BEAM SPANS RB190—This proposal makes beam design for decks much more flexible. The current table in the IRC for sizing beams is based on the span of the joist supported by the beam, but it assumes those joists are at their maximum allow- able cantilever beyond the beam. For decks with flush beams and no cantilevered joists, the maxi- mum beam span is incredibly
conservative. NADRA proposed a footnote modification method that will allow the table to be more flexible and alter the values based on the lesser amount of cantilever. The example used in the proposal showed how a beam without cantilevered joists was still being limited to a maximum 7 foot 4 inches, but with the new footnote modification would actu- ally be able to span 9 feet. The committee agreed that this was a much-needed flexibility to the table and approved the proposal.
JOIST SPACING RB 191—This is a proposal that deck builders may not be thrilled about. The maximum joist spacing of different thick- nesses of wood decking assumes each board is spanning at least two joist bays, bearing on three joists. The code change maintains the maximum joists spacing for decking supported on at least three joists, but reduces the maximum spacing for decking supported by only two joists. For these short lengths, the maximum joist spacing will be approximately half.
To learn more about deck code updates and the evolving state of the deck-building industry, visit NADRA.org.
Whereas a beam without cantilevered joists was being limited to a maximum 7 ft. 4 in. span, the new code modification allows it to span 9 feet if the joists terminate flush with the beam.