Q&A / 

How To Repair Hardwood Floor Cracks

Quick Column Summary:

  • Hardwood floor defect repairs
  • Cracks in hardwood repairable
  • Lighting highlights problems
  • Practice installing and staining flooring

DEAR TIM: I've got cracks between the tongue and groove boards of my hardwood floor in certain places. One of the locations is in front of my refrigerator where the ice maker supply line developed a tiny leak that went undetected for a month. Other places are in the middle of the room where no water touched the wood. Some of the individual pieces of wood are now humped. Can these be easily repaired or must the entire floor be refinished? I'm not looking for perfection, but it would be nice. Melinda B., Durango, CO

DEAR MELINDA: Many people suffer from hardwood floor defects just like you. The reasons are many, but the solutions are few. The good news is the cracks can be fixed so the floor looks brand new. Rarely do you have to refinish the entire floor, but in certain instances it's required.

Defects in most hardwood floors stand out like a sore thumb or a pimple on a forehead because of the flat shiny finish you see on most hardwood floors. The higher the gloss on a surface the more the surface will telegraph a flaw.

This hardwood floor got wet, swelled, then dried. Cracks are now telling the ugly tale. Photo Credit: Tim Carter

This hardwood floor got wet, swelled, then dried. Cracks are now telling the ugly tale. Photo Credit: Tim Carter

The reason for this is light and light reflection. When light hits a shiny surface it reflects at a certain angle. If the surface is not flat, in your case the humps in the boards are anything but flat, the light reflects off at different angles highlighting the hump. If the hardwood flooring had a matte finish, much of the light would be absorbed by the finish and you wouldn't see the hump.

I'm sharing this so you realize if you don't want to see the humps, you're going to have to at least sand and refinish that part of the hardwood floor. If your floor is like the one in my house, I have red maple flooring with no stain, you can get away with sanding an area and then just putting a clear finish on that part of the floor. I had to refinish part of my hardwood floor a few years ago and you couldn't tell where the floor had been sanded and refinished.

If your hardwood has a stain, you can sometimes sand and stain the sanded area blending in the repair job so no one sees it. I've done this on any number of occasions. It was not easy, but I did it. True professionals can do this repair as well.

The first step in this process is to clean the hardwood floor well so you can see the real color. If you're lucky enough to have a closet where the hardwood flooring is present, you want to experiment here with your stains and refinishing. If you can't get it right in the closet, you don't stand a chance out on the open floor.

The color of the stain when it's wet on the sanded hardwood just after wiping it with a rag is what it should look like when the clear finish is applied. This will help you get the color correct. If you can't seem to do this, always make sure the stain color is slightly lighter than the flooring. You can then add pigment to the clear finishes until you get it right. Once the color is correct, then you apply two coats of clear finish on top of the pigmented finish.

Filling the cracks in flooring can be daunting. The fillers almost always look worse than the crack itself. Some of the fillers don't take stain well. The other issue is the natural grain of the hardwood. When you fill a crack with filler, it's a mono-color-texture material. When it's stained, it look one color.

Your hardwood flooring has random grain lines that create its natural beauty. You'd have to take an eyeliner pen or similar device to create realistic grain lines in the filler to mimic the ones Mother Nature created in the hardwood flooring strips.

A professional would just invest the time to remove the swelled pieces of flooring and install new strips of hardwood with no cracks. A professional can sometimes do this in just a few hours if the area is small. Consider investing in this to get great results.

Another option is to bring in a furniture repair wizard. These master craftsmen and women have magic boxes that house an alcohol lamp, hard lacquers and other materials allowing them to fix deep scratches, dents, chips etc. in fine furniture. I can tell you I've had this done and it's impossible to tell where the furniture is repaired. Fixing a hardwood floor crack or two would be child's play for them.

If you decide to try to refinish a small section of the floor yourself and have never done this before, I beg you to purchase a small amount of hardwood flooring and install it on a piece of 3/4-inch wood in your garage. Get out your belt sander and sand the wood until it's as smooth as a piece of glass.

Practice staining and applying clear finish on this test area. When you feel it looks fantastic, then open the door to your home and have at it. Don't underestimate how hard it is to get professional results. The good news is if you make the floor look worse with your repair attempts, you can bring in a pro to bail you out. It' pretty hard to ruin a hardwood floor unless you sand too much of it away.

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