The wide sealing washers eliminate leaks in the expanding and contracting polycarbonate and the wide surface area of the washer provides a strong hold, keeping the polycarbonate from being sucked out in strong winds . These screws should never be used in wood frames. The screws are also not to be used to drill holes in the Trim, this should be done with a standard metal drill bit. At Cap and Corner Trim the wide neoprene washer provides an excellent seal and the extra spring action helps to keep the Trim Component tight against the polycarbonate, creating a watertight seal. Order sufficient quantity, or a little extra.
Small shipments are costly.
Polycarbonate Technical Info Sheet Selection Sq. For framing layout see Typical Layout for Multi-Wall Polycarbonate Over Wood Frame . Sheet thickness affects framing requirements. Also, -Fire Test Report if need. Dept. may request some of the above.