Use of clear span for length of wood members

I suggest offering the ability for wood members to be designed with “clear span length” in inches rather than “beam plan length” in feet. (That’s two separate recommendations in one sentence.)

The clear span length is more readily known in wood framed construction where we are working with a wall-to-wall dimension, or width of a door opening, or distance between a foundation wall and a second support point. The “beam plan length” is more appropriate for steel construction where we use work points and column/spacing grids for member sizing.

For example, an engineer sizing a single 3’ door opening might enter a beam plan length of ±41" (entered as 3.41667’) to account for door+rough opening+half width of bearings. It would be cleaner and more accurate if the input could simply be 38" (R.O. = 1" each side) for the clear span and let the program add half of the bearing width to each end of the span, for example.

This is also more consistent with other programs and IRC nomenclature (See figure R802.5.1 for example for rafters). I can’t find a definition in the IRC for floor framing, but a typical web search shows clear span as being accurate.

Thanks a lot for your feedback! We really appreciate the explanation from an experienced engineer such as yourself. I have flagged this and notified our engineers. Thanks again!

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