Cross-bridging is a special way to join floor joists to prevent them from warping. The floor joists are the long thick boards you usually can see on your basement ceiling that run diagonally across the floor under the plywood. Cross-bridging is one of the most effective ways to prevent them from warping.

  • Make a diagram on a sheet of graph paper with your floor joists and where the cross-bridging will be. Most of the time they are put in with 1-3 feet between each other. Your graph will help you figure out how many you will need.
  • Measure the floor joists from the plywood of one board, down to the bottom of an adjacent one.Cut out the number of boards you will need to complete your project.
  • Cut each end of these boards at an angle that will let it fit snuggly between the floor joists at a cross angle.
  • Use a nail gun on the end of each board twice to keep it in place.

Installing Cross-Bridging

The cross-bridging technique is bound to be confusing until you have tried it a few times. Once you are finished, they should look like an “X” inside of your floor joists. One board will be behind the other, and they might not make a perfect “X”.