebeen or are in the process of beingqualified. This expands the effec-tive coverage area of the programto the eastern half of the U.S. andCanada. In 2009, efforts will bemade to develop a similar networkin the west. With the program stillin its infancy, and considering

that the market for thermoplasticPVC roof membranes continues togrow, the group does not antici-pate supply surpassing demandfor many years. However, somemember companies have alreadybegun development work on alter-native outlets for the material inorder to be ready for such aneventuality, should it arise.

Turning a Concept Into Reality

Not surprisingly, the mostsuccessful recycling projectsthroughout the trial phase werethose that were planned out inadvance and had the recyclingprocess written into the projectspecifications.

The process should start withthe condition assessment of anythermoplastic PVC roof. Once ithas been decided that the existingroof needs replacement, the

potential for recycling the mem-brane should be investigated. Atthis time, only loose-laid (ballast-ed, inverted, vegetated) and mech -anically attached membranes aresuitable for recycling. Althoughoutlets for adhered PVC mem-branes exist in Europe, they arecurrently not available in NorthAmerica. Consult with individualmembrane suppliers for their spe-cific requirements. Some mayonly recycle their own materials.Some may recycle competitors’PVC products, subject to prioranalysis and approval.

Work with the manufacturerto develop clear guidelines as toeach party’s responsibilities in theprocess. Key items to considerinclude how the material is to behandled, stored on site, and pre-pared for shipping. These ele-ments can be clearly spelled out


Figure 9 – Extruded polystyrene insulation being saved for reuse.


in the project specifications; orconversely, more general lan-guage can be used and the con-tractor instructed to provide thedetailed procedures with its biddocuments on how it will carryout the process. One example oflanguage that has been used fol-lows:

The existing roofmembrane is to be recy-cled by the manufactur-er of the replacementmembrane. The con-tractor is responsible forall costs associated withremoving the mem-brane, preparing it, andloading it for shipping,according to the manu-facturer’s publishedpro cedures.

Additionally, one may want tocall for proof of recycling experi-ence, noting a minimum number

of projects, total square footageprocessed, etc.

Prebid and job start-up meet-ings are always advisable, butthey are particularly important onrecycling projects. Although theconcepts involved and the steps tobe carried out are quite simple,most contractors will be new tothe process, and clear communi-cation, particularly with regard tothe manufacturer’s requirements,is essential for a smooth, efficientproject.

Similarly, considerationshould be given to the potentialreuse of the insulation. It shouldbe noted, however, that whereasmembrane recycling is managedthrough the manufacturer, insu-lation reuse is carried out throughrecycling companies/materialbrokers, with no involvement fromthe foam producer.

Designing for Recycling

Despite its success, an ongo-ing challenge for the CARE pro-gram is getting specifiers to de -sign for recycling. The industryneeds to do a better job of com-municating to architects and inte-rior designers the consequencesof their design decisions todaywith regard to recycling carpets atthe end of their service life.

A similar approach will needto be taken with regard to roofing.One key criterion when consider-ing the recycling of commercialroof assemblies is the ability toseparate the components (Figure10). This is equally important forinsulation reuse and for mem-brane recycling considerations. Asnoted previously, there are nomeans of recycling adhered mem-branes in North America, nor arethere outlets for the reuse ofadhered insulations. Therefore, in


Figure 10 – Removal of a mechanically attached vinyl roof to be recycled.


designing for recycling, all compo-nents should be either loose-laidor mechanically attached.

Although much work is nodoubt being done in other indus-try segments, at this time, theonly commercial roofing mem-brane that has been proven to berecyclable at the end of its servicelife is vinyl.

CONCLUSIONS

Opinions vary, and there is noclear, universal definition of whatsustainability is. There is, howev-er, a broad, general consensus onsome of the key tenets that arecentral to any definition of sus-tainability of roofing systems.These include extending roof-sys-tem lifespan, conserving energy,and minimizing the burden on theenvironment. Many systems, suchas those based on exposed ther-moplastic PVC roof membranes,have demonstrated decades-longservice lives across North Amer -ica. Between increases in the

thicknesses of thermal insulationused, acceptance and implemen-tation of cool roofing concepts,and the recognition of the benefitsof air barriers in roofing systems,tremendous progress has beenmade with regard to reducingenergy loss through roofs. Clearly,the industry has, by and large,addressed the first two tenets.The postconsumer recycling pro-grams being developed by themembers of Chemical Fabric andFilms Association will, at least inthe vinyl roofing segment, go along way in addressing the lattertenet of minimizing the burden onthe environment, thereby provid-ing all stakeholders with fullysustainable roofing and water-proofing solutions.

REFERENCES

M. Goldman, “Summary ofSixth Annual CARE Report,”May, 2008.

S.P. Graveline, “Recycling ofThermoplastic PVC Roof Mem -

branes,” Interface, April/May, 2007.

S.P. Graveline, “PVC Recy -cling,” Professional Roofing,December, 2007.

T.W. Hutchinson, “Sustain -ability and Roofing: Its TimeHas Come,” ProfessionalRoofing, March, 2004

A. Peters, “2008 Challengesand Opportunities Learnedfrom the 2007 IndependentAssessment and Brain -storm ing Sessions forCARE,” May 2008.

N.E. Russell, Recycling: ARefresher Course,w w w . r e a l s i m p l e . c o m ,September, 2008.

www.vinylroofs.org, “Avoidingthe Landfill: The Recyclingof Vinyl Roof Membranes”



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