b'l\\lRCA Research Shows Roof Coatings Beneficial in Midwest Climates Continued from page 9 ~ closely examining and comparing the once coated membrane surface9.With respect to APP p m ified asphaltra ,appears olymerod memb nes it with the uncoated, exposed and weathered surface of the controlthat all of the c ings, particularlyacrylics and the em ons, areas.oat theulsi are 2.Most all coatings in v climactic areas test roofs are well adhered,performing better over the more stable, fiberglass-surfacerein ed, ariousforcand in general are performing quite well. Inr,in the areacommercial-grade APP modified m b nes. So far, with respect to the othe words evenem ratherced APP with the most severe temperature and weather extremes,Minneapo polyester, mid-reinfo ,modified membranes and the multiplelis/St. Paul area of Minnesota, the coatings are well bonded (e.g., notreinforced APP membranehm near the top surface of the wit fiberglassat peeling), and in all but atest areas, the coatings a layingsh ), the other coatings\'performan is not discernably different few coatedreeet(s ce smooth and continuous (e.g., not stress cracked or crazed). (See Photofrom either of the two types of APP modified asphalt membranes. No. 1.)10.The following coatings are performing very well, and incircumsome 3.T black asphalt emulsion primed areas, which wereexposed asstances extremely welparticularly over thehalt emulsionimed heleftI,asp prprimed control areas, are showing some signs of cracking and erosion.areas (See P 5): hoto This cracking is most pronounced where the lackglazing craftsman 1. Premium-grade aluminum-pigmentedsolvent-based asphalt coatof ship during membrane application allowed the hot asphaltcoat toings glaze be applied too heavily, thereby promoting alligatoring of the glaze or2. SBS polymer modified, aluminum-pigmented solvent-based asphalt "flood" coat of h asphalt and the emulsion coating.coating ot 4.Most all coatings are notsigns of significant changes in hue or3. White acr coating showingylic color. During the first year of the stu itthat the commodity 11.As anew c egory of coating,SEBS andSBS polymer dyappearedrelativelyat thethe white,somebitified,asphalt roof grade acrylic coating was as bright aand inlocations amod solvent-based,coatings are performing extremely brighter, than the premium-grade acrylic coating. However, this pastwell. However, in some locations, the SEBS modified coating is dulling year\'s weather exposure has proventget what you pay for," asa,iflight oils are migrating andningsurface, thereby tha "youbit asthestai the the commodity-grade acrylic coating no longer has thewhite huech thehue of the coated areas. As of a r nt visit to the brightangingsurfaceecethat the premium-grade acrylic coating shows.Minn site,theSBS modified coatings appear to be performing esota 5.Also during the first year of theit appeared that the commodity extremely well, at least judging by the coating\'s appearance with the study grade,solvent-based,aluminu asphaltcoatingwasasnaked eye andr slight magnification. There is no visible interrup-m-pigmentedundebright and as visually reflective as the premium-grade, solvent-based,tion in film continuity,or micro-cr king, noof~ no crazingac signsero-aluminum-pigmented asphaltHowever, thisyear\'s weathersion,in general,SBS modified asphalt,um pigmented11l coating.pastandthealuminexposure has p that qu is important, as the commodity-gradecoating looks very promising for long-term performance. rovenality aluminum-pigmented asphalt coating no longerbright hue that has the the p ium-grade aluminum-pigmented asphaltdisplays.Conclusion rem coating 6.Stress c and splitting through the emulsions and aluminum-pig M trusts that this preliminary data sh some ght on the weathering racksRCAedslimented coatings, directly over the end laps of the polyester reinforcedprotection and performance benefits that are available toroofingry theindustSBS and commodity-grade APP polymer modified asphalt membranes,through theof various roof coatin inroof application well as usegs,news, as indicate that these membranes are undergoing post application shrink for use inmaintenance situations. Judging from these in ial fin it roofit dings, age. However, at test areas where white acrylicwereappears th certainings, when applied overlect membranes, h the coatingsappliedatcoat se ave over the same polyester reinforcedmembranes,no stress cracksorpotential of significantly extending the service lifethe alr ll sucofeady overashrinkage were observed in the coating over the end laps of the mem cessful performance of multi-ply asphalt-based roofm nes. me brabranes. This finding provides reason to believe that the white acrylics therebytheetterrify are moderating the thermal movement of the membrane,keep MRCA expects to perform laboratory work infuture, to b cla the ing these p r r sheets from shrinking. (See Photos No. 2performance and benefits that roof coatings may be providing to the asphaltolyeste einforced and 3.)based roof membranes involved instudy. The testing is in to help thetended 7.In regards to adhesion of the acrylic coatings, the bond and the peelidentify other potential benefits that the coatings may provide - such as strengths of the acrylic coatings was increased at the locations wheremaintaining fire resistance, solar r n,other we shielding propeflectio andather the smooth-surfaced asphalt-based membranes had been primed wither that may promote membraneity throu proper roof maintetieslongev gh asphalt emulsion. (See Photo 4.)nance - for those working indiverse climates ofMidwest. thethe buffer to 8.The asphalt emulsion primer appears to be acting as aminimize the bleed through of light oils over the glazed BURs and commod Acknowledgements ity-grade APP modified asphalt membranes. Where primer was not usedMRCA\'s T&R Committee wishes to extend sincere gr u toeciatit deth partiover these same membranes, the light oils of the asphalt bled throughpating manuf urers and contractors whove donated coun hours aact ha tlessnd some of the coatings.the areas where the membranes were prim effort to this project. T writers wish toratulate all of the projects\'Inedhesecong parwith asphalt emulsion, it appears that the emulsion has served as aticipants for their efforts to better the roofing industry. buffer and the asphalt\'s oils are not staining or degrading theof the hue coating.'