How to Fix Gaps on Hardwood Flooring?

Like most materials, hardwood flooring expands and contracts with changes in humidity to form gaps. It expands in low humidity and contracts in high humidity. 

Gaps in Hardwood Flooring

Other factors that cause gaping in hardwood are:

  • Milling errors.
  • Poor installation of your hardwood flooring.
  • Weather changes.
  • Loss of moisture content in your hardwood flooring.
  • Radiant heating. 
  • Indoor humidity imbalance.

Sometimes flooring is installed in cold seasons, months later in summer small gaps will start appearing. Good thing is that these gaps will close back up after some time.  

With these small gaps, no need for repair, but if you notice larger gaps, contact a professional immediately. The best time to make repairs for gaps in your hardwood flooring is usually the month of April and October.

Older hardwood floors are the easiest to notice gaps. Observe if these gaps will be visible throughout the year. If you are certain that these gaps are permanent, it is best you make arrangements to fill them back up.

Gaps trap dirt and make your hardwood flooring appear dirty all through. Larger gaps are a tripping hazard.

When Should you Fill Gaps on Hardwood Flooring?

The common way used by experts to determine when to fix gaps on hardwood flooring is using a Nickle.

Nickel Method

If a gap is wide for a Nickle to fit standing upright, fill those gaps. The best time to perform this experiment is in humid seasons when the gaps are narrow.

How to Fix gaps in Hardwood Flooring

When fixing the gaps in hardwood flooring, do this without losing the aesthetic value of the floor. Make sure the material you fill with matches the existing floor.

Below are the most used methods of repairing gaps in hardwood flooring.

  1. Using filler strips.
  2. Rope strips method.
  3. Wood putty method.
  4. Sawdust and resin filling method.

Method 01: Wood filler Strips

Measuring and cutting

Measure the size of the gap, transfer the measurements, and cut wood strips as precisely as possible using a hand saw. 

When you are cutting hardwood flooring wear protective goggles and gloves.


Clean the gaps and make sure all dirt has disappeared. Scrap and vacuum for best results.

Apply wood glue on the cut wood strips and fix gently the gaps. To make sure it is perfectly installed hit it gently with a hammer. Wipe off excess glue and give it time to dry.


Once the glue is dry, sand any high areas to make sure the strips you’ve installed are in line with the existing floor, carefully not to damage the boards nearby.

Once they level, stain the areas to achieve a matching finish all over the floor.

Wood filler strips are a permanent solution to gaps in hardwood flooring and have a very attractive end result.

Things you will need:

  • Wood strips matching the existing hardwood flooring.
  • White Wood glue.
  • Wood stain.
  • Sandpaper.
  • Tape measure.
  • Table saw.
  • Handsaw 
  • Safety goggles and gloves.
  • Hammer.

Method 02: Natural Rope Strips

Cleaning the gaps.

Carefully remove dirt trapped in the gaps with a vacuum cleaner and scrape with a putty knife. Repeat the process until the gaps are clean.

Cutting and staining the fibers.

Make sure the rope you use is natural; jute or cotton preferably. Synthetic fibers do not accept stains.

Using a utility knife, cut the rope to a dimension that is slightly longer and larger than the gap. Pour wood stain matching the existing hardwood in a bucket or in a clean food container and dip the rope fibers.

Once the rope is fully saturated, remove it and stretch it out on cardboard under a shade and let it dry completely. Do not dry out on excess sunlight or heat because it will ignite the rope when using an oil-based wood stain.

Fitting and finishing.

Pull the rope along the gap and then force it into the gap using a putty knife starting from one end and then along the gap.

Stop when the rope is slightly below the hardwood flooring surface. Trim the rope using a utility knife to make good.

Things you’ll need:

  • Natural rope fiber.
  • Wood stain
  • Utility knife.
  • Bucket/clean food container.
  • Putty knife.
  • Vacuum cleaner.

Method 3: Wood Putty

This method works best on smaller gaps, although most often than not if not properly installed it may crack in the dry season.

Wood putty is ideal because it is available in many colors, and it’s easy to find one that matches your hardwood flooring.

Clean the gaps

Clean the gaps, careful not to damage the edges of the existing hardwood flooring boards. Removing dirt makes the wood putty hold well.

Mix and Apply wood putty.

Mix and evenly apply the wood putty in the gaps using a putty knife, carefully not to scratch the hardwood. Use a piece of stick and work the putty in circular motions to force it into the gap.


Wipe off excess putty with a soft cloth and let it set completely before walking on it.

Things you’ll need:

  • Wood putty matching the existing hardwood flooring.
  • Putty knife.
  • Soft cloth.

Method 04: Sawdust and Resin

This method is commonly used for smaller gaps, about and less than 5 mm. Use sawdust almost matching the existing hardwood flooring, unless you have some that remained during the installation of your floor.

Cleaning the gaps

As previously described, scrap and vacuum off the dirt between the gaps, carefully not to damage the surrounding hardwood flooring to receive the filler.

Mix and apply.

Pour sawdust and the clear resin into a bowl and stir using a spatula to obtain a thick putty-like consistency. Clear resin is available at any wood floor supplier store.

When it is well-mixed scoop and introduce consistency in the gaps.

Finishing and making good.

Wipe off any excess and let it dry. If necessary, apply some finish/wood stain to match the rest of the floor.

The good thing with this method is that it dries evenly and faster, giving a smooth and color-matched end result.

Things you’ll need:

  • Sawdust matching the existing hardwood flooring.
  • Clear resin filler.
  • Plastic bowl/bucket.
  • Spatula.

How to fix Wider Gaps on Hardwood Flooring

All the above methods can be used to fill wider gaps, but some like filling with natural rope fiber are time-consuming and won’t give a beautiful end product.

The best permanent solution and one that does not compromise your hardwood flooring’s aesthetic value is using putty or paste.

Wood filler strips are ideal but should only be installed in humid weather when the gaps are narrow. This assures you that during hot weather the boards will not crack or split during expansion.

Below are Ways How to Prevent Gaps in Hardwood Flooring

  1. During the installation of your hardwood flooring, place an underlayment paper to prevent moisture from rising from the subfloor through rising damp.  
  2. Properly seal the seams between your hardwood flooring to avoid the absorption of moisture.
  3. If need be, invest in a digital hygrometer and monitor your room’s humidity levels. Maintain them at 30%-50%.
  4. Use hardwood flooring that has high UV and heat resistance.
  5. After purchasing your hardwood flooring, let it sit for about 10 days before installation. 

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