The floor joist span tables incorporate vibration criteria. The tables recognize that some floor constructions are more “bouncy” or “springy” than others. Therefore, by adding blocking or increasing subfloor thickness, floors will be less springy or bouncy and floor joist spans may be increased. Alternatively, engineered wood products such as laminated veneer lumber joists, wood I-joists and parallel-chord trusses may be used, but vibration criteria must be also be considered for these engineered products.
Source : Canada Mortgage and Housing Corporation (CMHC)