Although I’ve built  many decks for clients using cedar, and more recently Trex, I’ve never used one of the tropical hardwoods.  This spring I’m going to rebuild my own deck so it seemed like a good time to give hardwoods a try.   Ipe is our first choice but the Cumaru is also attractive to us.  One of the potential suppliers is requiring that I sign a waiver stating that I understand that if I use the grooved Cumaru there may be issues of the wood warping to the point it could pop out of the hidden fasteners.  I haven’t seen any other references to Cumaru having this type of an issue.  If anyone has experience, good or bad, with Cumaru I’d appreciate their feed back.