Close the Miter Joint

What happens here

With the mitered boards in place and the small gap, the boards are then forcibly pushed together. The slight flexibility of the composite decking material allows for this compression. As they are pushed, the gap between the mitered edges closes completely, forming a very tight, seamless, and visually appealing corner joint. This technique creates a perfectly flush surface without any visible gaps at the corner.

Goal: Achieve a perfectly tight and seamless mitered corner joint.