What You'll Need:
- Power screwdriver
- Wood screws
- 2x4-inch lumber
- Saw
- Tape measure
- Tape
- Level
- Shims
When you are walking on the floor, you will be able to hear where a squeak is, but you can also feel it. As you walk, the floor should be sturdy. If there is movement under your feet, then this can be a loose floor joist. Since it is sometimes hard to orient yourself under the floor, it is a good idea to count your steps from a familiar spot. This way, when you are under the floor, you can easily find your way to the troubled areas.
Step 2 – Sagging Floor Joists
When you reach the underside of the floor, you will be able to see several things. You will have the floor joists which cross one another to form a grid. On top of the floor joists is the subfloor, which is typically a sheer or sheets of plywood. On top of that will be your main floor. The floor joists are to be level and any that are not level are sagging. You can also tell because you will see a gap between the joists and the subflooring. To fix this problem, add several screws to the area where the joists are sagging. When you add the new screws do so at an angle and make sure they attach to the subfloor. As you add the screws, the gap between the subfloor and the joist will close up. You can also slide several shims between the subfloor and the joist and then add the screws to brace the joists.
Step 3 – Bowing
Over time, your floor joists can bow or bend from years of use. When this happens, the joists will not be level but they also may not be away from the subfloor but instead curving away from them. This lack of support in certain areas of the floor can be trouble. Use the tape measure to determine the space between joists. Cut the 2x4-inch board to this size. You want one piece for each side of the warped joist. Place the cut board between the joists and hammer in place, and then nail it to the joist and the subfloor. Repeat with the other side of the joist. This will brace the joist and push it back in place.
Source: www.DoItYourself.com