I have an older Kayak pool which I rebuilt and refinished two years ago. One of the problems I found was the wood 2x4s that support the decking and hold the coping strips in place (which holds the liner up). The old 2x4's were rotten so I obtained new 2x4's and cut the 1/2" grove in them so they would sit on top of the wood walls as was originally done. This worked well for two years. The problem is those 2x4's are now splitting.

Contacted Kayak pools to see if they had a new product to replace those 2x4's. No they didn't... They did have new aluminum metal framework but that means a new liner and throwing out the coping strips that I replaced two years ago. And also means replacing the metal framework.

So are there better 2x4's that won't split? Or is there some other replacement for the 2x4's?