Fixing inconsistent milling on 5/4x6 Ipe tongue and groove

That is rough, Grant Ellison here. I’ve seen that exact issue with recent South American shipments where the milling tolerances are slipping. Frankly, that ‘industry standard’ line from the supplier is a cop-out for poor QC at the mill. If you are stuck with the material, skip the block plane and run a slot cutter on a trim router to open up the grooves slightly; it’s faster than hand-planing and more consistent. Moving to a square edge with the Mantis or Ipe Clip system is a smart pivot for the remainder of the deck to save your sanity. Just verify your joist spacing is tight before committing to the clip switch.

Derek Fontaine here. I dealt with this on a Hilton Head build last spring. Your supplier is dead wrong; that variance isn't standard, it’s a bad run. If you want to save the rest of the T&G, stop hand-planing and set up a custom jig with a power planer to shave the tongues uniformly before you lay them. Honestly though, making the switch to square-edge with the Mantis system is your best play for production speed. I’ve found that using a high-quality deck spacer and hidden fasteners on square-edge stock actually gives you a much cleaner look once the Ipe starts its natural seasonal movement.

Rachel Wood here. Man, I feel your pain on those Charleston humidity swings. If you're stuck finishing the T&G, quit the hand-planing and grab a dedicated tongue-and-groove side cutter on a router table. You can dial in your offset to hit every board exactly, and it's way safer than wrestling a power planer on site. That said, I switched to square-edge with TigerClaw clips for all my coastal Ipe work years ago; it handles the wood's expansion much better than a tight T&G joint that might cup or buckle in our heat. Save your back and swap the profile now.