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Observation From The Field: Fire Safety with Torch Base Sheets

Benchmark Service: Construction Phase Services

Issue: As the installation team neared the perimeter wall with the torch-applied base ply membrane, the Contractor aimed to extend the torch application to the wall surfaced with plywood. Additionally, the crew altered the direction of the membrane sheets during installation.

Solution: The Benchmark Field Consultant reminded the Contractor about the specified installation methods. To mitigate fire risks, torch-down sheets needed to stop 3 feet away from the perimeter walls. The final 3-foot section was to be finished with standard sanded base ply set in cold application adhesive. Hand-held welders and rollers were instructed for all seam laps within this area, instead of torch installation. Consistent direction for membrane sheet installation was required for the rest of the project.

Possible Impact: The Torch application must be carefully monitored to ensure proper technique and safety. Continuing with the current method up to the plywood area would have significantly increased the risk of fire damage to the facility. Altering the direction of the membrane sheet could have led to additional bridging potential at the points where the sheets intersect. Due to diligent project oversight, the contractor was prevented from deviating from the specifications, safeguarding the interests and assets of the building owner.

Cold applied sheet at plywood perimeter  
Proper installation of base ply membrane with cold adhesive at the plywood-faced perimeter wall.  


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