How do I fix gapping in my hardwood floors in winter?

Gaps in the winter are completely normal and will close up when the humidity returns in the spring. To minimize it, use a whole-home humidifier to keep the indoor RH above 35%.

What happens if a floor cups?

If you catch it early, lowering the indoor humidity back to 45% using AC or a dehumidifier will often allow the wood to dry out and flatten naturally. If the damage is severe, the floor may need to be sanded flat.

Ideal Relative Humidity for Hardwood Floors

What happens if humidity is too high?

Wood is hygroscopic. In high humidity, the floorboards absorb moisture from the air and expand. This causes 'cupping', where the edges of the boards raise higher than the center.

What happens if humidity is too low?

In very dry winter air, the floorboards release their moisture into the air and shrink. This causes unsightly gaps between the boards and, in severe cases, checking or splitting of the wood.

Frequently Asked Questions

How do I fix gapping in my hardwood floors in winter?: Gaps in the winter are completely normal and will close up when the humidity returns in the spring. To minimize it, use a whole-home humidifier to keep the indoor RH above 35%.
What happens if a floor cups?: If you catch it early, lowering the indoor humidity back to 45% using AC or a dehumidifier will often allow the wood to dry out and flatten naturally. If the damage is severe, the floor may need to be sanded flat.