The I-joist Calculator computes the number of i-joists are required for a floor based on the dimension of the room. The user can also enter the on-center separation of joists, but the system has 16" on-center separation as the default.
INSTRUCTIONS: Choose your preferred units and enter the following:
I-Joists Count (iJC): The calculator returns the number of I-joists needed for the floor.
This algorithm makes no assumptions for the maximum span. It is assumed that joist of the appropriate span can be found (steel, I-joists, or other materials). This equations only provides the number of the spanning joists (brown-red in diagram) and not those on the very edges (e.g. first and last plates). See diagram. It does assume that the first and last i-joist are right next to the edge plates.