b'How to Improve Installation Practices That Affect Single-Ply Performance "If you think thatvisible in an adhesive failure.) "Basically, theAlso, keep the tip of the probe horizontal with installation practicesweld is stronger than internal adhesion of thethe seam. Don\'t dig into the membrane, as this don\'t affect the long membrane itself. That\'s what we\'re looking tor."can cause significant damage and reduce the term performance of theExcessive Heat. Overheating theamount of thickness needed for protection, roofing system, thinkmembrane can result when either the airsuch as waterproofing. again," said Dwaynetemperature is too high or the welder speed isWalk Pads. When welding walk pads, care Wacenske of Firestonetoo low. "You want to avoid those situationsmust be taken to not overheat the membrane. Building Products.because excessive heating of the membrane"The thought is, \'Well, I\'ve got this thick walk Dwayne Wacenske"The roof may look fineduring the welding process can consumepad that\'s maybe 150 mils or thicker, so I need when you first leave thepolymer stabilizer, which is needed forto really crank up the heat to get that to weld,"\' job site, or even after a year or two, but laterlong-term stabilization." The ideal weldingWacenske said. "You don\'t need to crank up there can be some long-term issues stemmingcondition is the lowest temperature thatthe temperature or slow it down too much to from hot-air welding of seams," Wacenskeprovides a consistently good weld-meaningget good welds between the walkway pad and told attendees of the MRCA Annual Nationalthe scrim is exposed at production speeds,"the membrane. You probably can use the same Conference in Indianapolis. "We definitelyWacenske said. "We don\'t want to suggesttype of settings that you\'re using tor normal recognize that there are some localized high that contractors run the thing as slow asmembrane-to-membrane welds." To avoid heat issues that can cause failures in the field."possible; we want you to get production out ofproblems, do a test weld when setting up the He said that contractors can help orit. But, we want that temperature set as low asmachine. Also, give special care to darker areas, hinder the performance of the thermoplasticpossible so you get good welds."where there is an increase in temperature and membrane-whether PVC, TPO, or any otherWelder Drag. This is caused by theadded stress at the seam. roofing system that is heat welded-by takingimproper alignment of the hot-air nozzle on heMembrane Creases. To avoid tthe following simple steps:machine, and it can create gouges right outsideproblems, do not place weight directly on the Test Welds. Contractors should testthe seam, a weak area due to stress on thefold, but away from it. "Many times we fold welds at least twice a day-at the start of themembrane. "You have to watch that the machineover the membrane to . put adhesive down day, after lunch, and whenever the machineis set up properly and aligned properly so thisor put in fasteners," noted Wacenske. "There is is restarted. "The typical procedure is just todoesn\'t happen. Make sure that the edge of thea tendency to fo Id it over and kick it to get it to take some scrap material, weld it together,nozzle is as close as possible and parallel tocrease andold. That\'s not a good idea. Hard hand allow it to cool," Wacenske said. Rippingthe roller. If that nozzle is on an angle, we\'ll seecreases made during installation can lead to the seam apart too quickly can lead to falsedragging onsurface cracking years later." the edge." indicators, so wait for the seam to cool toProbing Seams. Often, probes end upDamage. "Damage to the membrane is check tor a proper weld and drag marks.sharp. "We\'re dragging that [probe] all daycaused by all the trades getting up on the root, Weld Failure. What\'s the differencelong, day after day, and it becomes very sharp.especially with PV and garden rooting going on," between a good weld and a bad one? LookYou can end up actually digging in and doingWacenske said. Protect the membrane by not for cohesive failure by pulling apart the seammore harm than good." To avoid problems,dragging equipment over it and by using cover until you see the scrim. (The scrim is notmake sure that probes are occasionally dulled.boards under generators and other equipment. MRCA News New Jobsite Safety ChecklistsSHARP Monthly Meetings and Available on www.mrca.orgToolbox Talks MRCA.\'s Health and Safety Committee has created checklists to help roof One of the primary benefits of MRCAembership is the assistance you mers stay safe on the job (visit www.mrca.org).receive to help stay compliant with OSHA, EPA, DOT, and other regulatory The \'Jobsite Safety Checklist," to be used by the person responsible fororganizations. Through the Safety andealthgendar Roofing ProfesH A foassessing a job site for safety, requires a signature and should remain on filesionals (SHARP) program, the safety manager on record receives safety for at least 1 year after coTnpleting the project. It\'s important that the persontraining materials foronth, as well formal training in the office each msigning the document reads each box and checks all applicable items.as Toolbox Talks foreekly presentations at the job site. Topics include wThe "Daily obsite Safety Reminder" helps ensure that a site is safehazardous communications, fall protection systems, ladders, scaffolding, JVisit the Memand meets minimum standards. The checklist is designed for a foremanfire extinguishers, emergency procedures, and much more. to use at the start of.-each day, when setting up a job, or as a referencebers Only section of the web site www.mrca.org for a complete list of topics guide if safety issues arise during the day.available and other safety related material. Please contact mrca@mrca. These forms are intended to help safety managers think about safetyorg to be included on the distribution list for these monthly materials or and the different components of a safe job site, prior to reaching the site.to provide suggestions on opicsou\'d like included in this program. t ySafetyTechnical&ResearchCommittee LegalAdvice9'