The National Building Code of Canada 1990 specifies the allowable spans for lumber floor joists that are expected to lead to satisfactory vibrational behaviour. This paper discusses construction methods that improve the floor behaviour once the flooring and joists appropriate to a particular building occupancy have been selected. Laboratory tests on full-size floors demonstrate that adding between-joists bridging and supporting all four floor edges significantly improves the overall vibrational performance of wood floors. Bridging consisting of solid blocking glued to the underside of the flooring and a mild steel strap nailed to the underside of blocking and joists is more effective than several alternative details. Incorporating pads of damping material between flooring and joists, or at bearings, can have a detrimental effect on floor performance. The use of elastomeric adhesive, in lieu of nailed flooring-to-joist connections, does not significantly enhance the mechanical performance of floors with lumber joists. Key words: lumber, vibration, serviceability, floors, design detailing.