CoatingsPro Magazine

MAR 2017

CoatingsPro offers an in-depth look at coatings based on case studies, successful business operation, new products, industry news, and the safe and profitable use of coatings and equipment.

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COATINGSPRO MARCH 2017 67 coating, there appeared to be many random areas of corrosion that were not associated w ith visible coating damage. Additionally, there were panels that would be most likely to display damage, due to the common installation patterns, if the mechan- ical damage was solely to blame. T hese areas did not reveal any coating damage or corrosion. Finally, the extent of the corrosion, w ith holes through the decking after only five years in ser vice, indicated that there may have been additional problems w ith the decking or w ith the architec- tural design of the building. Representatives of the roofing material, coating material, and the maintenance staff were all present to review the roof at different inter vals and then brought together to discuss the issue. T he roofing materials repre- sentative asserted that the coating material must be too soft for use if that much damage could occur during installation. T his assertion caused the coating manufacturer to include the applicator of the paint and the supplier of the metal substrate in the now vocal negotiations. Additionally, it was proposed that the damage may have been caused by the building mainte- nance staff using shovels on the roof surface during a snow event. ings became tense, and there was not going to be an easy solution or a quick resolution. e representa- tive of the roofing material indicated that they were not willing to pay for the repair. At this point, the build- ing owner contacted an expert in the roofing industry to get an indepen- dent evaluation. Investigation Findings e expert arrived on site and walked the roof with a critical but independent view. ere were some areas where it appeared that mechanical damage was indeed the starting point for the corro- sion and the subsequent water entry into the building. However, he was concerned with the extent of corrosion that had developed over the relatively short time period and wondered if water had entered the building in other areas and the corrosion was being exacerbated by conditions on both sides of the roofing material. T he coating was specified to be applied over a galvanized surface, which theoretically should slow the progress of the corrosion if a coating defect occurred. T he roofing expert asked for samples of the roof deck to be removed from several areas, repre- senting different levels of corrosion for further investigation. T he first items evaluated were the adhesion of the coating material to the galvanized surface and the dr y film thickness of the coating. T he adhesion away from the corroded areas was rated as good to excellent when using a cross-hatch adhesion test. T he Magnified at 30x, the area outside of the corrosion "spot" showed to have low zinc, which should have been present as a protective layer. The coating was specified to be applied over a galvanized surface, which theoretically should slow the progress of the corrosion if a coating defect occurred. Holey Roof Decking

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