You can't repair a warped laminate floor in the same way you can a warped hardwood floor. Laminate planks aren't solid, and if you try to sand one to flatten it, you'll wear through the plastic coating in no time, exposing the core and ruining the plank. In fact, when a laminate floor is bubbling at the seams or crowning in the middle, replacement of the damaged planks is your only option.
You can use one of two procedures to replace a warped plank. The first is to disassemble the floor back to the one you want to replace, and the other is to cut the plank out of the floor. The first procedure is preferable when warping occurs near the tongue-edge of the floor. Otherwise, get out your circular saw and start cutting.
When to Replace Laminate Planks
Not every defect calls for a major repair. If laminate flooring feels bouncy, it could be because the underlayment is too thick. This isn't a major problem, and you're probably better off just learning to live with it. On the other hand, bounciness can also be the result of warpage. A laminate floor bubbling at the seams, or one that's warped, probably got wet, and moisture is a laminate floor's biggest enemy.
Forget what you might have heard about fixing warped laminate planks with a hair dryer. At best, that only dries out the material, but it won't restore the floor. You can't iron a laminate floor either. You have to replace the damaged planks, which is something you also have to do if a plank cracks or the surface delaminates.
When to Disassemble the Floor
Laminate flooring snaps together, and it also unsnaps, but only in one direction. If you're going to disassemble a floor, you have to start on the edge of the floor toward which the tongues are facing. The best way to determine the tongue direction is to remove a baseboard and look at the edge of the flooring.
The tongue is the lower part of the locking system, and if that's what you see, disassembly can start on that side of the room. Lift the edges of the planks in the first row to disengage them from the adjacent ones. It's best to remove an entire row before moving on to the next one or you'll have problems reassembling the floor.
Work your way back to the damaged area of the floor, remove the warped planks and replace them with new ones. Keep in mind that old boards tend to fade, so the new planks may look a little out of place. One way to help them blend is to stain the entire floor when you've finished the replacement, then give the floor a new coat of finish.
Cutting Planks Out of a Warped Laminate Floor
When a warped plank is in the middle of the room and there's too much furniture to move, the best strategy is to cut it out. You can do this with a circular saw set to cut to a depth of 1/4 to 1/2 inch.
Cut a line down the middle of the damaged plank, stopping short of the ends, then splay out diagonal cuts to each of the corners. Use a pry bar to pry out the pieces, being careful to leave adjacent planks undamaged.
Prepare the replacement plank by cutting off the bottom part of the groove from one side and both ends. You can now lock one side of the board into the adjacent plank, spread glue on the remaining part of the groove and lower the plank into place. Set a weight on it to hold it down while the glue sets.