Bridging is the method of adding boards to the floor joists, in order to add support to the overall structure of the floor. Bridging is created by nailing small boards or wooden members at diagonal angles between the joists, in what would look from an eye-level view horizontally as X’s.
Reasons for Bridging
The reason bridging is used on a sub-floor is to add to the carrying power of floor joists. Proper bridging also prevents floors ‘creaking’ since it solidifies the floor form possible slight movement. In most cases, one inch by three inch wood stock is used in bridging. On larger floors, two inch stock is advisable.
Cutting Stock for Bridging
In cutting wood stock for bridging, a miter box is used, and the cut is made to create beveled ends on the wood piece, so that the angles will fit when nailed together.
Carpenters commonly will cut one end of the bridging piece, set it against the lower end of the joist, the cut the upper end accordingly, to make a tighter, accurate, custom fit for the bridging piece.