Wood Floor Cracking: Causes, Fixes, and Prevention

Hardwood floors are a timeless investment, but sometimes homeowners notice wood floor cracking or even wood floor separating between the boards. These issues don’t just affect appearance—they can also point to deeper moisture or installation problems.

This guide explains why wood floors crack, how to fix the problem, and what steps to take to prevent it in the future.

Cracked wood floor showing signs of wear

Why wood floors crack and separate

Wood is a natural material, and it constantly expands and contracts as humidity and temperature change. When balance is off, cracks or gaps appear.

Common causes include:

• Low humidity – Dry winter air pulls moisture out of wood, causing shrinkage.

• Excess moisture – Leaks or high humidity cause swelling, then cracking when the floor dries.

• Improper acclimation – If wood isn’t acclimated before installation, it may shrink or expand unevenly.

• Aging – Older floors naturally develop small cracks as part of wear and tear.

According to the National Wood Flooring Association (NWFA), controlling humidity between 30–50% is critical for avoiding floor damage.

Wood floors aren’t static—they “breathe” with the environment, and that’s often the root cause of cracks.

Well-maintained wood floor showcasing its beauty

Wood floor cracking vs wood floor separating

While often used interchangeably, the terms describe slightly different problems:

• Wood floor cracking: Visible splits in the surface of the planks themselves.

• Wood floor separating: Gaps appearing between boards, often seasonal.

Both can happen together, especially when environmental conditions are unstable.

How to fix wood floor cracking

1. Control indoor climate

• Use a humidifier in winter and a dehumidifier in summer.

• Keep temperatures steady to avoid rapid wood movement.

2. Fill small cracks and gaps

• Apply wood filler or putty for minor cracks.

• For separating boards, flexible gap fillers can disguise seasonal movement.

3. Refinish damaged boards

If cracks are shallow, sanding and refinishing can restore appearance.

4. Replace boards if necessary

Severely cracked planks may need replacement. A professional can weave in new boards without replacing the entire floor.

The U.S. Forest Products Laboratory advises against using rigid fillers on active floors, as they may crack again with seasonal movement.

Small seasonal gaps are normal. Large, permanent cracks usually signal a moisture problem.

Repair process for cracked wood floor

Preventing future problems

• Acclimate new wood before installation (let it sit indoors for 5–7 days).

• Seal floors properly during refinishing to protect against moisture.

• Clean with minimal water—avoid wet mops that soak into seams.

• Inspect yearly for leaks or water damage near kitchens and bathrooms.

FAQ

Why is my wood floor cracking?

Because of changes in moisture or humidity, improper acclimation, or natural aging of the wood.

What’s the difference between wood floor cracking and separating?

Cracking is when planks split, while separating is when gaps form between boards.

Can I fix wood floor separating myself?

Yes—minor gaps can be filled, but larger or permanent ones may require professional repair.

Will cracks in wood floors get worse?

If the cause is moisture imbalance, yes—controlling humidity helps stop the spread.

Is wood filler a good solution?

For small cracks, yes. For wide gaps or active floors, flexible fillers are better.

Final verdict: dealing with cracked wood floors

If you’re noticing wood floor cracking or wood floor separating, the first step is diagnosing the moisture issue. Control humidity, fill small gaps, and replace severely damaged boards if necessary. With the right maintenance, hardwood floors can remain beautiful for decades. 🌳✨