bridging

pieces of metal or wood that are fitted in pairs across the space between floor joists, each attached from the bottom of one joist to the top of the adjacent joist, and crossed to distribute the floor load by stiffening and holding them in place. Solid blocks of wood the same width as the joist may also be used as bridging when installed tightly between the joists. Also called cross bridging, floor strutting, herringbone bridging, or herringbone strutting