Base-Sheet-Fastener-7-Inch.pdf

This is a technical drawing specification document for the Middle School Roof Replacement project in Michigan, detailing base sheet fastener placement requirements for built-up roofing installation on lightweight concrete decking. The specification mandates attachment of Tremco-specified base sheets to roof decking using approved fasteners and discs, with fasteners spaced 7 inches on center along sidelaps and in two staggered rows down the longitudinal center of each sheet, positioned 12 inches from each edge. The document establishes increased fastening requirements at perimeter edges (70% increase) and corners (160% increase) in accordance with FM Global Loss Prevention Data Sheets 1-28 and 1-29, with a minimum spacing of 4 inches on center between fasteners.

The drawing (DWG NO. 15) is presented at a not-to-scale (NTS) representation and includes dimensional callouts showing the 4-inch base sheet width margin and the 7-inch on-center spacing intervals. The specification emphasizes flexibility in fastener density calculations on a unit area basis, allowing contractors to add additional rows and increase fasteners per row as needed to meet wind uplift and structural requirements while maintaining the 4-inch minimum spacing constraint. This technical guidance serves as a binding specification for contractors bidding on or executing the roof replacement work.