,

A seriesof articles

as theyappeared in

the roofing specofficial publication

of the National RoofingContractors Association

~

TABLE OF CONTENTS

.1-3

4-6

... .7-11

.. .12-14

. . 15-18

...19-20

'"'Fibrous Glass Roof Insulation by Edward Mirra, Jr. ,Cellular Glass Roof Insulation by Carl Olm ~.. .Rigid Urethane Foam Roof Insulation by Donald M. Durdan Perlitic Roof Insulation by A. E. Bernardi Extruded Expanded Polystrene Roof Insulation by James P. Sheahan. . .

Composite Board.Roof Insulation by Paul E. Burgess, Jr. . . . . . . . . . . . . . .

NATIONAl AnoFlNG CONTRACTORS ASsoaATION

One O'Hare Centre6250 River RoadRosemont, Illinois 60018(312) 318-NRCA

official publication of the National Roofing ContractorsAssociation.

by Edward Mirra,Jr.

INTRODUCTIONFi~r glass is presumed to have beendiscovered some 10.000 Yt'an agowhen nomadic tribesmen built a hotfire in a bed of sand. The fire meltedthe sand. and presumably atribesman poked a stick -into themolten puddle that appeared. Whenhe pullecd the stick away the meltedsand formcd a long stringy typc

Editor', Note: Edward MirT4, fro iscurrently Section MarketingManager, Roof Insulation, forOwens-Corning Fiberglas Cor-poration. He received his Bachelor ofScience Degree in ElectricalEngineering from Lehigh Unlwrsity,and a Masters Degree in BusinessAdmim:stration from the Universityof Toledo.He has been associated with Owens-Corning Fiberglass since 1962,during which time he has obtainedexperience in many diverse areas ofthe corporation, includingProduction Management, Sales,Market Research, and Finance inaddition to Marketing. Mr. Mirra isa member of the AmericanMarketing Association, AmericanSoa'ety of Heating, Refrigeratingand Air Conditioning Engineers.Professional Engineers Associate.and the Societyfor the Admncementof Management.We are grateful to him for this. our

first in a series of articles on roofl'nsulation.

ROOF INSULATIONfiber. The further he pulled. thethinner it became until suddenly ithardened. Little did he realize thathe had formed the first glass fiber.

Now centuries later. there arenumerous products and applicationsderived from the discovery of theglass fiber. One such product isfibrous glass roof insulation. Today.architects. owners and contractorsare benefiting from the uniqueproperties of glass fibers used toproduce fibrous glass roof insulation.

sulation thickness with thecorresponding maximum flute span.and since alm~t all metal decks haveflute spans of 21,i" or less. fibrousroof insulation can meet practicallyall of the metal deck flute span

requirements.TABLE2:MAXIMUM FLUTE SPAN

PRODUCT Df.SCR.IPTIONFibrous glass roof insulation boardsare composed of glass fibers. Theglass fiber reinforced asphalt andkraft top surface provides the rough,impact. resistant mopping surface forthe built-up roofing system.

Roof insulation boards producedfrom fibrous glass are available in"'x4'sizes, as well as4'x 8' sizes, whichresult in fewer joints in the roofsystem. Fewer joints are purported bymany to provide additional ad-vantages not available with smallersized boards, such as less heat leak-The thickness is varied from ~ ,. to2 v." to achieve the insulation ef-ficiency required as shown in TableI. Double layer application is alsocommonly used to achieve evengreater insulation protection.

FIBER GLASSROOF INSULATION

Max FluteThicknesa Span

Inches Inches

5/4"15/16"1-1/16"1.5/16"1-5/8"

I-S2-12-5S.l4"TABLE 1:

GLASS nBER. R.OOFINSULATIONTHER.MALVALUE SELECTION GUIDE

CA»nductantt R.ailtantt Thickne..11 9.09 2-1/4"

.Ig 7.69 1-7/8"

.15 6.67 1.5/8"

.19 5.26 1-~/16"

.24 4.17 1-1/16"

.27 5.70 15/16"

.56 2.78 5/4"

WIDE FLUTEROOF INSULATION

Max Flute

Thicknea SpanInchea Inchea

2-1/2"

2-7/8"

5-1/4"

4-1/4"

GENERAL DESCIlIPTIONAND USE

Fiber glass roof insulation has twoprimary uses today. First andforemost is its we as a thermal in.sulation to retard the flow of heat.Secondly, it's used as a base for built-up roofing in the construction ofroofing systems for non.~dential

buildings.As the energy crisis continues to

increase in severity, the insulationquality of fibrous glass roof in.sulation is becoming increasinglyimponant in its role of conservingthe nation's vital energy resources, aswell as reducing the operating costsof businesses and institutionsthroughout the United States.

The fine glass fibers from whichroof insulation is manufacturedprovide the very efficient insulatingpropenies of the product. However.a roof insulation product mustexhibit additional properties becauseof the complex forces present in a

roofing system.A unique combination of

properties of fiber glass, not found inany other material, provides thecharacteristics to meet the stringentrequirements of roofing applications.Properties such as strength: weightfor weight, fiber glass has six timesthe breaking strength of steel. Glassfibers are dimensionally stable andwill not expand with heat or swellwith moisture.

In addition, glass fibers arf::flexible, inert and fire resistant,which adds up to an imponant arrayof propenies that are panicularlyhelpful for the long-range per.formance of roof insulation and theentire roofing system.

Fibrous glass roof insulation willvent vapor through the boards.Vapor can be vented or free waterpumped out in the event of damageto the built-up roof, eliminating th~need to remove the insulation shouldit become wet for anyone of manypossible causes. Once the roof in-sulation has been dried, the originalthermal value is restored.

Fibrous glass roof insulation isacceptable and approved by FactoryMutual in accordance with theirpublished requirements. Similarly, itis approved by UnderwritersLaboratories, Inc. for many specificconstruction designs.

The majority of decks beingconstructed p~ntly are metal;therefore, flute span capability ofroof insulation is important. Table 2provides the fiber glass roof in-

I."12"18"12"

5/4"15/16"1-1/16"1-5/16"

HOW FIBROUS -- -

GLASS ROOF INSULATIONIS MANUFACTURED

The first step in the manufacturingprocess of gla~ fiber insulation is tomelt sand. li~one. soda ash andother ingredients at temperatures of25000 Fahrenheit. While the glass isa molten liquid. it flows through tinyholes that shape it into fi~n finerthan human hair. Once the fibergla~ is formed it is spun into lightfluffy material which is than com.pressed into a rigid insulation. Th~insulation then has the reinforcedcover applied. after which it is cut tosize and packaged.

A schematic description of theprocess is shown. but only personalobservation of this manufacturing

operation can vividly depict how farglass fiber technology has progressedsince the tribesmen first discoveredthe phenomenon 10.000 years ago.

APPLICATION OF FIBROUSGLASS ROOF INSULATION

Fibrous glass roof insulation can beinstalled using hot steep asphalt. coldadhesive or mechanical fastenersdepending upon the specific job andits requirements. For metal decks

that are Factory Mutual Class I orclassified as an UnderwritersLaboratories roof deck construction.their respective specific requirements

fJ:~~~~~ ."'WEIGH

MIX

q I

GLASS MELTIN88 REFINING TANK~

~CENTRIFUGEFORMING

~'COMPRESSAND CURE

~=bcrPACK OR CURING OVEN

FABRICATE

MANUFACTURING PROCESS

\0

3

must be followed as they relate toacceptable materials and how theyare installed. One aspect of thelisting of materials for FactoryMutual Class I requires they pass a 60PSF (Pounds per Square Foot) uplifttest. Although Factory Mutual maylist materials for use with fibrousglass roof insulation. themanufacturer's manual should bechecked to see if there are anyrestrictions.

Fibrous glass roof insulation canbe installed over the commonly usedvapor retarder systems. For metaldecks. Factory Mutual and Un-

'--"'L'--"'. ~dl .'dl III I d II II -

lATCH INGREDIENTS H II III

derwriters Laboratories guidelinesshould be followed as required. Themost common roof insulation ap-plication is over a metal deck withoutvapor retarder systems. Glass fiberroof insulation is applied to metaldecks with a 12-15 lbs. per squaremopping of hot steep asphalt. or .7gallons/square of cold adhesive. orby the use of mechanical fastenersbeing applied one fastener for each 2sq. ft. of roof insulation. When vapor

retarders are used. .25-.40 gallons ofcold adhesive is applied below thevapor retarder to adhere it to themetal deck. and. 7 gal. it applied ontop of the vapor retarded to adherethe roof insulation. For poured-in-place and other non-nailable sur-faces. the deck is normally primedusing 1 gal/square of an asphaltprimer. then the insulation is em-bedded in a minimum mopping of 30lbs./square of steep asphalt. Wherejoints exist. precaution must be takento prevent asphalt drippage. Fornailable surfaces. a mopping surfacemust be provided that is adequate toobtain proper adherence of theinsulation. Possible mopping sur-faces might be a base sheet. or a glassfiber felt. or red resin and No. 15felt. These added mopping surfacesare nailed to the deck. and then theroof insulation is adhered to them byusing a solid mopping of hot steelasphalt applied 30 lbs./ square.

Where vapor retarders arerequired over the decks. thosecommonly used are acceptable;however. caution must be exercisedto be certain that the insurance andcode requirements are being met.

...

r

with a c~Uulating ag~nt. Thismixture is placed in a mold andsubj~ct~d to a t~mp~ratur~ of ap-proximat~ly 950°F in a fumac~. Atthis t~mperatur~. th~ glass turns to aliquid. th~ c~llulating ag~ntd~composes. and the mass ~xpandsto fiU th~ mold. This r~sults inmillions of closed c~lIs. containing anin~rt gas. connected to ~ach oth~r toform an insulating mat~rial that isimp~rm~abl~. strong. non-com-bustibl~. and has a constant in-

sulating ~fficiency.

Editor'" Note: Carl Dim is currentlyBusiness Manager, ArchitecturalProducts Division, for P,.ttsburghCorning Corporation. He has beenassociated with Pittsburgh Comingsince 1970, haling previously workedfor Corning Gla.s.s Works in a numberof engineering and manufacturingpositions.

r'"

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CELLULAR GLASS AS AROOF INSULATOR

The function of the insulation in aroof system is to resist the passage ofheat and. to do so, it should alsoresist the passage of water in liquidand vapor form. The insulation mustprovide a strong and stable base forthe membrane and it must becompatible with. and act in concenwith. other materials in the roof

system.As a roof insulator, cellular glass

insulation has advantages because itis:

INTRODUCTIONSince the beginning of time. man hasinstinctively known that water posesthe greatest threat to his en-vironment.

For countless centuries, man usedmaterials provided by natu~ toinsulate himself from water, bothliquid and vapor. He used leaves,wood, and mud. Later, he ex-perimented by using combinations ofthose natural insulators.

He found that if he kept dry, hewas warmer. And, he found thatkeeping water from coming throughthe roof was the key to proper in.sulation. For, without a waterproofroof, it would not be long before hewas left with little protection fromthe heat and cold and wind and sun.

We see the same principle ininsulation today. A wool jacket. forinstance, keeps us warm on a coldday until it gets wet, then it 1<MeS itsinsulating ability. If we rub ourfinger on the inside of a "waterproof'tent when it's raining outside, we robthe tent of its insulating efficiency bypermitting moisture to enter.

We know now that it is importantto protect the deck of our roof fromwater. The insulation we choose forour roof should insulate and protectthe roof membrane, preventing theelements from entering the building.

Impermeable-ASTM Test C -'55ratrs cellular glass insulation as ZeroPerm-In. That means water. eitheras a liquid or vapor. cannotpenetrate the material. Because it isimpermeable. cellular glass in-sulation will not cause blistering orwrinkling of the membrane.

A Constant Efficient Insulator-Because it is impermeable. cellularglass insulation remains unchangedfrom the time it is manufactured;during shipment. while ~ing in-

.1. - "

While with PittsbuTgh Comi1lg, Mr.Olm has held the positions of WorksManager at the company's PoriAllegany, PA, plant, and Man4ger,Market Planning. He ~ named tohis present position, where he directsall markelling activities of the Ar-chitectural Products Division, in1972.Mr. Olm was graduated from theUniverSt"ty of Pittsburgh with aBachelor of Science Degree in In-dustrial Engineering. He is amember of the Amen'can Instl"tute ofIndustn'al Engineers, the A mencanSociety of ProfeSSIonal Salesmen, andthe Resenle Officer's Association.

We are grateful to Mr. Olm for this,our second in a sen'es of articles onroof insulation.

DESCRIPTION OFCELLULAR GLASS

The manufacturing process forcellular glass insulation consists ofcombining crushed glass. which has avery closely controlled chemicalcomposition and physical pro~nies.

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4

Ct'l/ular gia.ss has a compression strength of over seven tons per square foot

stalled, and while in service. It'sguaranteed to retain its originalinsulating efficiency for 20 years,

Dimensionally Stable- A lowcoefficient of expansion insures thatcellular glass insulation will notgrow, shrink, warp, or buckle, Itdoes not contribute to those forcesthat the membrane must resist toprevent splitting or wrinkling.

Noncombustible - Cellular glassinsulation is approved by FM forClass I Construction and by V.L. forConstruction Nos. 1 and 2. Itrequires no special protection duringstorage or application to prevent itsignition or to prevent it frommelting. It can't give off any lethalfumes, of course, because it can'tignite.

Light Weight-Because it weighsonly nine pounds per cubic foot, thematerials requires no extra deck orstructural frame construction and iseastily handled by the roofingcontractor. Its light weight makes itideal for reroofing applicationswhere the deck and structural framewill not permit the weight of heaviertypes of insulation.

Pittsburgh Corning was one of theearly advocates of positive roofdrainage and was the pioneer intapered insulation systems, acommonly accepted design criteriatoday. The Tapered Roof InsulationSystem consists of a series of in-sulation blocks placed in a specificsequence to form a slope of 1/16",liS", 1/4" or 1/2" per foot. Eachinsulation block is factory tapered,identified as to its place in thesequence, and is marked as to thedirection of slope. Most projects canbe designed to achieve a single in-sulation layer.

Foamglas Board is made inmodules 2' x 4'; in thicknesses from11,2" through 4"; and 1,2" in-crements.

Foamglas Flat Blocks come inthicknesses from 11,2" through 4" (in1,2" increments). Sizes are 12" x IS"and IS" x 24".

All three forms of Foamglas in-sulation can be installed on all decksurfaces, the most common beingsteel, concrete or wood. The in-sulation is installed using con-ventional roofing practices,adhesives. fasteners and equipment.The material is installed solely by theroofing contractor, thus insuring onecontractor responsibility.

MANUFACTURED INTHREE FORMS

Cellular glass insulation ismanufactured by the PittsburghCorning Corporation. under theregistered brand name Foamglas. inthree forms: flat boards. flat blocksand tapered blocks.

CONCLUSIONWith today's soaring costs and in.creased consumption of energy. it L-;imperative that roofing contractors.

owners, and designers be fully awareof the injurious effects water andwater vapor have on the materialsused in roofing systems.

Ignoring those effects. whenselecting materials. will cause bothexcessive consumption of energy andearly failure of the roof system.

5

A t,PI.cal TapeTed Foamglas Roof Insulation System is being installedon this metal deck using conventional TOOftng pactices.

Cellular glass is impermeable. Water, either as a liqw'd or wpor,cannot penetrate the tn4terial.

~T8~~~~~:TJIO:".-"-".. PER FOOT TAPER

H"

I ,. =~1;~:2;tIHlH1~~;~Q~bI:1:-z.'

This illwtration indicates that on a J /S" slope, the tapered blocks arepositioned single-layer JfJr 28 Jeet. Then, the same sequence is repeatedwith the addition oJ a J~ -inch thick foam,;las-Board underlayment.

(

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6

IntroductionHistorically. the great advances in architecture have beensparked not so much by radical discoveries in newmethods of building. but rather by the evolution of newkinds of building materials. In time. wood. stone andmetals emerged as the tripod upon which the wholestructure of building technology rested.

In the past couple of decades. however. science hasadded a new dimension to these time-tested buildingmaterials. Its ease of adaptability has been astoundingmore than just historians. This new dimension comprisesthe spectrum of plastic materials - and more specificallyfor this article - rigid urethane foam.

Editor's Note: Donald M. Durdan is techm'cal productrepresentative for rigid foam chemicals in thePolyurethane Division of Mobay Chenucal Corporation,p"ttsburgh, Pa.

Prior to jol-mng Mobay in January 1975, Durdan wassales representative with E. I. DuPont de NemouTS S Co.and senior industrial sales representative with ExxonChemical Co.

Re is a graduate of Bethany College, Bethany, W. Ya.,where he received a bachelor of sCIence degree inchemistry.

Mobay Chemical Corporation manufacturesisocyanates and polyols, chemicals basic to themanufacture of urethane foam spray systems andboardstock products, which are increasa"ngly used toinsulate commen'cal, industrial, and institutionalbUt'ldings, hot oil PIpelines, and storage tanks.

We are grateful to Mr. Durdan for this, our third in asenes on roof insulation.

Rigid Urethane Foam... What It IIRigid urethane foam is a synthetic cellular plastic whosebasic ingredients of manufacture are created by manthrough chemistry.

Technically speaking. urethane foam is formed by the

0,;- Laboratory Demonstration Of Basic Foam Production Process - These Photographs iUustrate the basic foamingprocess, (1) The two u'qu,a chemical components are combined, (2) agl°tated for thorough blending, (J) pouTed into areceptacle where the foaming reaction begins immediately, , ,

7

ttaction of two liquid chemicals (isocyanates and polyols)in the presence of certain additives and catalytic agents.The mixtutt begins to foam instantly and quickly ex-pands to about 50 times its original volume. The foam

completely fills the area, space or cavity to be insulatedand hardens into an air-tight mas. It becomes tack.freein minutes, and is totally cured in 12 houri. Thereafter,the foam, one of the most inert of chemical compounds.is stable and retains its thermal and other resistiveproperties alm~t indefinitely. when it has been properlyinstalled.

Urethane's superior insulating ability derives from thehigh concentration of fluorocarbon vapor - more than 95per cent of the material's volume-generated during thefoaming reaction. The vapor. trapped in the foam'smillions of tiny cells. has ~xtremely low heat conductanceand keeps internal convection to a minimum. The closedcell structure is only slightly permeable to air and water

vapors.Rigid urethane foam is not a single material; rather it

is a family of materials with different formulations for

specific applications.

Which Application MethodToUIe

Urethane insulation can be foamed-in-place at thebuilding site by pouring or spraying the liquid com-ponents. or it can be factory-produced and delivered tothe job site for installation as laminated slab boardstock.insulated building panels. doors. siding and otherproducts. The foam-in-place techniques are useful ininsulating roofs, walls and other elements in new con-struction or hard-to-reach areas in existing buildings.Because urethane foam is produced from liquid com-ponents occupying 1/30 the volume of the expanded

. . .and (4,'> uparLsa.on continues until (6) the rise iscompleted. Foam is tackjree shortly aftn completIOn ofthe rise. The rigid foam it JO times the volume of theoriginal chemicals, leading to savings in shIpping,handh'ng costs.

0PhotomiC1'ogTaph shows the netwOTi of closed cells whichgives rigid urethane foam its unusual strength andsuperior insulating wlue. There are about 1,000 cells in aone-inch cube.

8

material. substantial savings in shipping. inventory andmaterial handling costs are realized.

Pouring: This is an excellent method for installing astrong. seamless core of rigid urethane in wall cavities.The foam fills all angles and comers of any space orcavity, going under pipes, around comers and intocrevices.

Spraying: Large open surfaces, such as roofs, can becovered with sprayed-on layers of rigid urethane, usingspecial gun.type apparatuses. The chemical componentsare mixed and atomized as they are sprayed. To attainthe desired thickness, thin layers are sprayed on suc.cessively. each adhering to the surface below, hardening,curing and sealing rapidly. Once applied and as soon asfully cured. the urethane should be properly protectedfrom fire, moisture, and ultraviolet lights.

~

value (7.14), rigid urethane foam insulation providesexcellent thermal resistance.

The properties of urethane roof insulation yield anumber of advantages for roofing contracton, buildingownen, and architects. Some of these include:

-Thermal Resistance: Makes possible reduction insize-and cost-of original HVAC equipment and ductwork; lowen HV AC operating costs; conserves energyexpended for heating and cooling; means that a singlelayer of insulating material is usually sufficient to achievespecified R-value-

-Light Weight: Can reduce the dead load of a roof byup to 75 percent, leads to savings in installation time andlabor, and has good compressive strength to resist heavyloads.

-Minimum Water Absorption: The stable, strongstructure of rigid urethane foam locks out water

penetration.-Low Water Vapor Permeability: Rigid urethane

foam has a moisture-permeability rating in the range ofone to three perm-inches, depending on density andformulation. However, urethane foam is not a vaporbarrier. A separate vapor barrier should be specified inhigh humidity situations, where outdoor temperaturesare frequently below freezing and in cold storage plantswhere temperatures of 32 OF or lower are standard.

-Dimensional Stability: Even under a wide range oftemperatures (225°F to -4000F) and humidity, rigidurethane foam does not shrink or expand to form voids ordead spots which would reduce insulating efficiency-

-Venatility of Foams: In addition to being able tospray-or pour-in-place, urethane board roof insulationis manufactured in a variety of forms that make thematerial acceptable for almost any kind of deck, shapeand situation. In addition to conventional laminatedurethane boardstock of various thicknesses, there areavailable for special situations: 1) Composites whichcombine urethane with a fire-rated material. such asperlite board, glass fiber or gypsum board, to makeinsulation acceptable for metal deck, Factory MutualClass I construction; 2) laminated high-density foams foruse on plazas or load-bearing decks; 3) tapered laminatedboard for easy sloping of flat decks; and 4) compositeboard of such strength that it serves as a structural, in-sulated roof deck.

--Most of todays polyurethane technology is based onproduction and process techm"ques developed by MobayChemical Corporation and its parent company in WestGermany" Here," energy-saving n"ga"d urethane foampanels for lam'"nated sheathing aPPlications and roofinsulation are belOng produced and emluated at MobaysPilot plant/application development operation in Pitts-burgh, Pa"

Boardstock or Slabstock: This rigid urethane foam isproduced at a factory where it is cut into flat sheets ofdifferent thicknesses (generally %" to 3 ~ ") and standardsizes (generally S' x 4' or 4' x S')" Protective coatings,mastics, paints, or structural or decorative skins areapplied in the manufacturing process. As a roofingmaterial, it goes down fast and the roofer needs noadhesives other than those required for most roof in-sulating materials. It's easy to cut to fit around drains,vents, other obstructions; however, bare urethane foamshould not butt against metal chimneys. Factory-made,laminated board is being increasingly specified as roofinsulation"

I').,'W

Energy ConservationComfort conditioning requirements of modem buildingsmandate the design and construction of roof aaembliesthat make the most effective we of heating. ventilatingand air conditioning systems.

With no doors or windows to consider in thecalculations, the thermal performance of a roof can beupgraded simply by specifying sufficient roof insulationto meet energy conservation standards. Figure 1demonstrates how adding insulation to an uninsulatedroof can bring about a significant reduction in heattransmission.

A key example of urethane's energy-saving capabilitiesis that a 1" thickness of urethane-board roof insulationsupplies the same thermal resistance (R) as 1 *" of glassfiber, 2 ~" of foam glass or 2 ~" of perlite. Figure 2

Properties and PerformanceCharacteristics

The roof is a critical area in building design, constructionand perfonnance. A successful roof protects thebuilding's occupants and contents from the weather-summer and winter. It helps to make heating, ventilatingand air conditioning systems workable and economicallyfeasible.

Good insulation, properly installed, is an essentialfactor in helping to insure long-tenD success of the roofassembly. With a designed k.factor of 0.14 and a high R.

9

HIMIf' IEAT l8IIWITH AND WITHOUT _uno.

~IGN CONDITIONS: 10,CXXIoq ft, 2" Iw.-gill -- roof d8ok.~ rooIng, WF temper.I",. dIn_- III I) CaIcuIMioI8 do .--.cIud8 .. ... « - surface .Iill ..

illustrates how thick these insulating materials must be toachieve an R- 7 .14 value.

Figure ~ shows how urethane roof insulation and otherinsulating materials cut heat losses in four different typesof roof decks. The figures apply to a roof area of 100,000sq. ft.; temperature differential is 60°F. Calculations donot include air film or inside surface still air.

If there are circumstances which demand thinner roofsor walls, urethane-with its superior insulatingcapability - makes it possible to reduce the thickness ofthe insulation component with no 1011 of thermalresistance. Or. the thermal resistance of an auembly canbe increased without enlarging the size of the member.Urethane helps to offset the design restrictions imposedby the fact that most building materials are constant inthickness and weight.

-~.-~

=.,--ConcI8d81*

T*RU""'ot.-

--~~

-~~~

=-~Cancl8d.:t

TOI8I AU ~raaf

~I-.~

.~

eaI.a[Ii

0.8

r °For8lUl8 lOt """'ning '-I k-.: U x to t x Area - en.-No ~: 0..- x eo x lo.cq - 234.

WIII~: o.~ x. x lo.cq - 81.

E-w -'ng with minIm8/ NIl.ion: 8PIIIOx"""", ~

I,".

I;.

FIG. 1

THICKNESS FOR EQUIVALENTTHERMAL RESISTANCE

Urethane and Fire SafetyUrethanes. like all other organic materiala. are com-bustible. Precautions must be taken to insure that goodfire safety practices are observed in design. installationand storage. wherever urethanes, including those con-taining flame retardents, are used.

When used over concrete, poured gypsum or tongue-and -groove wood roof decks. urethane normally does notalter the fire hazard rating of the building, but it must bepart of a Class A, B or C assembly.

If urethane foam is specified for a metal roof deck orfor a roof that is subject to fire exposure from below. andunderlay of perlite, gypsum board or other fire-ratedmaterial in most cases must be installed between the deckand the foam. Recently, an isocyanurate bued material(modification of the Itandard urethane chemistry) hasbeen accepted in Factory Mutual Class I Construction asa non-composite material.

Other recommendations on the safe use of urethanesare contained in "Fire Safety Guidelines for Use of RigidUrethane Foam Insulation in Building Construction, ,.

published by Urethane Safety Group, The Society of thePlastics Industry, Inc.. ~55 Lexington Avenue, NewYork. NY 10017.

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..

0Sprayed-on urethane foam, when properly instaUed, canbe wed to insulate roof decks. The material is especiallyaPPll'cable to hyperbolic paraboloid roofs such as the onein this photo, After it hardens. the foam must be coatedto protect it from weathering.

FIG. 2

10

COMPARATIVE ENERGY-SAVING EFFECTIVENESS

RoofConstructiop

Heat LossUninsulated

Heat LossWith Insulation

1" Urethane(R=7.14)

1 H Glass Fiber

(R=4.00)1" Foam Glass

(R=2.86)

1 H Perlite(R = 2.56)

Metal Roof Deck.+ BUR

fR = 0.33)8O2.800BTUH18,180,OOOBTUH

2- Poured GypsumDeck + BUR+ Vapor Barrier

(R=1.65)3.660.000 660,000 1.~1.947 1,320,OOC 1.425,178

2M Wood+ BUR+ Vapor Barrier

(R = 2.48)925,925 1,122,000 1,190,4782,400,CXK) 624,000

2" lightweightConcrete + BUR

(R=2.55)1,174,168618,000 916,(KK) 1,O8O,(XXt2,340,000

.If urethane Is used to Insulate a metal roof deck, the insulating system must include a fire-rated material such as perlite, glass fiber or gypsum board as the base. See page 14.

FIG. J ...

r.,;'"

by A. E. Bernardi

Typical deposit of perlite ore with soil overburdenremoved.

Perlite ore is a volcanic glass found in abundance in themountainous areas of the West and other areas of theworld. It is extracted from the grip of Mother Earth byastrip mining process, crushed, screened, and graded forultimate expansion into particle sizes suitable for a varityof uses.

It has been said that expanded perlite was discoveredby accident when a dissipated and despondentprospector, while sitting at his camp fire one night, threwa handful of perlite ore into the fire in a gesture of disgust,and much to his amazement it popped or expanded.

Whether that is fact or fiction, perlite ore in its naturalstate ranges in color from a transparent light gray to aglossy black and has a combined water content of two tosix per cent. It is the latter characteristic which causesperlite ore to expand from four to twen~ times its volumewhen subjected to a furnacing temperature of ap-proximately 1700oF. At that temperature, the combinedwater vaporizes and the ore expands or "pops" intocountless snowy white to grayish miniscule non-conductive glass spheroids which account for the ex-cellent thermal insulation of expanded perlite.

Typical uses of expanded perlite are as a lightweightaggregate in concrete, loose fill insulation, plasteraggregate, pipe insulation, foundry sand additive.filteraid, and a multiplicity of other applications bothwithin and outside of the construction industry.

Expanded perlite ore is the principal ingredient inperlitic roof insulation. An acqueous slurry comprised ofexpanded perlite, cellulosic fiber, asphalt and possibly

12

starch is formulated and deposited in the head box of aFourdrinier Machine. From the headbox. it is moved onto a moving screen which forms a wet mat from the slurrysolids. The wet mat is dewatered and subjected to ex-ternal heat in an oven or dryer.

As the dry mat exits the dryer, it is sized into piecesmeasuring 2' x 4' by a series of gang saws, stacked,wrapped, and unitized for mechanical handling.

Perlite Ore

Fourdrinier Machine"

,0 I I "fc.

Saws

Crushed Perlite OrePerlite roof insulation is designed for use over nailable,

non-nailable, and steel roof decks. It provides adimensionally stable thermally resistant surface for theapplication of built-up roofing, and it may be applied to asteel deck with hot or emulsified asphalt, solventadhesive, or mechanical fasteners.

The top surface of perlitic roof insulation is treated tominimize bitumen absorption and provide an intimatebond with built-up roofing. It is light weight, is easy to cutor contour, has a high resistance to moisture, has nocapillarity and is resistant to compression or indentationfrom normal on the job traffic of roofers and themechanical equipment frequently used in the process ofinstalling a built-up roof.

Perlitic roof insulation is an approved component ofClass I Insulated Steel Deck Construction and severalspecific construction desgins as described by FactoryMutual System and Underwriters Laboratories Inc.respectively.

It has a flame spread of 25 which is derived in com.parison with untreated red oak as 100 and asbestoscement board as 0 during exposure to lire under con-

Expanded Perlite Ore

The three stages of processing one ounce of perlite oreillustrate the volumetric increase upon furnacing.

13

MANUFACTURING PROCESS OFPERLITIC ROOF INSULATION

~

trolled conditions in accordance with UnderwritersLaboratories Inc. Standard Test Method for Fire HazardClassification of Building Materials (UL 723).

It is manufactured in compliance with FEDERALSPECIFICATION INSULATION BOARD. THERMAL(MINERAL AGGREGATE) HH-I-529B and in ac-cordance with the U.S. Department of Commerce"Simpllfied Practice Recommendation R257-55 ThermalConductance Factors for Preformed Above-Deck RoofInsulation" requiring a thermal conductance "C" of .36for a nominal 1" thickness.

Although other nominal thicknesses of perlitic roofinsulation have been made available from time to time,the following represents those commonly manufacturedwith applicable thermal conductance and resistancevalues:

Dual layer application of perlitlc roof insulation withstaggered joints is customary in those instances where athermal resistance value exceeding that achievable with asingle layer applkation is desired ot because It is thoughtto reduce heat loss and ridging of the built-up roofingmembrane over the joints.

Perlitic roof insulation is used extensively as a substratefor polyurethane foam in the production of compositeroof insulation because of Its fire resistive quality. It is alsofrequently used in the field as the Initial layer of roofinsulation over which is then applied a polyurethane orpolystyrene roof insulation with staggered joints.

Good roofing practice dictates that roof Insulation ofwhatever type should be kept dry before, during, andafter installation, and perlltic roof Insulation is no ex-ception. At the jobslte, It should be stored on risers atgrade level or on the structural deck and covered withtarpaulins, and no more of It should be installed than canbe completely covered with built-up roofing the sameday. . . .

NominalThk:kness

3/4"1"

11/2"2"

ThermalConductance

.48

.36

.24

.19

ThermalResistance

2.082.784.175.26

14

()

cumstances In this case warrant It. This Isnot. of course, on endorsement on theport of NRCA. but rather a recognition ofthe existing market conditions.)

Editor'. Note; This article, fifth in ourseries on roof insulation, is presented byJames P. Sheahan, Roofing IndustrySpecialist for The Dow ChemicalCompany, Midland, Michigan.

Mr. Sheahan graduated from theUniuerslty of Toledo In 1953 with a B.S.in Chemical Engineering. He worked inthe plastics section of Douglas Aircraftfrom 1953-55, working with ther-moplastics and reinforced plastics. From1955 through 1959, he 5ertled as anauiator in the U.S. Nauy. In 1959, hejoined The Dow Chemical Company,and has been associated with plasticfoams, primarily extruded polystyrenefoams as related to the constructionmarket, euer since. He has been par-ticularly concerned with roofing duringthe entire period.

Mr. Sheahan has had responsibi/itJesin technical serulce, research anddeuelopment, market deuelopment,market research and marketing. In hispresent position, he is concerned withDow and Industry producls worldwide.We are Indebted to Jim for his time andeffort in preparing the article that follows.

(Since The Dow Chemical Companyis the sole manufacturer of extrudedexpanded polystyrene roof insulation,the term STYROFOAM brand insulationappears frequently throughout this ar-ticle. While our normal publishing policyis to restrict the use of brand names andtrademarks, we feel thot the ci,-

INTRODUCTION

STYROFOAM. RM brand Insulation isan exbuded, expanded pol~ene,designed for use as roof insulation. It isnot a new product. The original patentsfor expanded polystyrene date back to1931. The first material designated asSTYROFOAM was produced in the1940's during World War " for use as aflotation medium. The lightweight, closed

ceO. water-resistant foam possessed idealproperties for flotation. In 1948. the firstcommercial structure insulated withSTYROFOAM brand insulation wasconstructed. It was a low temperaturespace warehouse. The traditional mat-erial. cork. was replaced with STY-ROFOAM brand insulation becausethe closed ceO characteristic developed abetter insulation value requiring lessthickness. and long-term insulatingperformance because of the resistance tothe entrance of water. The rigid structureallowed finishes to be installed fora protective surface. These attributes.coupled with the fact there was ashortage of cork. provided the first in-road of STYROFOAM brand polystyrenefoam as an insulation material.

Many uses developed over the yearsbased on the unique properties inherentto this material. For non-insulatingpurposes. in addition to flotation. the useof the material in f\oraJ and noveltyend uses Is familiar to most people.STYROFOAM brand plastic foam hashad much greater use as an insulation.starting with low temperature spacebuildings and spreading to walls androofs of commercial buildings. sheathingfor agrkuhural buildings. sheathing forresidential buildings. covering of tanks

"Trademark of The Dow ChemicalCompany

IS

~

c

on the top and bottom surface, im-proving the strength properties of theproduct, particularly the compressivestrength. The final product is a ruggedboard that can take abuse during in-stallation and provide long-term per-formance properties of high insulationvalue even when subjected to thetemperature and moisture extremes ofthe weather.

PROPERTIES OF STYROFOAMBRAND INSULATION

It has been over 30 years sinceSTYROFOAM brand plastic foam wasfirst considered as an insulation materialbecause of its predictable long-terminsulation performance. Unansweredquestions at that time were: whether thematerial had sufficient structural integrityto resist the rigors of construction, asufficiently high end use temperaturelimitation, and adequate resistance tocombustibility. These questions wereanswered in the affirmative. Theproperties of STYROFOAM RM havebeen tested over the years in thelaboratory and by field experience toprove the material can be used suc-cessfully in construction by following thespecifications of the manufacturer.STYROFOAM brand insulation has beenused in many forms in many constructionapplications where each property hasbeen tested and not found to be wanting.The following describes the charac-teristics of various forms of STYRO-FOAM brand insulation.

WATER RELATED PROPERTIESThe polymer is water-resistant and theclosed cell structure provides amechanical barrier to the entrance ofwater. Water is the "Achilles Heel" ofmost insulations. With some types ofinsulations, water degrades the materialto the point of losing its structuralproperties. This is of particular im-portance when the insulation is used as abase for the built up roof or as theprotection for the built up roof as in theprotected membrane assembly. Thereare a number of mechanisms by whichwater can affect insulation and manyexamples, some with 30 years of history,demonstrate that STYROFOAM RMbrand insulation is essentially unaffectedby water.Water Absorption 0.55% by Volume(ASTM 02842.69)Water absorption is kept to a minimumbecause the polystyrene material isresistant to water, and the closed cellstructure inhibits the entrance of water.This quality has been demonstrated inthe flotation market where docks and ~

16

and vessels in the industrial market andbelow grade for building foundations andas an underlayment for highways.

While there is little confusion indistinguishing between plastic foaminsulations and the more familiar fibrousinsulations, there is a tendency to notrecognize the differences betweenvarious plastic foams. Just as there aredifferences in the properties of the fibrousinsulations, there are very specific andmeaningful differences between plasticfoams. Three of the most popular typesare reviewed for clarification.

STYROFOAM brand insulation isextruded, expandt.d polystyrene. Theextrusion process produces a continuousflow of material of interconnecting closedcells. The process may be consideredsomewhat akin to shaving cream orwhipping cream obtained from apressurized canister. The polymer isexpanded about 30 times, providing adensity of about 2 Ibs./cu. ft. The cellsare expanded with a gas that is retained.providing a low insulation value rated at aK of 0.20 BUT in/hr/ft2 /oF at a meantemperature of 75°F (resistance - 5.0).The insulation value tends to remainconstant in usage, even when exposed tohigh humidity conditions. The polymeris considered to be hydrophobic, i.e.water-hating, and works in conjunctionwith the closed cell structure to providelong-term water resistant properties.The polystyrene is affected by mostorganic solvents and it will bum.

Molded board or beadboard is alsobased on polystyrene polymer and isexpanded up to 60 times, providing adensity of about 1 Ib./cu. ft. Higherdensities can also be produced. Themajor difference in the productionprocess is that small beads are fused ormolded together much like in popcornballs. The properties are for the most partdependent on how well the beads arefused to each other. The cells are tiDedwith air, resulting in a K factor of .24 (R- 4.2). The insulation value tends toremain constant unless subjected to highmoisture conditions. Most often, theprocess is batch vs. continuous wherelarge billets are slabbed into boards;however, molded boards can beproduced on a continuous basis. Thismaterial is also affected by organicsolvents and will burn.

Urethane foam is based on a differentpolymer, which is thermo-setting. Thismeans that'once it is formed, it cannot bereverted to its original shape as can apolystyrene foam which is thermo-plastic. The urethane polymer will burn.but is more resistant to solvents and maybe used at higher temperatures. It is

usually expanded to a 21b. / cu. ft. densityby casting by batch or continuous processproducing large billets from which boardscan be cut. Also, it can be cast andlaminated in a continuous process. Theprocess is similar to making a cake,where ingredients are mixed and areaction takes place producing a rigidfoam with cells filled with a captive gasproducing a very efficient insulation valuerating of K - .16 (R = 6.2). The in-sulation efficiency tends to decrease withtime, especially when subjected to highmoisture conditions. Various skins, suchas metal foil and roofing felts laminated tothe foam improve the long-term in-sulation performance.

The different processes and polymersproduce very different foams. A moredetailed explanation of the process toproduce STYROFOAM follows to assistin understanding how its properties aredesigned for a particular end use, namelyroof insulation-

PROCESS

The raw material, styrene, is made fromderivatives of coke and crude oil. It ispolymerized to form polystyrene. Asolution of blowing agent in moltenpolystyrene is formed in an extruderunder pressure and this solution is forcedthrough an orifice into ambient tem-perature and pressure. The blowingagent then vaporizes and causes thepolymer to expand. The polymer issimultaneously expanded and cooledunder such conditions that the polymerdevelops enough strength to maintaindimensional stability at the time ofmaximum expansion.

In the first days of production, largebillets were formed and cut into lengths ofapproximately 9 ft., and stored outdoorsfor several weeks to allow equalization ofthe pressure in the cells. After curing, thebillets were treated much like lumber andsawed to appropriate board and blockshapes. This process was modified in the1950's to extrude a modified billet,slabbed to size, and cured at an elevatedtemperature to bring about a more rapidequalization of the air in the cells. In theearly 1960's, the process was modifiedagain utilizing a captive blowing agentsystem. The new blowing agent im-proved insulation efficiency, whichoriginally was K - .36 to .20. Coin-cidental with this change, boards wereextruded to size, varying from 3/4" to31Ji' in thickness. The boards are up to 4'wide and to 9' long. Boards used as roofinsulation are cut to 2' x 4' and theproduct identified as STYROFOAM RMbrand insulation.

Boards extruded to size provide a skin~

"CC';", "";~' c'

ROOF INSULAT I ONmarinas have been floating high and dryfor decades.Moisture Vapor Tran.miasion 0.4Perm-Inch (ASTM C-355-64)The multi-celled structure and the highdensity skin of the roof insulation productcombine to form a product that has alow vapor transmission. Water isprevented from entering when the in-sulation is subjected to vapor pressuredifferentials which exist in every con-struction end use, particularly roofing.The moisture vapor transmission ofSTYROFOAM br-and insulation Is lessthan 1 perm which, by rule of thumb, isconsidered to be a vapor barTier.STYROFOAM brand insulation can pickup water under extreme conditions ofhigh moisture vapor drive for long timeperiods, especiaOy when the vaporbarrier (in applying the built-up roof) is onthe cold side, as it is in conventionalroofing. However, applications in lowtemperature space and industrial enduses have shown the material performssuccessfully when exposed to thiscondition without a meaningful loss ininsulation value.Freae/Thaw Cycling 3~ byVolume Water PIckup After 1000Cycles (ASTM 666-73)The integrity of the ceO structure resistsdegradation by freeze/thawing action ofwater, which will destroy more rigidglass-like Insulations. Use over 15 yearsin earth insulation applications. such as abase for highways, has demonstrated thematerial resists degradation by thismethod of attack by water.Humid Aging 3% ChangeIn Volume(Federal Specification H.H.I. 524b)The hydrophobic qualities of the polymercombined with the closed cell structureprevent the Ingress of water due toexposure to hot, humid conditions.Under conditions of 100% humidity and140°F, the insulation has the quality tonot only prevent the loss of insulationvalue, but to resist change in volume,therefore maintaining good dimensionalstability. Performance when exposed tothese conditions has been demonstratedby the use of the material as a base forroofing, where water has gained entranceinto the roofing system, and in theprotected membr-ane assembly where theinsulation is exposed directly to suchconditions.

Aged Insulation Value 0.20 BTU-In/Hr/Ft2 ;OF at 75°F Meon(ASTM C-177-71)The foregoing demonstrates thematerial's resistance to water pickup Thisresistance to water plus the ability to

~7

contain the gas within the closed cellstructure insures a predictable long-terminsulation value.

TEMPERATURE RELATEDPROPERTIESPolystyrene is a visoelastic material,which means It displays a broad range ofthermal behavior when heated aboveroom temperature. The first level ofInterest is the heat distortion point{l65°FJ which is diS4..ussed thoroughly inthe next paragraph. At about 240°F itcan be deformed if a k>ad is applied for ashoo time, but tends to recover its shapewhen the load is removed. Above 480°Fthe polymer softens and flows. The flashignition point is 690°F and self-ignitionoccurs at 735°F

Heat Distortion Point 165°F(Manufacturer's Method)The recommended maximum end usetemperature of STYROFOAM tM'andInsulation is related to its heat distortionpoint. The 165°F is based on exposureof the entire board in an oven to atemperature where no physkal change inshape is noted. This is a control tn thatby experience can be relilled 10 success-ful field experience. For example,STYROFOAM RM bla~ri insulation canbe b:ought directly Into contact withasphalt at 325O! by use of a roll coater toapply 10 Ibs/ft of asphalt to its surface.It can also be brought Into direct contactwith asphalt that has been mopped to adeck, because the mass of the asphalt isreduced by flowing to a thin layer,allowing the material to quickly reduce Intemperature to 250°F. This allows in-stallation without mehlng or distorting ofthe board. Because black roof surfacescan reach temperatures of 180°F, onlygravel surfaced roofs were spectfled to beinstalled over STYROFOAM RM b:andinsulation. While care must be exercisedby the contractor while working withSTYROFOAM brand insulation in directcontact with hot asphalt, techniques weredeveloped to adhere the insulation tovarious str\Jctures and to a built up roofwithout deterioration. Because of thestructural integrity of the STYROFOAMRM brand Insulation, when properlyInstalled, the ultimate bond to con-struction materials is strong both intension and shear.

Coefficient of Expansion/Contraction35 oX 106 In/In/oF From -30°Fto lsooF (Manufacturer's Method)The coefficient of expansion/contractionof plastic foams is generally higher. 2 to 8times, than most roofing materials.However, as with all insulation materials,the temperature differential to which it is

exposed Is cut in half, thereby redudngpredicted movement by one-half.Further. the size of the insulation board Is2 ft. x 4 ft., so the total change indimension due to temperature change islimited. Adhering the material to thestrudure impedes movement significantlybecause STYROFOAM brand plasticfoam is not sufficiently strong to over-power the bond of the adhesive.

STRENGTH PROPERTIES(Manufacturer's Method)

Tensile Modulus 3,800 psiTensile Strength 90 psiCompressive Modulus 2,400 psiCompressive Strength 45 psi

The physical properties of STY-ROFOAM brand insulation are lower(1/4 - 1/10) than most roofing materials.

Also, the strength properties generallyremain unchanged by changes intemperature where most buildingproducts demonstrate a marked increasein strength properties at cold tem-peratures.

The tensile strength Is an Importantconsideration for long-term performance,when combined with the coefficient ofexpansion / contraction. These propertiesdetermine the force that could betransmitted to adjacent building mat-erials, such as a built-up roof instaUeddirectly to the Insulation. WhileSTYROFOAM brand Insulation tends tohave a high rate of movement, i.e., straindue to temperature change, the force,i.e. stress developed, Is low because of itslow tensile strength.

While the strength properties areconsidered to be low, the density of theproduct Is maintained in excess of 2 lb. / cu .ft. for roof insulation. This 8O0ws thematerial to be used successfully by theconstruction trades and to perform long-term by resisting the rigors to which It Isexposed. In particular, the compressivestrength Is equal to or better than mostrigid roof insulatk>n boards. Experiencehas shown It has served well as a supportfor roofing membranes subjected to rooftraffic and as the base for finishes varyingfrom loose stone to concrete pavement.SOLVENT RElATEDPROPERTIESPolysryrene based products can bedissolved by most organic solvents. Thereaction intensifies with an increase intemperature. When STYROFOAMbrand insulation is recommended for usein direct contact with solvent basedadhesives, waterproofing or flashingmaterials, specific directions must befollowed. Coal tar pitch can be used withSTYROFOAM RM brand insulationwhere long-term exposure does notexceed 100°F.

~

(

~

18

FIRE RELATED PROPERTIESAlthough STYROFOAM brand in-sulation contains a flame retardantadditive to inhibit accidental ignition fromsmall fire sources, it is combustible andmay constitute a fire hazard if improperlyused or installed. During shipping,storage, installation and use, this materialmust not be exposed to open flame orother ignition sources. Consult The DowChemical Company's literature forspecific use instructions.

In testing designed to measure theresistance of a deck assembly (struc-ture/insulation/built-up roof) to externalfire, including burning brands falling onthe roof, under high wind and varyingslope conditions, the roofs constructedwith STYROFOAM RM brand insulationas the base of the buih-up roof and abovethe built-up roof in the protectedmembrane assembly qualified for a ClassA rating by Underwriters' Laboratories.

In testing designed to measure theresistance of a deck assembly to internalfire, the protected membrane assemblyutilizing STYROFOAM brand insulationqualified for many additional ratings.Additional information is available fromthe testing organizations involved or TheDow Chemical Company.

APPUCATION INROOFING SYSTEMS

STYROFOAM brand polystyrene foam,in various forms, was used as a roofinsulation as early as 1948 as the base forbuilt-up roofing, and has been used since1968 in the protected membraneassembly. It is useful to trace the historyof these two methods of installation tounderstand the evolution to the presentsystem. Through its long history, workhas concentrated on methods of in-stallation that made the insulation with itslimited end use temperature compatiblewith normal methods of construction of aBUR.

Initially, boards cut from large logswere attached to decks with hot asphaltor nails. Some form of thermal barrierwas applied over the insulation beforeapplying the BUR. Materials such as 1/2"thick layer of cement mortar were usedfirst. Later on fiberboard roof insulationwas mopped and flopped on the foam todevelop a more economical system. Thissystem is still recommended by variousmanufacturers of polystyrene foam. Alater specification called for the first ply ofroofing feh to be nailed directly to theinsulation before applying the hot appliedBUR to provide a more economical yetheat resistant system.

In the late 1950's a roofing productcalled ROOFMA TE . was introduced.

This was a foam fully wrapped in a heavyasphalt kraft laminate paper providing aroof insulation to which a BUR wasapplied directly without added protectionfrom the hot asphalt. This product wassuperceded in the early 60's by a boardextruded to shape with a polystyreneskin. The use of a captive blowing agentwas introduced a few years later utilizingthe same roofing system as the previousproduct. This concept utilized a dryapplied coated base sheet to provide thethemal barrier during construction. Theidea took advantage of the heat duringapplication to develop an intimate bondbetween the built-up roof and theSTYROFOAM brand insulation withoutcausing degradation. Alternate methodsof mop and flop, flying in or movable feltlayers were also used to apply the firstlayer of BUR.

STYROFOAM brand plastic foam wasmarketed as a base for a roof insulationfrom the 40's through the 60's. In 1950,the first protected membrane assemblywas installed using the STYROFOAMbrand insulation as the protection for theBUR. The system uses the inherent waterresistant properties, structural integrityand long-term insulation value ofSTYROFOAM brand insulation in adesigned way. The waterproofing, theBUR, was placed on the warm side, inthe position of the vapor barrier. Workcontinued into the early 60's when apatent was granted. This was foUowed bya number of developmental roofs usingvarious techniques and finishes whichwere evaluated until 1970 when thesystem was marketed as IRMA (InsulatedRoof Membrane Assembly).

The protected membrane assemblyconstructed using STYROFOAM RMbrand insulation is relatively new, but thebasic concept is not. Roof membranes,particularly BUR's, have been installeddirectly on flat structural decks for over100 years. Many of these had graveledsurfaces. Employing the protectedmembrane concept entails placingSTYROFOAM brand insulation on top ofthe BUR before the stone is applied. Theresult is protection for the membrane in apredictable manner from ultravioletradiation, mechanical damage, andthermal cycling.

The inverted concept gives per-formance regardless of the type ofwaterproofing material used-from thetypical 4-ply built-up roof to built-upmembranes with fewer plies; membranesusing coal tar pitch, low mek asphalt orhigh melt asphalt and with felts based on~

glass, asbestos, or paper. Also a numberof materials such as rubber, vinyl sheetmembranes, or certain liquid appliedmembranes can be used. Various finishesin addition to the stone ballast can beused to provide decorative or usefulfinishes. The key to the success is theinsulation material sandwiched betweenthe waterproof membrane and the finish.It must be resistant to degradationbecause it is subjected to all elements ofthe weather.

The protected membrane concept isfunctional for all market areas of roofing:new roofing, repair roofing andretrofitting (adding insulation to existingroof assemblies). In all cases, the owner isinterested in receiving and therefore thecontrartor is interested in deliveringeconomical systems that will perform fora long time. Today. more important thanever, this includes energy control alongwith water control. Not only must thesystem be watertight and requireminimum maintenance, it must controlthe flow of energy both in the summerand in the winter. This means the properamount and proper type of insulationmust be specified. In the protectedmembrane assembly. the materials workin harmony, i.e., the insulation protectsthe membrane and is independent of themembrane for its long-term performancecapabilities.

While the protected membraneassembly as used today is well-engineered, it does require a heavierthan normal stone finish, i.e., 10#/ft.2versus 4# /ft.2. Work is underwaydeveloping ways to reduce the total deadload to make the system more com-patible with existing structures and takeadvantage of the economy of lightweightdeck construction for new construction.

SUMMARY

STYROFOAM brand plastic foam has along history as a roof insulation. In theprotected membrane assembly itprovides a mechanism for providinglong-term performance. The proveninsulation value provides economicadvantages to the owner in this time ofenergy shortages and resultant highcosts. The proper amount of insulationcan be specified and enhance the per-formance of the roofing system. Theprotected membrane assembly utilizesaccepted and time-tried roofing systems,and is compatible with the new water-proofing membranes being introduced tothe market. It is made possible by theunique properties of an insulation such asSTYROFOAM brand insulation. . . *

by PaulE. Burgea, Jr.Senior Research Chemist

Jim Walter Research Corp

structural roof Insulation materialscurrently used. These commonly usedroof insulations are rigid polyurethanefoamboard. perlite board. fiberboard,glass fiberboard. foamglass, styrofoam.and composite boards. Comparativethenna\ efficiences of the basic types ofinsulation materials are shown in Fig. 1.

Over the past few decades. structuralsteel decks have become an IncreasinglyImportant factor in the roof constructionIndustry. Steel decks are unsuitable forthe direct application of BUR and,therefore. require a surfacing substratewhich generally consists of rigid in-sulation board. However, steel roof deckconstructions provide a unique conditionwherein high temperature developedwithin the structure. possibly as a result ofisolated local fire conditions, could causegases to be liberated from combustibles Inthe roof construction components andcould contribute to the spread of fire onthe underside of the deck. In order toqualify as Class I roof deck assemblies,

means of conserving energy by keepingthe heat In during cold weather and outduring hot weather. Since the roof area

COMPARATIVE THERMAL EFFICIENCY

URETHANEFCIAM(TEMPCHEK)

FIBROUS GLASS

PERLITE BOARD

FIBERBOARD

CELLULAR GLASS1" 2" 3"

thOck ,eqooit.d IOf .""...18"1THE~MAL RESISTANCE

fF11I (OF) CH~R. BTU

In these critical times of world-wideenergy shortages, dwindling and In-creasingly high cost energy sources, andIncreased urgency upon the conservationof energy, no segment of the con-struction Industry offers more Immediaterelief from this urgent sociologicalproblem than the Thermal InsulationIndustry.

Thermal Insulations are materialswhich offer resistance to or retard theflow of heat. An efficient thermal In-sulation material provides numerousobstructions to the flow of heat. Gen-erally, these obstructions consist ofvoids In Intermeshlng fibers, expanded orpopped non-conductive spheroids, orIndividual gas-containing cells in plasticor glass foams. These obstructing voidsor cells are sufficiently small that little orno convective heat transfer occurs and,therefore, insulating efficiency Is high.Roof insulation Is a type of thermal In-sulation designed for installation on theuPpenTlost surface of a structural unit as a

19

of single story buildings can represent85% of the total exposed area, a ther-mally efficient roof assembly can provideperpetual savings through reduced costsfor fuel energy necessary to provideenvironmental control for the structure.

There are seven major types of non-

ed for more specific thermal data.Composite roof Insulation is not

limited to steel-deck assembUes, butrather enjoys widespread use overnoncombustible structural decks such asconcrete, gypsum, asbestos-cement andother Class I struCtural decks such asimpregnated wood or cement fiber .Structural component composite in-sulation panels are also available and atleast one manufacturer offers a com-posite of perUte-urethane-perlite.

The current manufaCturers' literatureshould be consulted for definition ofspecific construction assemblies, andseveral approved construction designassemblies are described by FactoryMutual System and Underwriters lab-oratories, Inc., Guides and BuUetins.

...

ROOF INSULATION~

TABLE

C-VALUE COMPARISON CHART OF

COM PETITIVE COMPOSITE ROOF INSULATION PRODUCTS (1)

ThermalConductance,

C-Factor

CelotexTempchek

Plus.

GrefcoPermalite

PK ..

USMSuprathane

Class IApacheMillox

NAGComposite

JMFesco Foam

Panel EraInsul Roof I FURl

1715131211

1.25"1.5'1.6'

1.4"1.5"1.6"

1.2"1.8" 1.50" 1-1/2"

1-5/8"1-9/16'1-5/8"

1.4"

.109

.10

.0930908

1.6"1.9" 1.75" 1.75 1-3/4" 1.75' 2' 1-9/16'

1.8'1-11/16"1-13/16"2.0" 2-1/4"2.0' 2" 2.00' 2.0"

.07

.069

.061

.06

.OS

2.5" 2.5" 2.5' 2-1/2' 2.50" 2-1/2" .,.t

2.25'2.5"

2.8"3.2"

2.75"3.0"

2.75"3.0"

2-3/4"3"

2.75"3.00"

2-3/4"3-1/4"

2-1/4"2-1/2"

.049

.041

.04

.035

.031

. 02

3.0"3.5"

2-7/8"3-7/16'4.0"

4.5"

5-9/16"

(1) Values taken from published product literature. Nominal thickness includes facers.. Facer not included in nominal thickness

20

the heat release rates of the roofassembly must be within acceptable limitsdeveloped by FM to insure that thecomponents within the assembly will notcontribute directly to the initial spread offire under the steel deck. Specificminimum thicknesses of perlite, fiber-board, glass fiberboard, and cellular glasswere initially found to provide thethermal barrier qualities necessary toprovide this protectk>n. However, theneed for greater insulation efficiencywithout the added cost of multila~rconstruction and the design need forlower deadweight load factors gave birthto products known as composite.

The composites combine the excellentthermal efficiency of polyurethane foam(Figure 1) and the thermal barrierqualities of certain inorganic substrates.

Typically, the composite roof insulationboard consists of a specific bottomsubstrate thickness of perlite, mineralfiber, or glass fiberboard integrallylaminated to a core of polyurethane foamand a uniform top surface faced with anasphalt saturated roofing felt or fibrousglass mat for maximum strength andadhesion to the roofing membrane.

Composite roof insulation is generallyproduced in 3' x 4' or 4' x 4' panel sizesmanufactured on a continuouslamination boardstock facility. Productthickness range from 1-1/4 to 5-9/16".The published thermal conductancevalues (C-value) and correspondingthicknesses of several competitivecomposite roof insulation products aregiven in Table I. The product manu-facturers' literature should be consult-