b'SHOCKS- ThermalAndOtherwise Await MidwestConventioneers( HEN YOU tie sheet metal to built talent,theleadersofthediscussionses by suddenly moving skywards. You will be W sions will befaced with one of themosttoldhowandwhyit happened,andwhy up roofing, what happens when both are subjected to varying degrees of expan articulate audience groups in the buildingit should not happen. sionandcontractioninresponsetotem industry,and-whilethepanelistswill,asSession leaders include Bob Marquis of perature change?usual, provide some fireworks,the displayKansasCity,MiltOlsonofOmaha,NeAnd what happensif the movement iswill be equalled only by thepyrotechnicsbraska,Bob KoderofDesMoines,Iowa accelerated by a rapid, precipitous drop inof the explosive audience.( theconventionhostandMRCApresitemperature?TheseandotherproblemsWhilestructural movement and designdent),CottonPowersofLincoln,Newill be discussed, probed and analyzed atproblems is the central theme of the con braska, and Tom Manson of Kansas City. the13th Annual Convention of the Mid vention,therewillbeanexpertanalysisTheconventionwillbe punctuated by west Roofing Contractors Association, No ofcoldprocessroofinginvolvingasphaltentertainment, with a special program for vember 8th to 10th.emulsionsandcutbacks,neoprene,Hypa theladies-andthere\'sahundred tickets lon, Bitumagic, TNA200,Monoform andfortheIowaState-Oklahomafootball The convention is located at the Hotelother old as well as new entrants into thegame in Ames, Iowa, on Saturday, NovemFort Des Moines, Des Moines, Iowa, whichfield of "cold-stuff."ber10th.(Ticketsareonafirstcome has had its exhibitarea taxed to capacityAlsoontheprogramisaseminaronbasis.) by a record number of exhibits of roofingtheuse andabuseofequipment. DoyouAnd there\'s a cocktail party, a banquet materials and equipment.rememberreadingaboutacylinderofand dance on the final day. While there is a galaxy of forum panelPropane fuel, that emulated a space vehicle MinnesotaContractorscurbs,contractionJoints,lightningrods,onitsemphasisonthedamagedoneto Issue11 Roofers\'conduit, etc. and a list of all pitch pockets.bituminousroofcoveringsbysudden 8. If other trades use the roof for work drops in temperature. Recom mendations 11ing and traffic, a temporary roof should beWhatoccursontheroofissimilar to applied and thefinish roof placed over itwhat happens when the driver of a car or Atthe1962N. R. C. A.Conventionwhentheothertradeshavecompletedtruck pours cold water over an overheated Roy Dose met head on a series of techni their work.engineblock.Thesuddendropintemcalquestionswithsomeofthesaltiest9. Allstandingwateronroofsbeing perature causes the block to crack, whereanswers delivered at a convention.repairedshouldbepumpedoff,andtheas the same temperature drop with a gradThisistypicalofMinnesotawhereaold roof dried before reroofing.ualreductioncouldbeabsorbedwithout spade is not called an agricultural instru 10. Roofingcontractors\'guarantees damage to the block. ment,andwhereRoyandhisassociatesshouldbetwoyearsfromdateofcom N.R.C.A. believes that repeated thermal haverecentlytalkedturkeytoarchitectspletion.shocks arethecauseofmostroofcracks, andgeneralcontractorsinaseriesof11. Roofing,inallcasesshouldbebucklesorwrinkles.Mostresearchers Roofers\'Recommendationsthathaveappliedoveraroofinsulationboard,ex agreewiththethermalshocktheoryas raised eyebrows in Washington as well asceptwherenot necessary onwooddecks,regards roof cracksbutthereisnounaMinnesota.andtheinsulationshouldbeappliedmnimity of opinion. These are the recommendations:two layers. 1. Roofdecksshouldhaveexpansion 12. Roof decks should bedesigned tojoints at 100 foot intervals in both direc carry a50lbs. per sq. ft. live load. tions.The Minnesota list of recommendations 2. Norooflengthshouldexceed3 concludewiththefollowingassociation times its width without contraction jointsstatement: and at "L\'s," "E\'s," wings, and adjacent to"We realize that this is a drastic stand pent-houses near the center or side of theto make and yet as of today no one else long length.hasbeenwillingtoabsolveusofthe 3. Themaximumlengthofabonded obligationsforcedonus,nordemanded roof should not exceed7feet. 5thatcertainpracticesbechangedthat 4. Roof plans must not be drawn to a would improve the roofing industry." scale smaller thanI/16th to the foot. 5. The roofing contractor must be notified of any change in the roof plan.N.R.C.A. Tackles 6. All roof plans should show all pent ThermalShock houses,ventilators,airconditioners,sky lightdomesorocherprotrusionssotheThephrase"ThermalShock"was first roofing contractor can make provision forintroduced to the roofing industry by the them.AmericanRoofer&BuildingImprove7. The plan must show the exact loca mentContractor.Wecongratulatethe tionofallroofopenings,stacks,drains,National Roofing Contractors\' Association NOVEMBER,196219'