Benchmark Service: Construction Phase Services
Task: Benchmark was asked to conduct a final Inspection on a 92,000-square-foot retail store where a roofing contractor had proposed a restoration coating of an existing single-ply membrane roof system. Benchmark was engaged to conduct only a final inspection of the completed installation.
The project involved applying a reinforced coating over an existing mechanically attached thermoplastic single-ply membrane. The contractor, who was also the coating manufacturer, provided the client with a one-page, 12-line-item scope of work.
The entire roof was to receive three coats of the elastomeric coating, with reinforcing mesh embedded between the first two coats. Additional coating and reinforcement were to be installed at the perimeter and penetration laps/seams as well as in the drain areas. The final topcoat was to be white.
Findings:
Upon accessing the main level of the roof, it became clear that the topcoat application was inadequate. The gray base coat was visible through the topcoat. Closer examination of the field membrane revealed numerous deficiencies, including loose coating, splitting, “mud cracking”, and debris coated into the roof system.
The inspection of the mechanical penthouse roof revealed even more significant deficiencies. Topcoat application was inadequate, similar to the main store level. In addition, the topcoat stopped short of walls and penetrations in several locations. None of the perimeter membrane seams were three-coursed with coating and mesh, as specified in the scope of work. Splitting was observed on the top of one wall and was not repaired. The most troubling deficiency was the lack of any topcoat on all of the perimeter walls and many of the penetration flashings.
Recommendations: The contractor failed to follow its own proposed scope of work. Corrective measures were specified for all defects, including power washing and recoating the entire facility. The client and Benchmark agreed that a follow-up inspection was warranted.