Vinyl (PVC) windows have been around longer than youmight think. The first were manufactured in Germany in1954 as vinyl began to come to the forefront for construc-tion applications in the face of post-war wood shortagesand high prices for aluminum. This led to spectaculargrowth worldwide. According to the Vinyl Institute(www.vinylbydesign.com), of the 15 billion pounds ofvinyl produced worldwide today, about two thirds is usedin the construction industry.

Vinyl building products first found favor in the U.S.market in the early 1960s, initially in the form of pipe andthen siding. The first PVC window in the U.S., a single-glazed side-load double hung product for replacementapplication, was introduced in the U.S. in 1964 byThermal Industries. General acceptance of this newproduct was spurred by the inherent benefits of vinyl windows: low maintenance, economy and, in particular,energy efficiency — a concern that gained prominence during the “energy crisis” of the early 1970s.

Today, vinyl building products are widely acceptedand make up 58% of the market share of residential windowsales, according to 2005 research* jointly sponsored bythe American Architectural Manufacturers Association(AAMA) and the Window and Door ManufacturersAssociation (WDMA). In the U.S., over 40 million vinylwindows are sold each year. Vinyl windows and doors areexpected to claim a 53% market share (in terms of unitsales) for new residential construction applications in theU.S. by 2009. In residential remodeling, vinyl productsare projected to command more than 65% of the market.

In addition, the use of vinyl is expanding beyond windows and doors to include skylights, decking and fencing products. Vinyl siding has also recently becomethe dominant residential cladding, overtaking wood, brickand aluminum.

Why this degree of acceptance? Primarily because vinylhas proven itself to be a well-performing, cost effectivebuilding material.

But vinyl had to overcome some misconceptions andcompetitive “spins” to attain this level of acceptance.Contractors and consumers initially regarded vinyl buildingproducts with skepticism when they first appeared on theU.S. market. After all, structures should be built withsolid, robust “traditional” materials, shouldn’t they? Howcan “plastic”—perceived early on as the same “cheap” stuffused to make kids’ toys—be acceptable for construction?

Perhaps this initial concern was understandable, giventhe limited use of rudimentary plastics half a century ago.But, things have changed, thanks to advances in materialsengineering. Once the technology was better understood,the material-oriented competitive claims began to blur.While some of the old misconceptions may still ring true tosome people, today’s vinyl, highly engineered specificallyfor construction applications, is as different from early“toy” plastic as stainless steel is from cast iron.

So, What is Vinyl Anyway?Vinyl, more technically known as Poly Vinyl Chloride, orPVC, was first synthesized in 1872, but wasn’t investigatedseriously for practical applications until 1926 at B.F.Goodrich by Dr. Waldo Lonsbury Semon. Among its firstpractical uses was jacketing for electrical wiring on navalships during World War II, where it replaced increasingly

A A M A A I A / C E S D I S T A N C E E D U C A T I O N

Vinyl Windows: Designed for PerformanceThis program is registered with the AIA/CES for continuing professional education. As such, it doesnot include content that may be deemed or construed to be an approval or endorsement by the AIA ofany material of construction or any method or manner of handling, using, distributing, or dealing inany material or product. Questions related to specific materials, methods, and services will beaddressed at your request.

* 2006 AAMA/WDMA U.S. Industry Market Studies

1

scarce rubber insulation and flammable cloth jacketing.Shortly after the war, material shortages led to experimen-tation with vinyl window frames, flooring and wallpapercoating. The advent of PVC pipe proved critical to maintaining clean water delivery all around the globe.

Salt, which is abundant in supply, is actually the pri-mary ingredient of vinyl. Chlorine derived from the elec-trolysis of salt water is combined with ethylene (a petro-leum derivative) in a clean, automated closed-loop processthat yields ethylene dichloride (EDC). EDC is then“cracked” under heat to produce vinyl chlorine monomer(VCM). Vinyl resin, typically in powder or granular form,is produced when the VCM is subjected to polymerizationto produce polyvinyl chloride, or PVC. Polymerization isthe process by which smaller organic molecules(monomers) are bonded together chemically into a muchlarger, chainlike repeating molecule called a polymer. Thepolymer is typically engineered to have very differentphysical properties than the constituent monomer(s). Theprimary constituents of PVC, for example, ethylene andchlorine, have very different properties than the final PVCpolymer.

The resulting PVC resin can be mixed with a variety ofadditives and modifiers to improve the impact resistance,thermal stability, UV resistance and weathering character-istics. Such high-tech compounding and unique processingtechniques are the keys to vinyl’s versatility.

Physical property specifications for PVC compoundsused for windows can be found in American Society forTesting and Materials (ASTM) standard ASTM D4216Specification for Rigid PVC and Related Plastic BuildingProduct Compounds. It provides minimum values and rangesfor tensile, flexural, and impact strength, coefficient ofexpansion, and heat deflection temperature.

For use as window profiles, the specially-formulatedresin, augmented with processing additives and pigments,must be processed into final form through an extrusionprocess. In this step, the resin is melted and the resultingsoft mass is forced through dies that give it its final shape.The extrusions are cooled under carefully controlled conditions to ensure that intended shapes and tolerancesare maintained.

ASTM D4726 Specification for Rigid PVC ExteriorProfiles Used for Assembled Windows and Doors concentrateson the extrusion process quality. It outlines the testingprotocol for dimensional stability, weathering, color holdand impact strength before and after weathering, andweight tolerance.

These extrusions, which form the basis for a vinylwindow assembly, are shipped to a window fabricator inbulk lengths. The window fabricator, using manual orautomated equipment, then cuts the bulk lengths to thespecified dimensions of the window. The profiles are thentooled or machined to accept the appropriate hardwareand components for assembly. The mitered corners offrame and sash members are most often fusion-weldedtogether, but in some instances mechanical fasteners orcorner keys can also be used to complete the corner connection. Automated corner-cleaners precisely removethe weld sprue (waste material) to ensure a smoothappearance. The remainder of the assembly entails installation of hardware components (locks, keepers, balances, operators), weatherstripping and in most casesan insulating glass unit is preferred because it providesbetter thermal performance. The completed window iscleaned and inspected, then labeled appropriately beforepackaging, making it ready for shipment to the customer.

2

3

Why Specify Vinyl Windows?An Amazing Success Story

Used in hundreds of industries, vinyl is now the secondlargest volume plastic produced worldwide and thelargest volume plastic for building and construction products. Vinyl products have revolutionized the buildingindustry because, as a building material, vinyl offersremarkable versatility. It can be flexible, rigid, customizedfor application and produced in nearly any color, patternand texture. Vinyl combines many characteristics of traditional materials with advanced technologies.

A look at the fenestration segment of the vast buildingproducts market reveals the amazing speed at whichvinyl-framed windows and glass doors have penetratedresidential and light commercial applications, with annualgrowth rates in the neighborhood of 20%.

20

18

16

14

12

10

8

6

4

2

02001 2002 2003 2004 2005 2006F 2007F 2008F 2009F

Growth of Vinyl Windows (United States)New Construction (millions of units)

AluminumWoodVinylFiberglassOther

45

40

35

30

25

20

15

10

5

02001

Source: 2005 AAMA/WDMA U.S. Industry Statistical Review and Forecast

2002 2003 2004 2005 2006F 2007F 2008F 2009F

Total Construction (millions of units)

30

25

20

15

10

5

02001 2002 2003 2004 2005 2006F 2007F 2008F 2009F

Remodeling & Replacement (millions of units)

AluminumWoodVinylFiberglassOther

Please note that the categories of "Fiberglass" and "Other" had very similar numbers, which may be difficult to decipher in the graph above.

AluminumWoodVinylFiberglassOther

AluminumWoodVinylFiberglassOther

Other1%Fiberglass

2%

Vinyl60%

Wood25%

Aluminum12%

2009 Projected United States Market Share2009 Projected Residential Windows

While vinyl windows were first aimed at the replace-ment and remodeling market, passing aluminum in preference for that application in 1988 and wood by 1996,they first became visible on the radar screen for newconstruction only as recently as 1987. Driven by theiradvantages of low cost and ease of maintenance, vinylproducts entered a strong growth period in the 1990s, in1999 capturing the leadership position in the overall marketshare race, and tallying 58% by 2005. By 2009, they areprojected to be the leader in residential applications,accounting for 60% of all windows sold, according to theAAMA/WDMA 2006 U.S. Industry Statistical Review andForecast.

Vinyl windows are used on all types of housing (high-end custom, high-volume tract, manufactured housingand multi-unit housing), so they are projected to continuegaining market share before maturing in about 20 years.

The Proof Is In the PerformanceThe simple reason for this revolution is cost-effective performance, which is the primary reason for specifyingvinyl windows for residential and light commercial projects. In addition to well-promoted consumer benefitsof economy and ease of maintenance, that performance is well documented in several key areas of particularinterest to architects and specifiers, which are listedbelow and described in further detail later in this article:

n Low Maintenance n Heat Build-Up Characteristicsn Energy Efficiency n Long-Term Durabilityn Structural Strength n Green Buildingn Weatherability n Lead Contentn Chemical Resistance n Dioxin Releasesn Fire Resistance n Solid Waste and Recyclabilityn Impact Resistance n Design Flexibilityn Dimensional Stability n Exterior Colors andn Thermal Expansion Interior Finishes

Low MaintenancePerhaps the original benefit of vinyl windows that washeavily promoted to the homeowner, low maintenancehas been a prime factor in the exploding market share thatvinyl products have enjoyed – including floors and wallcoverings as well as windows and doors. With vinyl windows, color can be integral to vinyl frames throughthe addition of pigments to the vinyl formulation, not asurface coating, so there is never a need for touch-up dueto scratches. Extremely durable, vinyl products resist rotting, chipping, peeling and corrosion, are not susceptibleto insect or fungus attack, and can be easily cleaned witha solution of mild soap and warm water. In fact, vinyl’sability to be cleaned easily and thoroughly makes it a popular material for use in hospitals and other health careenvironments.

The economic, durability and low maintenance attrib-utes of vinyl windows and doors led Habitat for HumanityInternational to choose them for its volunteer-built homesfor families in need. Due to ease of installation, vinyl windows are ideally suited to the varying skill levels of thethousands of workers involved in Habitat builds each year.Vinyl building products are a cornerstone of affordablehousing.

Energy EfficiencyVinyl’s popularity in the U.S. is largely due to energy effi-ciency. Because it is such an effective thermal insulator(having a low U-factor, also known as U-value), vinyl iswell recognized as an excellent frame material for energy-efficient windows. Currently, 43% of the windows listedin the National Fenestration Rating Council (NFRC)

4

Certified Products Directory are framed with vinyl. Many utilities are offering incentives to builders whoinstall energy-efficient windows in homes. Federal and statetax incentives also offer rebates or special deductions forthe use of these products. Vinyl windows are commonlyused to meet these requirements. The Department ofEnergy’s (DOE) Energy Star® program sets forth climate-dependent criteria for window performance which areeasily met by vinyl products.

All energy-saving glazing options are of course availablein vinyl windows: double or triple pane insulating glazing,with air or gas (argon or krypton) infills, or low emissivity(“low-E”) coatings. The latter are composed of an extremelythin layer of metal applied to glass to maximize beneficialsolar heat gain and reflect heat back into the house. Whenapplied to the outer pane (typically for use in hot climates),low-E coating minimizes heat gain and reflects heat backoutdoors.

The chart compares vinyl’s legendary energy efficientcharacteristics.

For example, the typical U-factor of vinyl windowframes ranges from 0.3 to 0.5, with lower numbers meaning less heat flow and better thermal performance.

The ultimate goal – expressed in the U.S. Departmentof Energy’s “2020 R&D Roadmap” – is to develop windowsthat have zero annual energy cost. The industry alreadyenvisions “super windows” that will use spectrally selectiveand automated electrochromatic glazing to admit solarheat gain in winter to supplant heat loss and reflect heatback outside in summer. The multi-chambered vinyl productframes are designed to trap air, known to provide optimalinsulating characteristics against heat transfer year-round.

In addition to saving on home heating and coolingbills, the manufacture of vinyl products takes relativelylittle energy. Production of all vinyl products worldwideaccounts for less than 0.3% of all oil and gas consumption,with windows and doors accounting for a small fraction ofthat. Vinyl Institute figures show that the use of vinyl as aconstruction material actually saves more than 40 millionbarrels of oil per year compared to other building and construction alternatives. Vinyl products in general have

THERMAL PERFORMANCE

U-Factor* Range for Vinyl Framing MaterialFrame Material U-FactorVinyl 0.3 – 0.5Insulating vinyl 0.2 – 0.4

Source: Residential Windows: A Guide to New Technologies and EnergyPerformance, Third Edition

* A measure of the rate of non-solar heat loss or gain through a material orassembly. The lower the U-factor, the greater a window's resistance to heatflow and the better its insulating value. U-factor is equivalent to 1/R-value.

low embodied energy, which is the amount of energy usedto convert raw material into a final product. A lifecyclestudy by Franklin Associates has shown that the use ofvinyl over alternatives in window frames saves the UnitedStates nearly two trillion BTUs of energy per year, enoughto meet the yearly electrical needs of 20,000 single-familyhomes.

Structural StrengthVinyl serves admirably within the massive residential andlight commercial markets. This is because most vinyl window profiles are engineered with a multi-chambereddesign that can actually be stronger than a solid frame.The network of baffles and chambers, like those of a honeycomb structure, creates a favorable weight-to-strength ratio. For larger windows, the strength of vinylframes is often bolstered by inserting metal reinforcingmembers into the chambers.Corners of the frames arefused together using anadvanced heat weldingprocess, providing even morestrength and ensuring thatthe windows are air- andwater-resistant. Automatedequipment ensures precisionand quality throughout themanufacturing process.

As we will discuss shortly,using performance-basedstandards as the basis forspecifying levels the playingfield and removes any concern about structural perform-ance of any framing material for given job-site conditions.

WeatherabilityWeatherability is the ability to retain impact strength,color, and other physical properties (e.g., gloss, texture, etc.)over a period of time despite exposure to the elements,such as ultraviolet (UV) rays in the solar spectrum,extreme temperatures, wind, rain, snow and ice.Weathering studies at test sites in various climates andcommercial applications around the globe prove thatappropriate additives such as Titanium Dioxide (TiO2) andspecially-formulated pigments can effectively make vinylproducts very resist to weathering while requiring low orno maintenance during the service life of the products.

TiO2 is well recognized for its ability to enhance the weatherability of vinyl products—so much so thatmost vinyl siding, windows and doors contain anywherefrom 5% to 10% TiO2 by weight. Because of its chemical

properties, TiO2 reflects about 95% of the visible light,making it an effective bright white pigment. It also absorbsmuch of the incident solar UV light, which protects thepolymer matrix from photochemical degradation, the causeof discoloration and loss of impact strength over time.There are two types of crystal structure of TiO2: Rutileand Anatase. Because of the higher UV light absorbingproperty of the rutile-type of TiO2, it is the preferred TiO2for achieving weather resistance in vinyl products.

Commercially available TiO2 is typically surface-treated, and depending on the surface treatment, is categorized as a “chalking” (i.e. “non-durable”) or a “non-chalking” (i.e. “durable”) TiO2. Both chalking andnon-chalking TiO2 provide the same level of weatherabilityto vinyl products in terms of impact retention, whilechalking grade promotes chalking on the surface of theproduct when exposed to UV light and moisture. Surface

chalking is preferred whengloss retention is not requiredand a long-lasting white colorsurface is desirable. On theother hand, a non-chalkingTiO2 should be used whengloss retention is requiredand/or when the vinyl productis tinted (non-white).

Chemical ResistanceVinyl window profiles are formulated to resist theeffects of moisture, householdchemicals and cleaning

agents, pesticides and corrosive conditions (such as nearthe sea coast or heavy industrial areas). This is one reasonthat PVC has found popular use as water piping.

Fire ResistanceThe fire hazard of a product is defined by several factors,including its ignitability or flammability, the amount ofheat released when it burns, the rate at which this heat isreleased, the flame spread, smoke production, and the toxicity of the smoke.

Being a plastic, PVC might be suspected of hazardousbehavior in some of these categories. However, it in truthhas excellent fire properties due to its chlorine content. Inparticular, PVC not only has a high flash ignition point(736°F [391°C] per ASTM D 1929 test methods), it is actually self-extinguishing once the source of heat orflame is removed (i.e., it will not support combustion),according to the Vinyl Institute’s brochure entitled “Fireand Polyvinyl Chloride.”

5

Generally, a distinction must be made between plasticized vinyl—used to make flexible products such aswire coatings, upholstery or wall coverings—which hasless favorable fire properties than the unplasticized (rigid)PVC used in pipe, siding or window profiles. The latterproducts, in fact, have higher ignition temperatures, lowerflame spread and lower heat release rates in a fire thansimilar samples of wood, according to the Vinyl Institute.

n Flame spread indicates the tendency of a material tospread flame. With a flame spread index of 10 as deter-mined per the ASTM E 162 radiant panel test (com-pared, for example, to plywood at 143), PVC will notspread flame on its own.

n Heat release indicates the ability of a burning object tospread fire to nearby objects by giving off enough heatto ignite them. In addition, this heat has to be releasedfast enough not to be dissipated while travelingthrough the air to theobject. In terms of overallfire hazard, the rate of heatrelease (RHR) has in factbeen shown to be muchmore important than easeof ignition, flame spreador smoke toxicity. This isreflected in the fact thatfire fatalities most oftenoccur when the rate ofheat release is sufficientlylarge to cause most of theitems in a room to burn. When measured in a varietyof ways in the lab, very few materials have lower ratesof heat release than PVC. In full scale room tests (e.g.,ASTM E 1537, E 1590, etc.), considered most represen-tative of actual fires, rigid PVC released 38 kW of heatenergy over the 13 minute test period, while oak woodreleased 109 kW.

Dense smoke obscures light and hinders escape froma fire, and can be quite toxic. This is why smoke inhalationis by far the greatest cause of fire injury or fatality. Smokeproduction figures from tests of PVC show it to be amongthe lowest smoke producers of all polymers. In full scaleroom tests, measurements taken at the door to the testroom showed that peak smoke generation from rigid PVCwas only 24% that of oak wood. In terms of smoke toxicity,the smoke from virtually all organic materials falls withina very narrow range. Within that range, the toxicity ofPVC smoke ranks between that of wood and ABS plastic.

Vinyl also produces less carbon monoxide than mostorganic materials. By comparison, nicotine is consideredto be about 70 times as toxic as smoke from burning PVC.

However, relative performance in isolated structurefires is not the whole issue when it comes to fire resistance. Windows are considered to be one of the mostvulnerable portions of structures located in the “Wildland-Urban Interface” (WUI)—boundary areas where suburbanresidential developments meet fire prone open grasslands,forests or brushy areas. Regulatory action, mostly at locallevels in California, Arizona and Colorado—well-publicizedsites for wildfires, initially sought to essentially ban vinylwindows under the assumption that the PVC framingmembers would soften and sag when exposed to exteriorfires, allowing the glass to fall out, exposing the buildingto the entry of flames.

As a result of discussions between the window industryand fire officials, FEMA-sponsored fire performancetests of exterior building components conducted by theUniversity of California ForestProducts Laboratory (UCFPL),showed that the glass was theweakest link in windows, failing first in each and everytest, with tempered double-pane glass outlasting single-pane significantly. Also, noneof the framing materials sustained combustion. Evenwhere frames did fail, there

was no discernable difference among vinyl or clad wood.Researchers also pointed out that, with regard to the possible softening and sagging of vinyl frames under exposure to radiant heating, steel- or aluminum-reinforcedmembers were likely to protect against such failures. Fireprotection officials additionally recommended that, formaximum protection against WUI fires, vinyl windowframe and sash profiles should be certified under theAAMA Profile Certification Program, while complete window units should be certified and labeled as conformingto current window performance standards.

Impact ResistanceImpact resistance is a very important property for PVCextrusions. Consider that, before assembly, a PVC profileis punched, routed, and sawed. During assembly it iswelded, the corners cleaned and hardware installed.Shipment entails bouncing around in a trailer truck, movingseveral times in a warehouse or retail outlet with an

6

unforgiving forklift truck and finally riding in the back ofa pickup to the job site. Additives such as impact modifiers(i.e., acrylic and CPE), enhance the ability of PVC to resistimpact, and—as we will see shortly—testing for impactresistance is a requirement for certification of vinyl profilesfor use in AAMA-certified windows.

One area that standard test methods have addressedmore zealously – spurred by recent brutal hurricane seasonsof 2004 and 2005 along the southeastern United Statescoastal regions, Atlantic and Gulf coasts specifically – isthat of impact resistance of the entire window assembly.

Led by the understandably stringent requirements ofFlorida’s Miami-Dade County (as expressed in theirTAS201 and 203 standards), products are rigorously testedfor resistance to the impact of flying debris. This has beenshown to be the leading cause of window failure duringsevere storms, not wind pressure alone.

These tests are not trivial.An air cannon shoots a two-by-four stud weighing 9.25pounds directly at a windowat a speed of 50 feet per second (37 mph). Each testspecimen is impacted twice,and all mulled assembliesmust be impacted additional-ly on the mullion, where theseparate units are joined.Then, the window is subjectedto 9,000 cycles of combinedpositive and negative pres-sure. Dade County-approvedproducts must withstand 146 mph wind speed (equivalentto a strong Category 4 hurricane). However, each countyor city has its own wind speed requirement, based onproximity to coastline. To achieve Dade County approval,each window must continue to be operable after runningthis gauntlet of tests. Other coastal jurisdictions requiretesting to ASTM E 1886, Standard Test Method forPerformance of Exterior Windows, Curtain Walls, Doors andImpact Protective Systems Impacted by Missile(s) and Exposedto Cyclic Pressure Differentials and ASTM E 1996, StandardSpecification for Performance of Exterior Windows, CurtainWalls, Doors and Impact Protective Systems Impacted byWindborne Debris in Hurricanes, which form the basis ofAAMA 506, Voluntary Specifications for Hurricane Impactand Cycle Testing of Fenestration Products.

Vinyl impact-resistant windows, typically with steel-reinforced frames and laminated glass, regularly passthese tests.

Dimensional StabilityDimensional stability – the ability to retain size and shapeover a product’s service life – is one of the most importantrequirements for building products. Problems such aswarping, bowing and other changes may occur when theyare excessively heated by the sun.

Polymeric materials, such as vinyl and ABS, expandand contract (have a higher coefficient of thermal expansion)to a greater degree than other building materials. Heatbuildup, or infrared energy absorption upon exposure tothe sun, will determine the thermal stability of a coloredvinyl.

Thermal ExpansionUnder identical conditions of elevated heat exposure,vinyl and other polymeric materials such as ABS expandmore than four times as much as glass due to their greater

thermal expansion. Vinylexpands at a rate anywherefrom 4.4 to 8.8 times that ofglass, although heat-stabilizedcompounds perform at thelower end of this range.

Of course, real-world conditions (such as the factthat only small portions of theexterior surface of a windowframe are subjected to extremesolar heating at any giventime and are restrained fromexcessive expansion by thewall opening) and proper

window profile design (such as providing adequate glassbite) accommodate these differences in propertiesbetween basic raw materials.

Heat Build-Up CharacteristicsBecause dark-colored surfaces absorb heat more readily thanlight-colored surfaces, heat build-up in framing materialdue to solar radiation is very color-dependent and is controlled by the pigment system used. The same colorwith different pigment systems can have widely varyingheat build-up numbers. The ASTM D 4803 Standard TestMethod for Predicting Heat Build-up in PVC BuildingProducts measures the increase in heat within a product.Different areas of the United States receive differentamounts of solar radiation and have different high ambienttemperatures. These two climate characteristics along withheat build-up can be used to evaluate various environmentsthroughout the country.

7

Long-Term Durability and Green BuildingBuilders are finding that in addition to the environmentalallure of “sustainable” (renewable or recyclable) or“green” buildings (those with low life-cycle environmentalimpact), they are also more economical over the long runbecause of better energy efficiency. However, they arealso realizing that “green” is long-lasting and appealing tooccupants due to abundant windows and skylightings thatbring in fresh air and natural light, fostering fewer “sickdays” and greater productivity. An environmentally sensibleapproach to building considers the building’s impact from“cradle to grave” – from design, siting and construction tooperation of the building through its lifetime to final disposition of the building and its materials at the end oftheir useful life.

Despite some activists’ claims to the contrary, vinylbuilding products are increasingly included on lists of“green” building products.For example, a study by lifecycle assessment expertsGreg Norris and Peter Yost ofMIT and Yale Universitiesshows the use phase is themost important in terms of amaterial’s life cycle impact,and counterbalances over timethe environmental impactstemming from a product’smanufacture. Vinyl, becauseof energy efficiency, thermal-insulating value, low contri-bution to greenhouse gases,easy maintenance and excellent durability of productsmade from it, provides extensive life cycle benefits.

Because vinyl windows and doors will be in servicefor many years with minimal maintenance, whichrequires no periodic use of stripping chemicals, paints orstains, and no associated clean-up and disposal, use ofvinyl tends to reduce air and groundwater pollution.

Vinyl’s ease of recyclability also lends itself to use asa green material.

RecyclabilityDue to the thermoplastic nature of vinyl, products andmaterials can be processed and reprocessed using heatwithout loss of properties.

According to a 1999 study by Principia Partners, morethan one billion pounds of vinyl were recovered and recycled into useful products in North America in 1997.About 18 million pounds of that was post-consumer vinyldiverted from landfills and recycled into second-generation

products. Overall, more than 99% of all manufacturedvinyl compound ends up in a finished product, due towidespread post-industrial recycling.

A 2002 Principia Report found that of the 3.2 billionpounds of vinyl compound consumed in the manufactureof new siding and windows, only 201 million pounds ofscrap is generated, such as when window manufacturerscut mitered corners from extrusions. The majority of thisis reclaimed for use in the same or similar applications,such as pipe, conduit, siding, fencing and garden lumber.For example, some manufacturers have produced vinylwindow frames containing up to 25% recycle content. Intotal, less than 20 million pounds of scrap is discardedresulting in a 99% efficient process.

Due to vinyl’s durability, the vast majority of vinylwindows installed over the past 25 years are still in useand, therefore, are not candidates for end-of-life or post-

consumer recycling. Theirestimated service life of morethan 50 years means fewolder ones are being replaced(although there is a growingtrend for older vinyl windowsto be replaced with newer,more efficient vinyl units).

When the time for finaldisposal comes, however, vinylwindows–like all vinyl–can berecycled. The low contributionto the solid waste stream isprimarily a result of vinyl’suse in long-lived applications,

such as windows. The vinyl that is discarded is so stablethat it degrades very slowly in a landfill and is thus not asource of groundwater pollution.

As with any building product, the key to greater post-consumer vinyl window recycling is to find more cost-effective ways to collect, separate, process and transportused materials to a manufacturer for use in new products.

Lead ContentLinking vinyl windows and doors to lead-laced PVC products is erroneous. The simple truth is that no lead isadded to the vast majority of vinyl sash and frames usedin windows and glass doors. All of the 12,601 vinyl profilescertified in the AAMA Profile Certification Program musthave no lead added during processing and must containless than 0.02% by weight of lead, a level that meetsCalifornia’s stringent requirements (more rigorous than theConsumer Product Safety Commission level of 0.06%). Allcoatings and laminates must also meet this requirement ifapplied on AAMA-certified PVC window profiles.

8

Dioxin ReleasesDioxin is a persistent and toxic substance that is producedwhen chlorine-containing compounds are burned in thepresence of hydrocarbons. In addition to being a knowncarcinogen, dioxin exposure has been linked to reproductiveand hormonal disorders, diabetes, learning disabilities,immune system suppression, lung problems and skin ailments.

Because chlorine can be found almost everywhere onearth (e.g., in salt), dioxin will be formed when most thingsburn. Because chlorine is so pervasive in the environment,dioxin is a byproduct of natural events like forest fires,lightning and volcanoes, as well as manmade activitiessuch as burning wood and backyard trash, diesel vehicleemissions and various manufacturing processes includingvinyl production.

The good news is that dioxin emissions and levels inthe environment are declining, according to data from theU.S. Environmental Protection Agency (EPA). Dioxinemissions from human sources in particular have declinedby more than 90% in recent decades, and further declinescontinue to be documented. This has occurred even asproduction of vinyl has soared, proving that vinyl produc-tion and disposal are not significant contributors to dioxinlevels, accounting for less than 1% of total dioxin releasesto the environment. This simple fact indicates that there isno significant relationship between vinyl use and aggregatedioxin releases to the environment. Interestingly, EPAstatistics also show that the biggest manmade sources ofdioxin today by far are backyard trash burning and residential wood burning (i.e., fireplaces).

With respect to the incineration of vinyl, scientificstudies indicate that the most important variable affectingdioxin emissions from incinerators is the design and operation of the incinerator unit, not the feedstock. Whenburning is well controlled, as it is in modern incinerators,very little dioxin is made or emitted. However, in uncontrolled burning (e.g., volcanoes, forest fires, oldincinerators, backyard burn barrels and accidental building fires), dioxin can be formed in larger amounts.

Design FlexibilityOf definite appeal to architects and designers, vinyl windows permit wide latitude of creative expression.Because vinyl is a thermoplastic material, it can be bentwhen sufficiently heated to create innovative shapes suchas half and full rounds. Custom colors and textures —gloss, matte or wood-grain — offer a wide variety of com-binations. Ease of fabrication affords special sizes andconfigurations without high cost.

Exterior Colors and Interior FinishesAs noted earlier, basic colors can be integrated homoge-neously into the frame material by adding pigments to thevinyl formulation. However, the range and depth of colorsthat can be practically integrated in this manner is limited– traditionally to the familiar choices of white, gray, beige,dark brown, and light brown. To offer a virtually unlimitedvariety of interior and exterior colors and finishes, layersof color may also be added to selected surfaces by thecoextrusion process, in which a capstock (thin layer of surface color) is bonded to the substrate. Color optionscan also be obtained through embossed laminates in solidor wood-grain patterns and finishes. Factory-applied organiccoatings further expand on color choices available.

Adherence to AAMA standards for these coextruded,laminated or coated finishes ensures that they will perform well in terms of film integrity, exterior weather-ability and general appearance over many years of service.

The Range of Vinyl Window and Door ProductsVinyl windows, doors and skylights are readily availablein all traditional product types (hung, sliding, casement,picture, awning, bay, bow, patio door, etc.).

The most popular configurations in use today aremulled-together window assemblies featuring combinationsof fixed and operable units plus non-rectangular shapessuch as full rounds, half rounds, hexagons, trapezoids,quarter rounds, ellipticals, triangles, etc. Art glass typesfeature beveled, V-grooved and stained glass. In addition,composite products utilize laminated foils, veneers and stainable wood fiber composites to provide the look ofwood on the inside, combined with the maintenance-freevinyl on the exterior.

9

Exterior Colors / Interior Finishes

Extruded Color

Co-Extruded Color

Any given window product, regardless of material,can be well designed and competently made, or it can bepoorly designed and defectively made. The distinctionbetween “high end” and “low end” products is based noton its framing material, but on the performance level thatthe products are designed to meet – something that goesbeyond clever advertising or competitive claims. The issueis performance quality, not material.

Performance-based standards, a concept pioneered forwindows and doors by AAMA, rate completely fabricatedwindows, doors and skylights according to their structuralperformance under wind loading and their level of resistanceto air leakage and water penetration. In addition, forcedentry resistance is also required. These standards providea uniform basis for comparing these key performanceattributes of different manufacturers’ products of thesame type and grade, thereby taking into account the

unique properties and com-parative strengths and weak-nesses of all profile materials.

The product designerdetermines the level of per-formance desired under spec-ified conditions, such as windloading. Then, factoring thewell-understood characteris-tics of the material and com-ponents into the equation, thedesigner builds a window thatmeets the specified perform-ance level. In general, therequired performance drives

the design.It is the buyer’s task to first determine the tradeoff

between performance levels and cost that is acceptable forthe job at hand. Given equal performance requirements,the choice of material basically reduces to one of prefer-ence with regard to operating features, appearance, brandname or manufacturer’s reputation and other factors forthe specific application, rather than determining which is“better” than another at some absolute level.

The task is more straightforward with the materialneutral, performance-based standards that the industry hasdeveloped over the last decade: AAMA/NWWDA 101/I.S.2-97, ANSI/AAMA/WDMA 101/I.S. 2/NAFS-02 and thenewest, AAMA/WDMA/CSA 101/I.S. 2/A440-05.

The latter is the first fenestration standard jointly published by U.S. (AAMA/WDMA) and Canadian (CSA)Associations. This standard, or an updated version of it,will eventually replace the pre-existing standards. Like theothers, it identifies the requirements for windows, glass

Cellular PVCRelative newcomers to the marketplace, windows made ofcellular PVC are being well received as an alternative tothose made of either rigid vinyl or wood.

Cellular PVC is created by a foaming extrusionprocess, known as “celuka,” that creates tiny air bubbleswithin the shape, resulting in a density less than half thatof regular PVC. When the extruded material is cooled, itforms a smooth, hard skin that doesn’t absorb stains orbleed. Cellular PVC is not quite as strong as solid PVC,having a tensile strength of 2,000 to 5,000 psi where solidvinyl has a tensile strength of about 6,400 psi. Cellular PVCresists heat deflection up to 150°F and has a coefficient ofthermal expansion similar to that of rigid PVC. It weighsabout the same as soft wood, and has superior U-values.Cellular PVC formulations include UV protectors andimpact modifiers as with solid PVC, and extrusions can be welded like solid vinyl tofabricate window assemblies.

Its benefit is that while itcan be economically extrudedinto intricate profile shapeslike solid vinyl, it can be cut,milled and fastened likewood, yet avoids undesirableproblems, such as rot, split,water absorption, peelingpaint and termites. It can be surface-textured and/or laminated with a surface filmto accurately simulate thelook of real wood grain andpainted to match any color specification. This makes it agood alternative for historical renovation projects.

In addition to windows, cellular PVC is used as lumber,interior and exterior trim, paneling, blinds and furniture.It does become brittle below 40°F, which is more of aninstallation issue (pre-drilling recommended during coldweather) than an in-service concern.

Rely on Industry Standards andCertification for SpecificationsMaterial pros and cons aside, all window profile materialsoffer special advantages for dealing with the performancechallenges posed by climate, building design or consumerpreference for various applications. Material evaluationsare rendered virtually immaterial when one stops compar-ing the basic characteristics of flat pieces of unsupportedmaterial and instead concentrates on the performance ofthe completely fabricated window unit.

10

doors and skylights for R, LC, C, HC and AW Performance Classes, but for the first time adds side-hinged exterior doors.

These standards provide a uniform basis by which allmaterials and products can be tested and compared on alevel playing field. All are currently referenced by theInternational Building Code (IBC) and InternationalResidential Code (IRC) as criteria for compliance of windowsand sliding glass doors, regardless of framing material.

These standards and AAMA product certification gobeyond basic quality assurance for completed windowunits by recognizing that a window is a complex system of components—extrusions, as well as finishes, glass,screening, weatherstrip, sealants and hardware—thatmust perform properly and continuously over a long servicelife. Therefore, any effective definition of window qualitymust encompass the performance of these components as well as the way they inter-act to make a completed window unit.

PVC ProfileCertificationProducers of PVC profileswho wish to sell to manufac-turers of vinyl windows thatare certified under the AAMACertification Programs mustcertify their extrusions underthe AAMA Profile Certifica-tion Program.

Under the Profile Certifi-cation Program, samples of vinyl extrusions are tested byan accredited third-party laboratory for conformance withAAMA 303, Voluntary Specification for Poly (Vinyl Chloride)(PVC) Exterior Profile Extrusions or AAMA 308, VoluntarySpecification for Cellular Poly Vinyl Chloride (PVC) ExteriorProfiles for cellular PVC.

Vinyl windows must be made from extrusions whichcomply with AAMA 303 in order to be eligible for authorization for certification under the AAMACertification Program. The requirements for completedextrusions include extensive physical testing by an independent laboratory to verify impact resistance,dimensional stability, heat resistance, weight toleranceand color fastness.

Impact resistance of the PVC profile is verified with adropped-dart test for resistance to cracking or breaking.

The profile is also subjected to temperature extremesto verify dimensional stability. A 180°F water bath testensures that the extrusion processing did not induce resid-

ual stresses that would result in excessive part shrinkageduring exposure to elevated temperatures. The part is alsoexposed to a 300°F hot air oven to uncover any surfaceimperfections such as chipping, blistering and cracks.

Adherence to established color-hold guidelines areassured through actual exposures for two years at threesites—South Florida, Arizona and Ohio. These three sitesrepresent the typical U.S. climatic extremes of temperature cycling, humidity, and acid rain.

Surface treatments are tested extensively and are alsoexposed outdoors to ensure long term bond integrity andcolor retention. Lamination tests include a pull-off test following immersion in boiling water to determine adhesion.

Other testing requirements for laminates includeresistance to abrasion, mortar, muriatic acid, detergents andsealant compatibility. Coatings are also tested to evaluate

adhesion, stain resistance,chemical resistance, coloruniformity, gloss, hardness,detergent resistance andweatherability. In-plant qualitycontrol sampling frequency,test requirements and recordkeeping are spelled out forboth coated and laminatedwindow profiles.

Once all tests are passed,the extruder must also preparea Quality Control Manual setting forth the proceduresused to assure ongoing

conformance of the product with the AAMA 303 specifi-cation. At least two unannounced in-plant inspections areconducted annually by third-party inspectors to determinecontinued compliance with the program and includes therandom selection of production line samples for testing.AAMA 308 sets forth performance requirements for cellularPVC extrusions, which include dimensional stability,weatherability, heat resistance, hardness and weight tolerance. Cellular PVC profiles must meet AAMA 308requirements to be approved under the ProfileCertification Program and eligible for use in products thatare certified under the AAMA Window & DoorCertification Program.

Laminates and CoatingsAs noted earlier, laminates and factory-applied organiccoatings expand on the color choices available as comparedto integral colors achieved through the addition of pigmentsto the vinyl material. AAMA standards for these laminates

11

12

and coatings on vinyl profiles define tests (per ASTMmethods) and performance requirements that they mustmeet if the profiles are to be approved for use in AAMA-certified windows and doors.

AAMA 307, Voluntary Performance Requirements andTest Procedures for Laminates Intended for Use on AAMACertified Plastic Profiles, establishes performance require-ments for decorative laminate materials intended forapplication to either the interior or exterior surfaces of theprofiles.

AAMA 613, AAMA 614 and AAMA 615 offer threeperformance levels for organic coatings: basic performance,high-performance and superior performance, respectively.The table on the following page shows where these standards differ in terms of performance requirements.

Additionally, all three coatings standards set forthequal performance requirements for the following:

n Color uniformity (no variation outside of establishedlimits)

n Dry film hardness (no rupture when tested per ASTMD 3363)

n Dry and wet film adhesion (pass per ASTM D 3359)n Cold crack cycle (15 cycles of exposure to 100°F followed

by exposure to –10°F, with no change in performance)n Oven aging (verifies hardness and adhesion after exposure

to 125°F for seven days then 100% humidity for 4 days)n Heat build-up due to solar radiation (per ASTM D 4803)

Certifying the Completed WindowWindows fabricated from certified extrusions are thentested for conformance to the same structural, air leakageand water penetration requirements for residential andcommercial rating as those imposed on windows withother framing materials. Vinyl products are also tested forspecific quality factors such as strength of the cornerwelds of the fabricated frames.

Fenestration products that have passed these tests andare therefore authorized for certification under the AAMA

Certification Program are listed in the online AAMACertified Products Directory, a valuable resource forarchitects and specifiers. However, products are not actu-ally certified until the manufacturer applies the AAMAGold Label.

Energy Efficiency CertificationFor verification of thermal performance, windows, doorsand skylights are voluntarily tested for conformance tothe NFRC specifications. U-factor and solar heat gain coef-ficient (SHGC) are reported for each product tested.Vinyl’s unique characteristics provide excellent U-factorratings, which translates into energy savings for the consumer. Because AAMA is also one (in fact the largest)of NFRC’s four Licensed Independent Certification andInspection Agencies, authorized to validate tests and simulations and conduct in-plant inspections, windowscan be certified and labeled as NFRC-compliant under theAAMA Certification Program.

Code bodies in some regions of the country nowrequire that windows meet certain U-factor and SHGCrequirements depending on the climatic zone. The DOE’sEnergyStar™ program specifies maximum U-factors andSHGCs for four specifically delineated geographicalregions in the continental United States. Vinyl windowstypically meet Energy Star requirements in all regions ofthe country.

A Proven MaterialWhile all architects are very much aware of the particularcharacteristics of the wide array of building materialsavailable and how those characteristics make a givenmaterial appropriate for a given application, use of today’sperformance standards validates the selection by ensuringthe particular product performs as anticipated. For appli-cations where energy efficiency ranks high on the list, andwhere economy, low maintenance, long-term durabilityand environmental compatibility are important, vinylwindows are an excellent choice.

13

AAMA is a Registered Provider with The American Institute of Architects Continuing EducationSystems. Credit earned on completion of this program will be reported to CES Records for AIAmembers. Certificates of Completion for non-AIA members available upon request.

AAMA Standards for Organic Coatings on Plastic ProfilesAttribute AAMA 613 AAMA 614 AAMA 615

(Basic Pigmented Coatings) (High-Performance) (Superior)Minimum initial dry film 20 microns (0.8 mil) 30 microns (1.2 mil); 25 30 microns (1.2 mil); 25thickness micron (1.0 mil) topcoat micron (1.0 mil) topcoat

where primer is used if primer is usedSpecular gloss Within manufacturer’s Gloss values within ± 5 units of manufacturer’s (per ASTM D 523) recommended values specificationOutdoor Weathering 6 months, 1 year and 2 years 5 years 10 yearsExposure Timesouth Florida)Chalking (after 1 year: Slight chalk 5 years: Chalk: ≤ 8 rating 10 years Chalk: ≤ 8 ratingweathering exposure) (per ASTM D 4214) (per ASTM D 4214)Color Retention (after White: Per ASTM D 4726 5 year fade: ∆E ≤ 5 10 year fade: ∆E ≤ 5weathering exposure) guidelines at 6 months

and 1 year of outdoor weathering exposure. Other colors: ∆E ≤ 5 at6 months, 1 year and 2 years

Gloss Retention after No specification 5 years: ≥ 30% retention 10 years: ≥ 50% retentionweathering exposureErosion Resistance after No specification 5 years: ≤ 10% loss 10 years: ≤ 10% lossweathering exposureImpact Resistance No film removal at initial No film removal from substrate at initial test

test and after impact test (not subject to weathering exposure)at 6 months, 1 year and 2 years of outdoor weathering exposure

Humidity Resistance 1500 hours at 100°F and 3000 hours at 100°F and 4000 hours at 100°F and(test per ASTM D 2247 100% humidity 100% humidity 100% humidityor D 4585; no visually apparent change and “few” blisters ″ size 8 per ASTM D 714)Abrasion Resistance No specification Abrasion coefficient ≥ 20 Abrasion coefficient ≥ 40(per ASTM D 968)Chemical Resistance No loss of adhesion, No loss of adhesion, blistering or visually apparent

blistering or visually change after exposure to muriatic acid, mortar,apparent change after detergent, window cleaner and nitric acid.exposure to muriatic acid,mortar and detergent.

Sealant compatibility No specification Sealant must meet AAMA 800 and have no effect oncoating

Boiling water film adhesion No specification No loss of adhesion after 20 minutes in 212°F waterColor Uniformity No variation outside of limits established by range sample approvalDry Film Hardness No rupture when tested per ASTM D 3363Dry and Wet Adhesion Meet requirements of ASTM D 3359Resistance to 15 cycles of exposure to 100°F followed by exposure to –10°F, with no change Cold Cracking in performanceOven Aging Verify hardness and adhesion after exposure to 140°F for 7 days and then

100% humidity for 4 daysHeat Build-up Record heat build-up due to solar radiation per ASTM D 4803

Please click here to request a subscription to the Vinyl Material Council (VMC) Newsletter to stay apprised of activitiesand developments in the vinyl fenestration market.