How to Fix a Cracked Door? (Step-By-Step Tutorial)

How to Fix a Cracked Door? (Step-By-Step Tutorial)

Have you noticed hairline cracks on your door? Humidity and temperature fluctuations cause wood to expand and contract, leaving splits on the surface of the door.

If you fix a cracked door early, you can prevent the splits from growing into huge crevices, which would otherwise compromise the door’s energy-efficiency. With a few inexpensive tools and materials, the job should be done in a few hours.


You will need the following tools and materials:

  • Putty knife
  • Dremel tool


  • Wood putty or filler
  • Epoxy sealer and adhesive
  • Wood spline
  • Sandpaper

Step-by-Step Guide on How To Fix A Cracked Door

Follow these simple steps to repair cracks on a solid door.

Step 1. Choose between wood putty and filler

Choose between wood putty and filler

Both wood putty and filler can help to repair door cracks but there are slight differences between the two materials.

  • Putty is flexible and does not dry hard. This is a good option if you do not plan to sand, stain, or paint your door.
  • Opt for filler if your door is already painted and will, therefore, need to be repainted after fixing the cracks. Unlike putty, filler dries hard and can be sanded.

Step 2. Apply filler onto the crack

Apply filler onto the crack

Wood filler offers a longer-lasting solution for dealing with door cracks. For the best results, be sure to choose good quality filler.

  • Use a putty knife to fill the crack with a small amount of wood filler. Do this for all the cracks on the door. Add more filler as needed to cover the entire crack.

Step 3. Allow adequate drying time

Allow adequate drying time

  • Scrape off excessive filler. The surface doesn’t have to be even—you will sand it later.
  • Give the filler enough time to dry. Good quality filler typically has a shorter drying time.

Pro Tip: Use a blow dryer to direct hot air onto the filled-in crack for the filler to dry faster.

Step 4. Sand the surface

Sand the surface

For a smooth finish, you will need to sand the surface where you applied the filler.

  • Use gentle strokes to sand the target area using medium grit sandpaper (60-100 grit) until the surface is even.
  • For a longer-lasting fill, reapply the filler and allow it to dry before sanding the surface again. Always use gentle strokes to avoid scratching the paint too much or causing dings on the door.

Step 5. Paint the surface

Paint the surface

  • Select a similar tone of paint to apply to the sanded area.
  • Be sure to use the correct painting technique to avoid leaving paintbrush marks on the door. If possible, paint using a roller with a velour cover instead of using a paintbrush. Rollers offer a more finished look compared to paintbrushes. That being said, a paintbrush is easier to use if you are painting the grooves of a paneled door.
  • Allow the paint to dry.

Step 6. Use epoxy glue for medium-sized cracks

Use epoxy glue for medium-sized cracks

If you are dealing with a medium-sized crack, wood filler or putty will not fix the damage. Opt for a stronger compound such as an epoxy adhesive.

  • First, fill in the crack with epoxy sealer. The sealer helps the adhesive to adhere.
  • Next, squeeze a bead of epoxy adhesive into the crack. The glue will expand and fill the crack. Therefore, a little does go a long way.
  • Let the glue dry then apply a final coat of sealer. Allow the sealer to dry.
  • Use fine sandpaper (120-220 grit­) to buff the surface. Paint or apply stain to the surface as needed.

Step 7. Fix large cracks using wood splines

Fix large cracks using wood splines

To fix large splits on the door, you will need more than just glue or filler. Inserting a wood spline into the split offers the most lasting solution.

  • Use a Dremel tool to clean and create space in the split so that the wood spline fits snugly.
  • Then, insert the spline into the split to test for size. Adjust the size of the spline until it fits tightly in the crack.
  • Remove the spline and fill in the crack with high-quality wood glue. Insert the spline into the crack. Use a rubber mallet to gently push the spline deep into the crack.
  • Chisel off the protruding edges so that the spline is flush with the door. Allow the glue to dry before sanding the area.
  • Paint or stain the door as needed.

That’s is all there is to fix a cracked door. Your door should now look as good as new.

Extended Tips

Below are additional tips to help you get the most from this project.

  • Prep your work area

Because this project involves sanding and painting, be sure to protect your floors with a dust cloth. You do not want filler, paint, or wood chaffing to ruin your floor or carpet.

  • Clean the door

Before getting started, wipe the door to rid it of dust. Filler, putty, and even glue will not adhere well to a dusty surface. Be sure to wipe the door after sanding and before painting or staining.

  • Use putty for stained doors

To fix hairline cracks on a painted door, it is best to use wood putty, as you won’t have to sand the surface. Simply fill cracks with a small amount of putty, wipe off any excess, and you are good to go.

  • Replace cracked plywood

Some interior doors are made of thin sheets of plywood, which is prone to cracking. In some cases, applying filler or putty will not permanently solve the cracking problem.

If new cracks appear or the old ones keep opening, consider replacing the entire sheet of plywood. Removing the old plywood should be easy given that the sheet is attached to the doorframe by a bead of glue.


Door cracks are common and are usually an easy DIY fix. However, small hairline fissures can quickly become gapping splits that require more work and in some cases replacing the entire door. Proper care and regular maintenance of your doors will prevent costly repairs.

Do you have a cracked door in need of repair? Leave your comments and questions below—we’d love to hear from you!

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