b'betweenroofingandbasedueto hygrothermal movement; the action of lowpressureduetowindwhenthe roofingissecuredandunprotected," along with other mechanical behavior of this method of roofing. H.HECHLER,BRAASANDCO., FederalRepublicofGermany,presented a very comprehensive paper on severalsystemsofflatroofwaterproofing. The wage situation in almost all European countries makes prefabrication imperative, thus he said, in theIi Federal Republic of West Germany anL-R:William Steinmetz, Past President NRCA; Ed Mertz, NRCA Technical Director; Mrs. Willy Manderveld,Willy Manderveld, Secretary General, International Association of increase in the use of plastic roofing isRoofforecastand astepinthatdirectioning Contractors, Brussels; Charles Raymond, NRCA President; Marshall Roy/lfanchester, England; and Denys J.C. Lingard, National Aswciation British Roofing alreadytakenintheuseof"PlasticFelt Manufacturing Roofing Sheets loosely laid,simply on top of one another without a binder andmethods wereequauy et!ective,eachroof. Their study included a number of held in place with a surface of gravel orwith its own advantages and disadvan formulas to establish temperature flucacourseofroofingslabstopreventtages.tuations under varying conditions and stripping by highwinds."Sprayed roofs require more compli structures. Thissystemcalled"Trocal"wascatedequipmentandanautomated developedby Dynamit NobelAG,ofsprinkling system, which often resultsA SELF-ADHESIVE BITUMINOUS Troisdorf, Western Germany andhasinan excessive useof water, duetoROOFINGSYSTEM called"Gumlon" been used successfully in Europe sinceevaporationinhighwindareas,andwasdescribedbyK.Yamamoto, 1966. The system was introduced in thetemperaturefluctuationsarehigherTajima Roofing Co., Japan, followed by U.S. recently through Dynamit Nobelwithasprayedroof,coorespondinga movie showing the application steps. of America, a wholly owned subsidiarywiththeswitching on andoffof theGumlonisapressure-sensitive,selfwith headquarters in Northvale,N.J.sprinklingdevice,thushavinganadhesive sheet which upon removal of The Trocal system,theysaid,nowadverse effect on the roof.Dry areasits release paper can be bonded tightly covers more than200millionsquareoften form during windy days resultingto anotherGumlon. Sheetwhichhas feet on European roofs,including thein a local thermal stress in the felt andbeen adhered to the deck with a layer Olympic Village in Munich, which alonegravel roof.of rubberised bitumen. It is provided in involved nearly one million square feet.Water-filledroofs,too,canbeafour grades depending on the end use At present about 15% of all flat roofshazard,theyconcluded.Notonlyisof the product. builtinWestGermanyarebeingthere the danger of a roof overload, butMr.Yamamotopointedoutthat covered with Trocal.the reservoir of water can accumulatethere is a great difference between the APAPERON"EffectiveTypesofdust and sand, forming asilt crust onconventionalbuilt-uproofingsystem Roofs Designed For Hot Climate Con thebottomofthereservoirwithandthe GumlonSystem,nor doesit ditions" was the result of the combinedbiologicalprocessesstartinginthehave any relationship to the so-called effortsofS.I.Permiakov,B.S.water.\'singlelayerroofingsystem\'.The Mezhevnikov, andVentilated roofs are the most simpleadvantage of Gumlon, he said,is that Y.A. Tabunshchikov, whodescribedfieldsurveysonhowtouse,theysaid,but theyarelesseven if the application work is poor, it best to protect roofing in hot climateeffectiveincontrollingoverheating.willhavelittleeffectonthe areas such as foundinCentralAsia.The search for a roof cooling systemperformance of the system. Water-cooledandventilatedroofswas deemed of importance due totheIF ALL ELSE FAILS, say proponare the most effective in terms of theirintensesolarradiationinthehotents of roofing tile, let us return to the heat protecting properties in summer,regions, with buildings with large roof"goodolddays"whentilewasused theysaid.Ofthe water-cooledtypesareasbecomingexpensivetoairalmostexclusively.Thesuccessof they tested two different methods, (a)conditionorcool,especiallyinthese roofing systems can be proved by Water sprinkled roofs,and(b)waterstructureswithoutwindowopeningsthe slate and tile roofs in England over filled roofs. Inthey found that bothwhere a large heat input is due to theContinued on page 18 use, L- R: J. Gudas, ABC Editor, George Stephenson, NRCA-MRCA; KeithMathay (U.S. Bureau oftandards) and Dr. SPearson,D. Anderson &Sons, Manchester; Brian Tudor, Roy Roofing,Yoshima (Japan)participatein a joint disLeeds; and Anders Buchwald, Akts JensVilladsens Fabriker, Herley,cussion in one of the seminar programs. Denmark,manufacturers of the lcopal roofing system described in a recent issue of ABC. ABC, OCT. 19747'