The invention concerns a capping board assembly and its multiple connectable sections. Each pair of sections is connected with an interlocking joint, each of which comprises at least one projection and at least one recess that cooperate and prevent the longitudinal and lateral movement of the sections. Each interlocking joint is reinforced by a rod embedded within the section and extending within the projection. The rod has a tip that anchors the projection. The interlocking joints allow precision assembly of the sections of the capping board which greatly benefits strength, installation, replacement and transportation.