Hardwood Floor With a Loose Sagging Board

Identify the Cause

• Identify the cause of the problem so you will know how to tackle the repair. For example, perhaps a recent plumbing or roof leak left moisture trapped on the subfloor. Moisture imbalance, or having more moisture on the bottom of the board than on the top, is a common cause of sagging. Moisture absorbed by the board causes the ends to pop up, thus causing a loose and sagging board. Additionally, if someone spilled liquid on the floor and did not mop it up, the wood will warp as it absorbs the liquid.

Tackle the Underlying Cause

• If moisture is the problem, such as from a bathtub overflow or plumbing leak, allow the subfloor to dry completely before repairing any damage to the first floor ceiling. People who live in climates with year-round humidity may have sweating on underlying concrete foundations. You may need a professional contractor to deal with this problem. If the sagging is a weak spot in the board, you should replace it.

Wood Density

• Some trees produce much denser and stronger wood than others, while other species have fewer wood fibers or excessively knotty wood. A budget hardwood floor is just as beautiful as its expensive counterpart, but more prone to sagging under heavy weight. Old factories, especially in the northeastern states, have wood floors. You may need to replace the floor with a stronger wood if heavy equipment is the problem.

Routine Maintenance

• After you have repaired or replaced the warped board, wash and seal the floor to help protect it from future spills. If a leak caused the damage and not humidity, you should not have any further problems. If humidity was the culprit, follow the recommendations of the contractor who repaired the damage.