Hardwood Floor Gaps: A Contractor’s Guide
Hardwood Floor Gaps: A Contractor’s Guide
Hardwood floors move.
Gaps are not automatically a problem — but filling them incorrectly is.
If you’re seeing gaps open during winter, read:
👉 Why Hardwood Floor Gaps Happen
Before choosing a product, you need to understand:
• Why the gaps formed
• Whether the floor is stable
• Whether they should be filled at all
• Which system fits your situation
This guide walks you through it step by step.
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Step 1: Understand Why Gaps Happen
Most gaps are caused by moisture loss and seasonal movement.
Some are normal.
Some are installation-related.
Some are structural.
Start here:
👉 Why Hardwood Floor Gaps Happen
https://www.groundfloorsupply.com/pages/why-hardwood-floor-gaps-happen
Step 2: Choose the Correct Filler
Not all fillers are interchangeable.
Stable floors use hard trowel fillers.
Unstable floors require flexible systems.
Finished floors need a different approach entirely.
Before buying anything, review:
👉 Gap Filler Selection Guide
https://www.groundfloorsupply.com/pages/hardwood-floor-gap-filler-guide
Step 3: Apply It Properly
Most filler failures happen because of:
• Poor cleaning
• Skimming instead of pressing deep
• Rushing dry time
• Filling seasonal gaps
If your floor is stable and ready for repair:
👉 How to Fill Hardwood Floor Gaps (Step-by-Step)
https://www.groundfloorsupply.com/pages/how-to-fill-hardwood-floor-gaps
When Not to Fill Gaps
If the gaps:
• Open in winter
• Close in summer
• Are part of a wide plank aesthetic
Leave them alone.
Hardwood is a living material.
Movement is normal.
The goal isn’t to stop movement — it’s to work with it intelligently.
Contractor-Grade Materials
Ground Floor Supply carries:
• Professional trowel fillers
• Flexible gap systems
• Spot repair solutions
• Full sanding and finishing systems
We don’t sell hardware store shortcuts.
We stock what contractors use to avoid callbacks.
If you’re unsure where to begin, start with diagnosis.
The wrong filler is worse than no filler.
Hardwood Floor Gaps FAQs
Are gaps in hardwood floors normal?
Yes. Small seasonal gaps are normal, especially in winter when indoor humidity drops. If gaps close again during humid months, they should generally be left alone.
Why do hardwood floor gaps get bigger in winter?
Cold air holds less moisture. When indoor heating runs continuously, relative humidity drops and wood shrinks across the grain, creating visible gaps.
Should I fill gaps that close in summer?
No. Filling seasonal gaps often causes cracking, edge bonding issues, or finish failure when the boards expand again.
If you're unsure whether your gaps are seasonal, read:
👉 Why Hardwood Floor Gaps Happen
What size gap can be filled in hardwood floors?
Hairline and small stable gaps can often be filled successfully. Larger or unstable gaps require flexible systems. In some cases, sliver repair is a better option than filler.