These accent deck boards that are installed flat on decking structures provide for moisture to be trapped under the deck boards. This trapped moisture will cause the deck boards to cup as the face of the deck boards dry – the edges turn up. Several joists together provide this type of flat surface under border boards and wrapping the visible perimeter joists do too. To prevent this, you can kerf (groove) the bottoms of the deck boards with a skill or table saw before installing the boards. The cuts should be made from end to end on bottom or back of each board 1 to 1 1/2 inches apart and a depth that is 1/2 the thickness of the board. This will prevent cupping.
https://www.bwdepot.com/wp-content/uploads/2019/06/BWD-Blog.jpg 400 600 m16Dev https://www.bwdepot.com/wp-content/uploads/2019/05/BWD-Logo.png m16Dev2009-11-29 17:31:342019-06-12 18:04:04Install Fascia, Trim, Border and Wrap Deck Boards To Prevent Cupping or Warping