How to repair a hardwood floor for D.I.Y’s and contractors.

This article will teach you how to repair a hardwood floor. Before you start, make sure you know a supplier of this same size and species of wood floor. Take a sample to your hardwood floor supplier that caters to tradesmen. The salesmen in some floor boutiques have limited knowledge, so you’ll have to find a hardwood floor specialty shop. Or a carpentry-cabinet making shop that is willing to do a small run of boards, if they turn out to be an odd size or species.

If you are repairing a prefinished floor, go to the dealer of that brand, in your area. If you don’t know the brand, look on the back of the board, it will sometimes be stamped there. Hopefully they will have the same size and color available in small quantities if this is a minor fix up of a few boards. You may find that the minimum order is about 20sq. ft. for most prefinished floors, nested in a box.

Unfortunately, I have found that as little as 5-6 years after a new floor is installed, some prefinished wood floor manufacturers will have changed their stain color just a little. Or if you are really unlucky the stain will have been discontinued or the company is now out of business. This may have a dramatic negative effect on the blending in of your repair. The solution in some of these cases is to repair the floor with unfinished wood, then sand and refinish the whole floor.

But the wise homeowner will have saved a box or two of the original material, and of course this will look much the same as the rest of the floor. The only difference may be a lightening of a dyed stained floor (dye stains are not very colorfast, pigment stained wood is better). Or a darkening of the finish or in a case of American Cherry, a darkening of the original wood itself, when exposed to sunlight. In all these cases it’s best to do the repair anyway, and let time age the new patch.

Then, take a good look at the run of the rest of the floor. Is it made up of long boards or a bunch of short ones? It will be your task to make the repair invisible. Using a pencil, mark off where you think you should cut the new joints in the hardwood, so that when replaced, the floor will look normal, not patched. I cannot teach you the art of staggering floorboard joints by the written word just use your artistic eye and imagine how much of the old floor you have to cut out for this effect. You may find that if the room is short it may be worth removing some pieces to the wall. But judge for yourself. Try, whenever you can to use the joints already in the floor, this will save you lots of cutting.

Once you have decided where to cut the boards, scribe a line on the face using a flat carpenter’s square. I use a sharp utility knife for this and go as deep as I can. Then using a very sharp chisel cut down on the line with the bevel of the chisel facing the waste side of the board; this will keep the line straight. You don’t need to strike too deep, as you will be taking out the wood in stages. Using the bevel side of the chisel down remove the first level of wood from you cut by angling a cut to the line. Always use a wooden mallet with a chisel. Repeat the cut and removal until you reach the subfloor. Do the same thing to the opposite end of the board. You can make all your cuts now if you wish and remove the boards later.

Remove the wood by splitting the board in thirds and the middle third should come free. If you got lots of space and courage you can use a circular saw to do this if it’s set for barely the depth of the hardwood. You can even saw out the boards by cutting across a few of them and remove all the little pieces. You will have to dig out the left over tongues and grooves with an awl, and use nail pulling pliers ( #64K02.01) to lever out the nails in all the nooks and crannies without damaging the face of the good floor. Vacuum up all the debris and make sure their or no bits of waste left.

Start the repair as if you are installing the floor with the tongue forward and the groove toward you. Mark off the board by butting one square end to the start of the gap and pencil mark it on the other end. Mark it with a square and then cut, leaving the line on the board. Angle this cut downward ever so slightly so it will fit easier. If you have to remove a bit more wood, this will be easier to sand off, when cut at this angle. But it only needs to be one degree. The new wood will not always fit the way it is because of the groove. You will need to remove some or the entire bottom of the groove to fit the new wood where needed. Just break it off with the pliers.

If it is a prefinished floorboard be sure to bevel the end that you have just cut, using fine sandpaper. You will have to touch these up later, with the touch up kit they provided with this floor (the installers did include a touch up kit, with this rather pricey floor, didn’t they?).

It is best to plan the initial repair cuts in a way where the first replacement board is the longest and the rest shorten. This will allow you to leave most of tongue and grooves of the new replacement boards intact. But do what you can. You will have to face nail the last repair board (and others I’m sure) by pre-drilling or try a nail spinner ( #99K20.01) Whenever you can try to blind nail the hardwood into the tongue, but the for last board, you have break the bottom of the groove off. You can easily do this with a pair of pliers (nail pulling pliers work the best). Then it will slip into place tongue first. Always use spiral-finishing nails, every 6-8″, which are set and filled with colored latex filler matching the final color of the finished boards.

I would even suggest this for a prefinished floor. You should be able to get matching putty filler for your type of floor. JUST BE SURE TO WIPE ALL THE EXCESS OFF BEFROE IT DRIES, OR A MESSY FILM WILL APPEAR ON THE FLOOR. When the latex filler dries on a prefinished floor you can see the dull spots of this filler, and these will need a drop of two of finish just in the filled holes. A lot of so called professionals repair prefinished floor by gluing down almost all the pieces to the subfloor, even some using two part epoxy. DON’T be tempted by this quick an easy method, it will create a dead unflexible spot in the floor, causing unnatural seams to form or worse yet a buckled floor during humid weather.

On sand-on-site floors you will notice that the new wood is higher than the original floor, so in almost all cases you will have to sand this flush with the old surface. This will be easy if you are sanding the whole floor, but a bit tricky if you are trying to blend in a small spot. Use a floor edger machine, and with the finest paper that will work (80 grit would be best) gently sand the repaired boards down flush. Use a vibrator sander to take the 80 grit sanding marks out, and hand sand with 100 grit until the area is really smooth. You will them have to determine just what your floor finish is (read my article in the Floored News about floor maintenance, the second part) and touch it up with the matching finish. This could prove to be difficult if the floor has been stained. You will have to purchase a few small cans of stain and try to blend in a matching color. If you find that this has formed a halo around the repair area, you have colored some of the old finish. You will need to remove some of the stain form the edge of the repair with solvent, a tricky job even for us pros. Some pros mix the stain with some floor finish to avoid this when staining, but I prefer to use the stain as it should be used.

Or you can avoid the sanding altogether, and use a scraper to level the boards. There is a new tool available at Lee Valley Tools ( called a floor scraper. I haven’t tried it yet as of this writing, but it looks promising. It’s a copy of an old design from 1911, and has a ball swivel adjustment that lets you two handedly scrape at any angle. Go to the web site and type in Prod. #05K21.01. It’s a little pricey, but it’s based on a cabinet scraper, not a cheap paint scraper. And I cannot remember being disappointed by any of Lenard Lee’s tools yet.

So there you have it I’ve talked you through (or out of) a repair of a hardwood floor. We hope to have a video (if we can find a sponsor) of this process, as not everybody can follow a written account of such a tricky job, but I hope I’ve done my job well.