Posts and columns are the primary vertical supports of the deck. Problems here can affect the entire structure’s stability.
Table 4 in DCA6 provides the guidelines on 6 x 6 post heights based on the beam span, the joist span, and the wood species.
How a post and its beam are connected per DCA6 differs from the IRC requirements. Figure 8A shows the requirements.
Figure 8B shows additional methods that vary from what the local AHJ may approve.
Diagonal bracing is often essential for a deck’s lateral stability. DCA6’s Figure 10 details these components.