Karen asks:
Triple wall is thick board and bunches/buckles in the corners. What is the industry standard for triple wall corrugated inside dimension?
Tolerances are usually given in the FBA Handbook. Beyond that are typically manufacturing considerations to understand in the converting of triplewall. As an additional resource, I recommend Guy Ockerlund.
—Ralph
From Guy – Typical mfg tolerance ranges for internal box dimensions are from +/- 1/4″ to 3/8″.
askralph 
November 27, 2015 at 3:21 pm
What you responded with was sizing tolerance. Karen’s actual question of scoring allowance deals with the expected inside loss of dimension from crease to crease which is a function of the board thickness bending around said crease.
Single wall board score allowance is usually half the thickness caliper of the board per 90 degree bend. The same goes with double wall corrugated board.
When dealing with triple wall corrugated board the outer most board layer tends to hold more towards the score. The inside loss leans more toward 75% – 85% of the total triple wall caliper thickness per bend. It will depend on which flutes constitute your 3 walls: BCA, ACC, etc.