Raising the roofto a new standard

Advanced polymers enhance roofing performance,

sustainability and economics

Pick a beautiful, clear, sunny day.Charter a plane and fly above anycity you like. You’ll witness animmense sea of blacktopped roofs

with an occasional beautiful white islandhere and there – these being testament tothe expanding preference for white as aroof finish. These “islands of change” havebeen surfacing for a number of years now.Their energy efficiency has become a solu-tion welcomed by commercial buildingproprietors and smart residential home-

owners. These white rooftops are mostlikely elastomeric roof coatings that arehelping to drive a better energy initiativeacross the United States and around theworld.

For example, California mandates “coolroofs” for all reconditioned commercialand industrial buildings. Cool Houston! isa program at the Houston AdvancedResearch Center designed to help reduceurban temperatures through use of cooltechnologies, including reflective roofing.Chicago is a major proponent of eco-friendly roofing. Tokyo is focusing onways to moderate the heat island effect.From the Lawrence Berkeley NationalLaboratory to the International Councilfor Local Environmental Initiatives,activity is underway to address the heatisland problem. Cool roof technology isa growing part of the solution.

A lasting solutionWhen specialty materials company Rohmand Haas set out to apply elastomeric coatings technology to roofing, they couldhave restricted their focus to meet only the

immediate need for durability. Instead, theyraised their sights – and raised the roof to a new standard of performance, durability,functionality and eco-friendliness.

The task was to develop materials that couldbe used in formulations that wouldmaintain and restore low-slope roofs over a variety of substrates under a broad range of conditions. The new polyurethane foamsystems, available for low-slope roofing,posed a difficult challenge of their own.They required a coating that would protectthem against UV light, but very fewsubstances will adhere to their surface.Research scientists at Rohm and Haas hadthe expertise to accomplish both goals. Theyalso had the experience to know that if theyapproached the problem in terms of improv-ing roofing systems, not just protectingthem, they could provide their customersand end users with even greater value.

Over the past three decades, the extent ofthat value has become increasingly clear.Elastomeric roof coatings, now recog-nized as key components of the buildingenvelope, enhance structural integrity,reduce maintenance, increase longevity,improve energy efficiency, and providesignificant, immediate and longer-termenvironmental benefits.

Strength in elasticityThe strength of elastomeric coatings lies in their elasticity, the property that enablesthem to expand and contract with the substrate, bridging and spanning smallcracks as the temperature fluctuates.Especially in temperate climates, a roof canundergo dramatic shifts in surface temper-ature, even within a single 24-hour period.Hot summers, cold winters, and the variable bridge seasons of spring andautumn (when daytime heating from thesun alternates with significant nighttimecooling) all contribute to mechanical stress.

Under these conditions, achieving just theright balance between tensile strength and elongation is no simple task. “That’s the trick,” says Rohm and Haas research scientist Vincent Bralic. “It’s got to be like a rubber-band. That’s critically important.And we know how to do it.”

To achieve that elasticity, elastomerics contain soft binders that behave like a liquid at room temperature. “But soft alsomeans sticky,” says Bralic. “The polymeritself is like flypaper. Dirt sticks to it.Rohm and Haas has unique chemistry in soft binders that gives them excellent resistance to dirt pickup. So, they retaintheir elasticity, but they also stay clean.”

2 RAISING THE ROOF TO A NEW STANDARD: ADVANCED POLYMERS ENHANCE ROOFING PERFORMANCE, SUSTAINABILITY AND ECONOMICS

Eight steps to a high-performance elastomeric roof coatingA coating that meets all your expectations for durability, energy efficiency, and asset protection is guaranteedwhen you can answer yes to each of these questions.• Will you be applying a top-quality 100 percent acrylic coating?• Does the coating meet or surpass technical norms such as the ASTM D-6083 specification (the American

Society for Testing and Materials’ Standard Specification for Liquid Applied Acrylic Coating Used in Roofing)?• Are the coating’s energy-saving properties certified by the Cool Roof Rating Council, or does it meet the

Energy Star program requirements?• Will the coating be applied in at least two passes, for a minimum total thickness of 20 thousandths

of an inch? • Will a roller, a brush, or a spray applicator be used and how will you make sure you obtain the right

thickness with either one of these tools?• If there are any leaks, will proper repairs have been completed before the application of the coating?• Has the proper surface cleaning and preparation for my type of roof been included as part of the bidding

process (e.g., spray-washing, removal of debris, priming, etc.)?• Should my coated roof be inspected and cleaned regularly as part of a preventive maintenance program?

White, clean and greenClean is a real challenge because the coat-ings are white. Why white? According toBralic, “If you have roof coatings, whychoose black? Asphalt is black because it hasto be. But anyone who has ever worked ona black roof knows how hot it gets. If youcould make it white, you’d certainly besmart to do it.”

That intuitive approach brings demon-strable benefits. Heat and sunlight degrade

roofing materials. Plus, excess heat on theroof adds to cooling costs throughout thebuilding. A 100 percent acrylic coatingprovides great resistance and protectionagainst UV light. Furthermore, if thatsame 100 percent acrylic coating is white,it will additionally provide solar reflectivityand emissivity. The result is a cool roof,lower air temperature and energy savings.

Cool and greatly improvedAffordable cooling is what first broughtwhite elastomeric roof coatings to the

attention of Liz Robinson, executive direc-tor of Philadelphia’s Energy CoordinatingAgency. In this city of brick and masonryhomes with flat black roofs, “excess heatevents” have been literally, and tragically,known as “killer heat waves” because manylow-income homeowners can’t afford airconditioning. Robinson’s agency saw afive-degree reduction in indoor, upstairstemperature from the use of the elastomer-ic coatings in combination with nighttimefans. Outside, the temperature of a roofsurface tends to fall by an average of fiftydegrees during a hot summer day.Robinson calls the reduction, “the perfectapproach for our housing stock and ourregion.” The summer cooling effect morethan offsets any heat gain by a black roofin winter by more than tenfold, accordingto Bralic.

Other advantages soon becameapparent as well. Robinson pointsout, “A lot of buildings fail becauseblack roofs fail. Elastomeric coatingschange all that and help preservehousing stock. They help change the home from a liability into an asset.” Robinson’s work includesblock-long projects in Philadelphia,

where all the buildingsreceived roof coatings.That’s resulted in addedcooling both indoors andout, because white roofsreduce the urban heatisland effect, unlike darkroofs and pavement thatabsorb heat, raising the

temperature in their vicinity.

New life for old roofsIn more ways than one, elastomericroof coatings are “green,” or envi-ronmentally advanced, if you will.Not only do they help provide ener-gy savings, but they also reducelandfill waste and provide substan-tial savings in maintenance andreplacement costs.

This is because over time, heat,sunlight and cracking due to

expansion and contraction degrade roofs.The traditional model was to tear off theaging roof and replace it after 15 or 20years. Elastomeric coatings can change allthat. “A coated roof could last the lifetimeof the building with regular maintenance,”says Rohm and Haas’s George Daisey,group leader, Elastomeric Roof Coatings – Paint and Coatings Materials.Maintenance is limited to occasional clean-ing with a hose or power washer and reap-plying the coating every 10 or 15 years.

Extending roof life indefinitely could have enormous impact. According to JeffChristian, manager of Oak Ridge NationalLaboratories Buildings Envelope ResearchCenter in Tennessee, a mere 5-year increasein roof service life should reduce the cost of

A “soft” wall of tough protectionThe benefits of elastomeric coatings are not limitedto roofs. Wall coatings formulated with this tough100 percent acrylic elastomeric material remain flexible but retain their tensile strength to protectover a wide range of temperatures. Their flexibilityand softness also provide excellent resistance todirt pickup and prevent wind-driven rain and moisture from seeping into cracks and causing structural damage, even in humid, hurricane-proneregions. Elastomeric wall coatings keep homes in one piece – safe and dry.

By bridging micro-cracks, elastomeric wall coatingshelp maintain masonry walls, protecting and renovating older buildings and providing integrityand maintainability for new construction. Recenttechnological advances by Rohm and Haas enablemodern elastomeric wall coatings to achieve newlevels of performance, appearance and functionality.

A superior solution to conventional paintsMicro-cracks make protecting masonry surfaces a special challenge. Conventional paints, includingmasonry paints, are based on “hard” polymers and form rigid films at ambient temperatures. As underlying cracks expand, the paint cracks alongwith them, violating the integrity of the coating.Protecting masonry requires a “soft” solution: coatings based on elastic polymers that can stretchacross the gap, bridging cracks and preventing water and salt from penetrating, and then “snapback” to their original state when the crack narrows.

ELASTOMERIC ROOF/WALL COATINGS 3

“With proper maintenance,a coated roof could last thelifetime of the building.”

©2008 Rohm and Haas. For more information, visit www.rooftopics.com.

roofing by 21 percent, saving the country$2.5 billion a year and cutting landfillwaste from roofing by 25 percent.Roofing waste currently representsalmost four percent of the total volumeof solid wastes in the United States.

Partnership assures performanceJoe Rokowski, a research scientist atRohm and Haas, notes that after 30 yearsof experience, “We know how roofs fail.

We have to know that so we can keepthem from failing. And that means work-ing closely with approved roof coatings

manufacturers who buy our resins.They’re the experts on formulation, manufacturing and real-world applica-tion conditions. That information is invaluable, and they have it.” Welltrained, certified contractors are also keyin assuring performance. “Someone who’sonly experience is painting houses can’tdo it,” says Rokowski. “It must be atrained applicator who knows whichcoating to use on a given substrate andhas the knowledge and skill to apply it

correctly.”

Forming collaborative workingrelationships with customers andcustomers’ customers is a corevalue at Rohm and Haas — onethat market manager Javier Banoscredits. “Close cooperation in thedevelopment of elastomeric coat-ings and their continuous improve-ment is what’s made the businesswhat it is today.”

Banos also cites his company’sactive participation in trade circles,adherence to rigorous standardssuch as ASTM specifications, theMiami-Dade County buildingcodes and California’s Title 24, andits role in initiatives such as EPA’sEnergy Star. “Roofs are complex

structures, and there’s a proliferation ofroofing substrates,” Banos points out.“These coatings must be able to adhereto all of these substrates and to performunder a variety of conditions, whetherthe roof is weathered or new andsmooth.” Collaborative partnershipshelp assure that they do.

Sustainable successElastomeric roof coatings are environ-mentally advanced and truly sustain-able, says Banos. “Not only becausethey reduce energy consumption andlandfill waste, but also because of what

they are: water-based and very, verylow in volatile organic compounds(VOCs).” Rokowski adds that that’smeant they’ve had to change very littlein the last 20 years, even to meetCalifornia’s stringent standards.

As good as today’s products are,Rokowski says, “We’re always trying to improve them. We were first in themarket, and we’re committed tomaintaining the lead, making sure ourcustomers have the best products outthere.”

Because customer and marketplaceneeds are constantly changing, Rohmand Haas is continually workingtoward new, best solutions. For exam-ple, coatings must be robust enough tocure despite dew or light rain in thehours after they are applied. Banos saysthat’s been mastered, and while “hardrain resistance is still a challenge, wethink we can solve it.”

Different regions pose different prob-lems. Rohm and Haas market managerIan Penboss says that in Asia-Pacificcities like Shanghai, high levels ofpollution make dirt resistance a majorbenefit, and in Tokyo, awareness of theheat island effect is focusing increasedattention on cool roof technology.

A winning combinationFrom skyscrapers in China to homes in America, elastomeric roof coatingtechnology is “a win-win for everybodywho uses it,” says Banos. “It’s a dualperformance product that maintainsroofs and makes them more energy efficient. The benefits converge whenyou consider the need to replace roofs.Then you’re looking at total economyand environmental sustainability overthe lifetime of the building. Thatmakes it even more compelling.”

Not just paint…House paint is typically about 4 mils (0.004 inches) thick, while elastomeric roof coatings cures to five times that thickness — 20mils (0.020 inches).