Should the back panel be 5mm or 9mm?

How to choose between 5mm and 9mm depends mainly on the installation method and budget. 5mm back panels are mostly grooved-in, with low cost and a lighter cabinet body, suitable for standard wardrobes; 9mm back panels offer better strength, can be nailed in place, and provide more reliable moisture resistance, giving more peace of mind for kitchen cabinets, tatami, or walls adjacent to bathrooms. For edge banding we can use PUR edge banding or laser edge banding; proper treatment of back panel edges reduces moisture-induced deformation. At the factory you can observe the cutting, edge banding, and side-hole processes. The specific thickness should be decided according to the cabinet body's use and wall conditions, not applied uniformly.