How to repair hardwood floors that have buckled
With proper installation, care and maintenance, a hardwood floor will look beautiful and hold its value for many years. But, changes in temperature and humidity cause wood to expand and contract. That’s when problems appear. Excess moisture can cause floors to buckle or “tent.” Because a floor is restrained by walls or adjoining surfaces, such as tile, the wood has only one direction to go—up. The center of the hardwood floor releases and buckles, and that section of flooring is no longer in contact with the substrate. Follow these expert tips to repair hardwood floors that have buckled:
Buckling most often occurs after a floor is flooded, but there are other causes. Failure to leave a large enough expansion gap around the perimeter of the room can contribute to buckling. On nailed floors, insufficient nailing, incorrect nails or incorrect subfloor construction can lead to buckling, and with glued floors, buckling can be the result of the wrong mastic, subfloor separation or subfloor contamination.
Repair a buckling hardwood floor at the first signs to prevent further damage and help avoid a major repair later. If you can get to the floor from below, you may be able to fix it without removing boards, but in most cases, replacement of the damaged area is necessary.
Before you repair the floor, find and correct the source of the excess moisture. Water damage could be a result of a cracked pipe, drainage problems, a leaky roof or high humidity inside the house.
A good repair should be invisible
If the homeowner does not have extra pieces of flooring, take a sample of the flooring to a supplier and find a match. If you are repairing a prefinished floor, go to the dealer. If you can’t find a match for a pre-finished floor, use unfinished wood of the same variety and stain it to match.
How to repair hardwood floors when there is access from below
Solution: Place a weight, such as a cement block, on the buckled board or boards. From below, drive a short screw, no longer than 1¼ inches, through the subfloor and into the buckled floor board. The screw should not go all the way through the hardwood. Once the screw has engaged it will pull the flooring down, eliminating the buckle.
How to repair hardwood floors without access from below
Remove the center piece of the board and grooved edge piece. Chisel out the tongue edge and pull the remaining nails.
With a pencil, mark the boards you need to replace where new joints should be cut. Set a circular saw to the exact thickness of the flooring. Make two parallel cuts the length of the board, ½ inch from the long edges and crosscut the center on an angle. With a sharp chisel, break the kerfs at the ends and chisel through the cross cut.
Remove the center piece of the board and grooved edge piece. Chisel out the tongue edge and pull the remaining nails. Cut the felt paper out of the exposed area and vacuum clean. Select replacement boards that are similar in color and grain pattern, and that have approximately the moisture content of the existing flooring. Fit the piece in the open space on edge and mark the exact length with a utility knife.
Use a miter saw to cut the piece to length. Cut off the bottom lip on the groove edge and groove end. Block plane the lower edge of the top groove lip on a slight angle. Trial fit the piece into place. Plane until you get a perfect fit.
Apply epoxy glue to the existing exposed tongue, into the groove of the opening in the floor, and to the subfloor. Roll the tongue edge into the groove and tap it with a scrap piece of flooring. Remove excess glue from the face of the wood. Put a weight on the new flooring for at least 45 minutes, and keep traffic off for 12 hours.
If you are repairing a larger area, blind nail most of the replacements pieces into place and glue the last board. Plan the initial cuts so the first replacement board is the longest. This leaves most of the tongue and grooves of the replacement boards intact.
Sand the replacement flooring with an edger using the last sanding grit applied to the floor.
Matching the floor’s finish
Sand lightly into the existing flooring to blend the perimeter.
Use a flooring scraper (¾ to 1½ inches wide) to smooth the repair, scraping with the grain.
Use a flooring scraper (¾ to 1½ inches wide) to smooth the repair, scraping with the grain. Scrape into the existing flooring a little further than the sanded area and along every other grain line. Hand-sand the area using 100 sandpaper, followed by 180 and 200. Sand with the grain.
Apply color-matched stain in the center of the sanded area and wipe from edge to center.
Apply color-matched stain in the center of the sanded area and wipe from edge to center. If topcoats have been applied to the existing flooring, wipe the stain off the finished edge with solvent. When the stain is dry, de-gloss the finish around the perimeter and apply finish over the repaired area. After drying, de-gloss and apply a second coat if necessary. For a more uniform appearance, de-gloss and coat the entire floor.
Other moisture-related problems
- Cracks and shrinkage can result from too little moisture.
- Cupping across the width of one piece of the flooring material leaves the edges higher than the center. It is usually caused by a moisture imbalance through the thickness of the board.
- Crowning, when the center of the piece of flooring is higher than the edges, caused when a cupped floor is sanded flat without eliminating the cause of the moisture imbalance.
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