I recently installed a composite deck with the deck boards produced by Care Free. The deck boards are standard 2x4 but have crevasse in the middle. Anyway, the local Home Depot explained that all I needed to due was have 24” on center joists and use their hidden brackets. I actually installed my joists 16” on center, since I was laying my deck boards diagonal. After installing the deck boards, my wife and I are extremely disappointed. The boards have a give to them and tend to bend in between the joists. I went to another Home Depot last night and talked with a guy that was much more knowledgeable, and he explained that his is a common complaint. He recommended installing ¾” angle iron within the crevasse of the deck board. This seams extremely expensive, since I’ve already invested over $3,500 in the deck. So, I was wondering if I could cut 3.5” strips of CDX plywood and lay in the crevasse, or lay full sheets of CDX plywood then attach the composite decking on top of that. Another issue that I’m worried about is the CDX rotting after a few years due to rain and snow. What are your recommendations??