FastenMaster - Cortex Concealed Fastening System

Editor's Review: Hole Plugs for Composite Decking

Before the flood of hidden deck fasteners and specialty deck screws, I attached premium deck boards with screws and plugged the holes. The work was time-consuming and involved countersink drill bits and a pile of plugs, but the finished product was attractive. The Cortex system applies the same concept to synthetic decking, but it’s easier because the corrosion-resistant screws cut their own countersink hole when driven with a special square-drive bit that has a no-mar depth stop. The plugs have a reduced diameter on one end, so they are easy to drop into the holes, and unlike custom-cut wood plugs, they fit perfectly without any glue and align flush with the deck surface. I also don’t need to use a jig to keep fastener holes in line because once the plugs are set, you really can’t see them. For a flawless look, it’s worth taking the extra two seconds to match the grain on the face of the plug to the area surrounding the hole. Also, there are no racking concerns for those building in high-wind and seismic zones where clip-style hidden fasteners require additional diagonal blocking.

Cortex kits are currently available to match only Trex Accents, TimberTech TwinFinish, and Azek deck boards, but the manufacturer plans to expand its offerings. The system can be purchased as a 100-sq.-ft. or a 300-sq.-ft. kit, which includes the screws, the plugs, and the special square-drive bit. Using this system is slower than setting screws alone, but for a clean look and screwed-in security, Cortex is a great choice.

Editor Test Results: