What door thickness should I choose: 35 mm, 40 mm or 45 mm?

Thickness drives both feel and performance. 35–38 mm suits light residential use and keeps hardware costs down. 40–45 mm is our standard for main rooms: it improves sound reduction, gives a more solid close, and accepts heavier locks and concealed hinges. For tall doors over 2.4 m or acoustic applications, 45 mm with a dense core is the safer specification.