Why Your Floorboards Have Gaps (And the Easy Ways to Fix Them)
Gaps between floorboards can be annoying. They collect dust, let in drafts, and make an otherwise nice floor look worn out. The good news is that most gaps are fixable, and many don’t require ripping up your floor or hiring a pro.
Whether your floorboards have shifted over time or the gaps come and go with the seasons, this guide will walk you through simple, realistic ways to fix them.
Why Floorboard Gaps Happen
Before fixing the problem, it helps to know why it’s happening.
Most gaps are caused by natural movement. Wood expands when it’s humid and shrinks when the air is dry. In colder months, heating dries out the air and boards pull apart. In summer, they often swell back.
Other common causes include:
- Older flooring that has settled over time
- Poor installation
- Changes in humidity levels
- Subfloor movement
If the gaps appear and disappear throughout the year, that’s usually normal. Permanent gaps may need a more lasting fix.
Check the Size of the Gap First
Not all gaps should be treated the same.
- Small gaps (hairline to a few millimeters): Easy to fix and often cosmetic
- Medium gaps: Can be filled or closed with simple tools
- Large or spreading gaps: May point to bigger issues
Once you understand what you’re dealing with, select the appropriate method below.
Fix Small Gaps With Wood Filler
Wood filler works well for narrow gaps that don’t change much.
How to do it:
- Clean the gap with a vacuum or brush
- Choose a filler that matches your floor color
- Press it into the gap with a putty knife
- Wipe off excess and let it dry
- Lightly sand if needed
This is a quick fix, but keep in mind that filler can crack if the boards keep moving.
Use Rope or Twine for Wider Gaps
This old-school method works surprisingly well, especially in older homes.
What you’ll need:
- Cotton rope or twine
- Wood glue
- Putty knife
Steps:
- Measure the gap width
- Dip the rope in glue
- Press it firmly into the gap
- Trim the excess
- Stain or seal to match the floor
It flexes better than filler and holds up longer in active floors.
Try Wood Slivers for a Clean Look
For gaps that are too wide for filler but not huge, wood slivers are a solid option.
Cut thin strips of wood to fit the gap, glue them in place, and sand them flush once dry. This blends well and looks more natural than filler alone.
Reduce Gaps by Controlling Humidity
If gaps come back every winter, the real issue may be dry air.
Using a humidifier can help maintain steady moisture levels and reduce seasonal fluctuations. Aim for indoor humidity between 35% and 55%.
This won’t fix existing gaps overnight, but it helps prevent them from getting worse.
When to Call a Professional
If gaps are:
- Very wide
- Growing quickly
- Paired with squeaks or uneven boards
…it’s worth getting a professional opinion. There could be subfloor or structural issues that need attention.
What Not to Do
- Don’t force boards together with nails or screws
- Don’t use hard fillers in areas that move a lot
- Don’t ignore large gaps that keep spreading
Quick fixes can make things worse if used in the wrong situation.
Final Thoughts
Gaps between floorboards are common, especially in homes with real wood floors. Most are harmless and easy to fix with simple tools and a bit of patience.
Start by understanding why the gaps are there, choose the right fix for their size, and focus on solutions that work with your floor instead of against it.
A little effort now can make your floors look better, feel warmer, and last longer.