Floor girder and post spacing — the same table a header uses, not a wall opening

Posts set the girder’s span — the same IRC R602.7 table a header uses, sized via R502.5. Every post needs a positive connection to the girder (R502.9), not just gravity bearing, and its own footing. With 3+ posts, each bay is an independent simple span.

An elevation of an interior floor girder carried on three posts down to their own footings, with floor joists bearing on top of the girder (a drop beam) from both sides. The distance between posts is the beam span, dimensioned and labeled post spacing, capped by the achievable span from the IRC girder table. A callout notes every post-to-girder joint needs a positive connection, not just gravity bearing, and each post has its own separately-sized footing. A second callout notes that with three or more posts, each bay is sized as an independent simple span — the prescriptive table gives no credit for a continuous beam. — Source: IRC R502.5 / Table R602.7(1)-(2) (girder spans); R502.6 (bearing); R502.9 (connection)

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An elevation of an interior floor girder carried on three posts down to their own footings, with floor joists bearing on top of the girder (a drop beam) from both sides. The distance between posts is the beam span, dimensioned and labeled post spacing, capped by the achievable span from the IRC girder table. A callout notes every post-to-girder joint needs a positive connection, not just gravity bearing, and each post has its own separately-sized footing. A second callout notes that with three or more posts, each bay is sized as an independent simple span — the prescriptive table gives no credit for a continuous beam.

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