- Twisted, bowed, warped or split floor boards.
- Floor board fasteners have loosened.
Another alternative is to apply weight to the floor and add a block on both sides of the floor joist using screws and construction adhesive, as shown in Figure 12. Either a square or triangular block can be utilized. It is important that you know the thickness of the sub-floor to avoid the possibility of having the screws protrude through the top of the floor.
Figure 12 - Using blocks to repair a sub-floor that is not fastened to floor joists
Figure 13 - Metal angle bracket
Avoid using metal angle brackets (Figure 13) rather than the wood blocks. The key to the strength is in the construction adhesive. Metal brackets do not adhere well to construction adhesive.
In some cases squeaks are caused by floor boards that have twisted, bowed, split or warped.
A floor board that has twisted, bowed or warped is next to impossible to bring back into shape and the only rational solution is to replace the board. Matching can be a problem, however a search of scrap yards and companies that specialize in saving demolished buildings may have just what you are looking for.
A board that has split, as shown in Figure 14, has some potential for being repaired.
Figure 14 - Split in floor boards
Install a piece of plywood, a minimum of 5/8 inch thick, using construction adhesive and wood screws to the underside of the floor tight between the 2 floor joists. Under the plywood use a wood block the length of the plywood support, fixed to each floor joist and the plywood using construction adhesive and wood screws, as shown in Figure 15. The plywood should cover a minimum of 2 boards on both sides of the split.
Figure 15 - Repairing split in floor boards
Once the construction adhesive has completely dried, fill the surface of the split with appropriately colored wood fill and sand flush.
If you have a floor with spring, it is not unusual to have the fasteners that hold down the floor boards loosen. As a general statement resetting the fastener, driving the nail back into the joist or tightening the screw will not provide a permanent fix as the hole's gripping power has been weakened as the fastener was raised.
Figure 16 - Correct angle to drive nails into floor boards
Figure 17 - Nail sets
The best solution to the problem is to set new nails or screws through the floor boards and into the floor joists, as shown in Figure 16. Spiral or ring shank finishing nails are the simplest fastener and yet will provide a lot of strength. If possible drive the nail at an angle into the floor board and into the joist. The length of the nail should be approximately 3 times the thickness of the floor board. With a 1/2 inch floor board use a 1 1/2 inch nail. With 5/8 inch floor boards use a 2 inch nail.
Use a nail set (Figure 17) to seat the nail slightly below the surface of the floor board. Then fill with an appropriate colored wood fill, sand, and the repair is complete.