How to Repair a Crack in Wood Flooring
By Mike Ferraro, CGP

Whether it’s an old home or new, wood flooring can crack. Often times, the culprit
is excess humidity, causing the wood to absorb the moisture and swell. The swelling
causes extreme pressure build up which forces the planks to move. Since the tongue
and groove planks are usually fastened, and sometimes glued, they don’t move very
easily. Therefore, if one cracks, you can imagine the amount of force necessary to cause
the wood to crack.

First, check the humidity level in the home. Its best if the humidity is less than 45%. If
you find the humidity level high, you will have to take measures to reduce it, such as
installing a dehumidifier or air conditioning. Remember that too high a humidity level is
not healthy for either you or your home.

Attempting to repair the crack will be futile until the humidity level is under control.
Once you achieve and maintain the humidity to a healthy and safe level, you can begin
to fix the crack.

Here’s a method we use that is very often successful, makes little mess, and is relatively
quick and easy to do.

  1. Remove any debris from the crack and make sure all surfaces are dry.
  2. With a block of wood and hammer, place the wood block on the crack and lightly hit it. This will help return the wood to the correct position.









  3. Predrill screw holes about every 3” apart on the side of the crack that is higher than the other side.
  4. We use 3M Scotch-Weld epoxy adhesive DP-100. Using the epoxy gun, insert epoxy into the crack. It’s ok if a small amount of excess rises above the crack.









  5. Place washers on the Kreg screws and screw them into the holes until tight. Be careful not to over tighten. This should draw in the two sides of the crack.

















  6. Wipe off the excess epoxy with a clean cloth.
  7. Dry time may vary, but generally about ½ hour. We place a small fan on the crack to facilitate dry time.
  8. Remove the Kreg screws and replace with a small head wood trim screw. Drive these screws about 1/16th below the surface.









  9. Even though you wiped off the excess epoxy earlier, there is still a thin film on the wood that will prevent stain from adhering to the wood. So, using a small scraper, scrape the wood, then sand with fine grit sandpaper. Hint: do not over sand or sand too wide an area; the closer you stay to the crack, the better the stain match will be.

















  10. Save the sawdust to mix with a very small amount of epoxy to create wood filler to cover the screw heads. Apply with a small flexible putty knife. Let it dry then lightly sand.
  11. When dry, with a damp cloth wipe the area to remove dust. Let dry.









  12. If necessary, tape off any area that may get splattered with stain. Brush on stain and immediately wipe. If the repaired area is lighter than the original wood, reapply stain and wait about a minute, then wipe off. You may have to experiment to achieve desired color. Let dry about 6-8 hours.
  13. Brush on water-based polyurethane. Three coats will suffice; about two hours dry time between coats.









Mike Ferraro is president of Ferraro Builders, which specializes in designing and building luxury homes and timber frame homes. He is also Past President of the Grand Traverse Area Home Builders Association, an Energy Star Partner, and Certified Green Professional (CGP).



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