What is beam span tables? It is a table that helps you determine how far apart your posts should be and therefore the span of the beam should be. Before you buy anything, you should plan in advance by knowing the correct deck beam span to use. During the planning stage, don't forget to consider the spacing for your beams. You also should know the sze of the post you are considering to use, and
. that is where the table comes in. It will tell you what you need to know. The deck span is the distance a beam can span between supporting posts.