Supporting the ends of composite decking boards is important for several reasons.

Firstly, composite decking boards can expand and contract with changes in temperature and humidity. This movement can be more pronounced at the ends of the boards. If the ends are not properly supported, they can sag or even break, causing an uneven and unstable surface.

Secondly, composite decking boards are typically heavier than traditional wood boards. This extra weight can put additional stress on the ends of the boards, making them more susceptible to damage if not properly supported.

Finally, supporting the ends of composite decking boards helps to ensure a more uniform and attractive appearance. Without proper support, the ends of the boards may bow or warp, leading to an unsightly and unprofessional finish.