Replacing a board....the right way

April 2, 2016 Written by  Reuben Mitchell

Last week when resanding an existing 4 1/4 x 3/4 site finished walnut floor the usual unforeseen wood flooring headache occured. During the final buffer pass a large shake tore out of one of the boards. At first I just filled it, dried it fast with a heater and then applied the first coat. When I returned the next day as you can guess it did not look very good. I thought the usual, here we go another headache and more work. I entertained splicing in a "dutchmen" or piece of wood glued in to match but in the end the best solution is usually to replace the board. Once the decision was made the headache is typically not as bad as thought to be and the board replacement went quite quickly, here is how I did it.

This board was very long so rather than replace the entire thing I cut it to a workable length (less than 36 inches) it was close to being an "H" joint but we compromised slightly to carry out the repair. To do this I like to use a Fein cut plunge saw and an existing piece of flooring with a square end. I use masking tape to make two loops (or double sided tape) and place them on the floor to secure the loose board from moving. I then line up the loose board over the existing board and tape and kneel on the board to hold it so I can use the square end as a guide to run my Fein saw blade along. The board will give you a square edge, show you where the edges are to prevent cutting adjacent boards (often hard to see) and act as a guard to protect the existing board if you place it on the side of the cut that is remaining. I then use a skill or circular saw to cut the board to be removed lengthwise on both sides and at an "x" at both ends. This cut allows the middle and ends of the board to come out easily. I hammer a large screw driver into the remaining pieces then hammer it sideways to remove the remainder without dammaging the surounding boards. Vacuum and clean the opening and remove and paper underlayment from the subfloor.

Now it is time to prepare the new board for the opening. I like to hold the board on edge over the hole and butt one short end up tight to the existing board. Using a sharp knife I mark the exact length to cut, using a knife instead of a pencil gives a far more accurate mark and I usually only have to cut one time. I now cut the bottom of the groove off typically with a table saw and back bevel it, but have been know to break it off with pliers or a hammer and clean it up with a block plane as well. With a block plane I back bevel the top of the groove slightly to allow it to drop in easily, the board is now ready.

To install the board I like to use an MSPolymer or urethane flexible wood floor adhesive in a sausage gun applied to the subfloor for some extra security but it is OK not to glue it to the subfloor if you do not have any. Do not use construction adhesive as it will anchor the board too securely and not allow any expansion movement or white glue as it is too brittle and will fail. To secure the board in place if in a hurry I use 5 minute epoxy, if I can wait overnight a D3 style floating floor glue will work. Again do not use white glue or carpenters glue as it is very brittle and can crack or fail resulting in a noisy or loose repair. I mix the epoxy, put it into a 30ml syringe and apply a 1/16 inch bead to the top of the tongue of the exsiting boards, I do not apply the glue to the new boards tongue or exsiting grooves unless they are a loose fit as this extra glue will result in 3 board panelization and not allow proper movement.

When the adhesive is in place drop the new board in the opening. Use another board and hammer to sideways tap the tongue into the groove until in and then place a board on top of the new one ensuring you cover over the tongue side and tap it down. Tapping on an overlapping board will help prevent the top of the groove from cracking during tight installs which can be a common problem and result in having to start over.

If this is a prefinished floor apply a little filler as needed and you are now done. For a site finished floor you still need to sand it flat and in this case the floor was already sealed with a first coat so here is what I did. Using an edger I cut the repaired area flat with 100 grit abrasive being carefull to not leave any ripple or gouges. I then used a 6 inch Rotex style sander with 100 grit to remove and edger swirl and blend with the exisitng floor. With a cut in pad or brush I coated the repaired area feathering into the exsiting finish for a seamless repair.

Even though this repair occured after the final sanding of the floor careful preparation and the skill of a flooring professional resulted in a seamless repair and this contractor got to go home that night without worrying if the customer would notice the large spot of filler in the floor.


Reuben Mitchell