Your laminate floor used to lie perfectly flat, and now there is a ridge running along a seam, a hump in the middle of the room, or planks lifting near a doorway that move when you step on them. Buckling can appear almost overnight, often after a spill, a humid stretch of weather or a new piece of heavy furniture, and it is natural to worry the whole floor is ruined.
This guide explains what makes laminate buckle and how to tell the causes apart, then walks through the fixes from the simplest (drying out and lowering humidity) to restoring expansion gaps and replacing swollen boards. You will also learn when the problem is under the floor and needs a pro.
Quick answer: Laminate buckles when it has no room to expand or when moisture swells the fiberboard core. First find and stop any water source and bring indoor humidity back into the manufacturer’s range. Then remove the baseboards and trim the plank edges anywhere they touch walls, cabinets or door casings to restore the expansion gap. Boards that have swollen from water will not shrink back and need to be replaced.
Why laminate floors buckle
Laminate is a floating floor: the planks lock to each other but are not fastened down, so the whole floor expands and contracts as humidity and temperature change. Its core is high-density fiberboard, a wood product that absorbs moisture. Buckling happens when the floor grows and has nowhere to go, or when water makes individual boards swell.
Missing or blocked expansion gap
Manufacturers require a gap around the perimeter and every fixed object. Shaw’s laminate installation guidance, for example, calls for a 1/2-inch expansion space and says the floor must not be fastened or bound in any way. If boards were cut tight to a wall, trapped under door casings, run under cabinets or an island, or pinned by quarter round nailed down through the planks, the floor eventually pushes up.
High indoor humidity
Laminate takes on moisture from humid air and gets slightly larger. Shaw specifies 35 to 65 percent relative humidity and 65 to 85 degrees F, with the HVAC running before, during and after installation. Long humid summers, homes left closed up without air conditioning, and basements are common places for humidity-related buckling.
Water from above
Spills, wet mopping, pet accidents, leaking dishwashers, refrigerator water lines and wet entry mats let water into the seams. The fiberboard swells at the edges, creating raised, rough or “mushroomed” joints. This kind of damage is permanent.
Moisture from below
Concrete slabs and crawl spaces can push moisture up into the floor. Without the vapor barrier the manufacturer specifies, planks may cup (edges higher than the center) or buckle across large areas. A hidden plumbing leak under the floor produces similar symptoms, often with a musty smell.
Uneven subfloor and long runs
Dips and humps make the locking joints flex every time someone walks over them. Over time, joints can loosen and peak. Very long runs or floors continued through several rooms without the transitions the instructions require can also build up enough movement to lift.
| What you see | Likely cause | First fix |
|---|---|---|
| Hump or tent along a wall or doorway | No expansion gap, floor pinned | Remove trim and cut back plank edges |
| Whole floor tight, buckling in humid months | High humidity plus small gap | Dehumidify, then restore the gap |
| Raised, rough seams in one area | Water from above swelled the core | Stop the water; replace swollen boards |
| Edges higher than plank centers over a large area | Moisture from slab or crawl space | Find the moisture source; check the vapor barrier |
| Soft spot or musty smell | Leak or wet subfloor | Shut off water, lift boards, dry and repair |
| Joints peaking where floor flexes | Uneven subfloor | Lift section, level subfloor, reinstall |
Tools and materials
- Moisture meter and a digital hygrometer
- Dehumidifier and fans
- Pry bar, putty knife and painter’s tape for removing baseboards
- Oscillating multi-tool or circular saw with a fine blade
- Pull bar, tapping block and rubber mallet
- Expansion spacers
- Replacement planks from the same product (check your spare box)
- Floor patch or leveling compound if the subfloor needs work
- Safety glasses, gloves and dust mask
How to fix buckled laminate, from minor to major
1. Stop the water and dry the area
If there was a spill or leak, wipe up all standing water, shut off the supply to any leaking appliance and run fans and a dehumidifier. The EPA advises drying water-damaged areas within 24 to 48 hours to prevent mold growth. If water has run under the floor, lifting a few boards near the wall helps air reach the subfloor. For sink-related leaks, see our guide to a leak under the kitchen sink.
2. Bring humidity back into range
Use a hygrometer to check the room. If it is above the range on your flooring’s instructions, run air conditioning or a dehumidifier and give the floor several days to a few weeks to settle. Mild, humidity-only buckling with no swollen seams sometimes flattens on its own once the air dries out, especially if you also restore the gap. In winter, the opposite problem is more common; our guide to ideal indoor humidity in winter covers the balance.
3. Restore the expansion gap
- Remove the baseboards or quarter round along the affected walls, numbering each piece for reinstallation.
- Look for spots where planks touch the wall, a door casing, a pipe, a cabinet base or a fireplace hearth.
- Mark a line that leaves the gap your instructions call for, and trim the plank edges with an oscillating tool or a circular saw set just to the plank depth.
- Check transitions: if a transition track or strip is screwed through the laminate, refasten it to the subfloor only.
- Give the floor a day or two to relax, then reinstall trim nailed into the wall, not into the floor.
4. Free pinned areas
Kitchen islands, built-in cabinets and very heavy furniture can lock a floating floor in place so it cannot move. If the buckling started after a heavy item was added, move it and see if the floor relaxes. For built-ins set on top of the laminate, the long-term fix is cutting the floor back around the base and leaving a gap, which is often a job for a pro.
5. Re-lay a buckled section
If the floor stays lifted after the gap is restored, or joints have popped apart, take up the planks from the nearest wall to the buckled area. Clean the joints, check the subfloor with a straightedge, fill low spots, and click the boards back together with spacers in place. Re-laying a few rows is very doable for a careful DIYer.
6. Replace swollen boards
Planks with puffed, rough or split edges will not go back to normal, even after drying. Replace them with boards from your spare box or the same product line. Most floors can be disassembled from the nearest wall to reach the damaged boards; for a plank in the middle of a room, a pro can cut it out and glue in a replacement with the locking lip trimmed off.
7. Fix moisture under the floor
Widespread cupping over concrete or a crawl space means the moisture source has to be fixed before new boards will last. That can mean adding the correct vapor barrier under the floor, improving crawl space ventilation or a vapor retarder, or repairing a leak. Laying new laminate over the same conditions will just repeat the damage.
Safety note: If water reached electrical outlets, cords or appliances, turn off power to that area at the breaker before you start drying. Wear gloves and a mask if you find mold under the boards, and call a remediation pro for large or recurring mold growth, especially if anyone in the home has asthma or allergies.
How to prevent laminate from buckling again
- Keep humidity steady within the range in your installation instructions, using air conditioning or a dehumidifier in summer.
- Clean with a damp, not wet, mop and wipe spills immediately.
- Protect high-risk spots with washable mats by the sink, dishwasher and entry doors, and put trays under plants and pet bowls.
- Never pin the floor. Nail trim to the wall and keep cabinets and islands off floating floors.
- Use the right floor for the room. Standard laminate is a poor fit for full bathrooms and laundry rooms; see our LVP vs laminate comparison.
When to call a pro
Call a flooring contractor, or a water damage company for active leaks, if you notice:
- Buckling across more than one room or the whole floor
- A soft, spongy subfloor or a persistent musty smell
- Water that keeps returning, suggesting a hidden plumbing or slab moisture problem
- Buckling under cabinets, islands or built-ins
- No spare boards and a discontinued product, which may mean a larger section must be replaced
For reference, HomeAdvisor’s laminate installation cost guide puts installer labor at about $2 to $8 per square foot, with typical installation projects running about $800 to $4,000. Water mitigation, mold remediation and subfloor repairs are priced separately and depend on how far the water spread.
Frequently asked questions
Will buckled laminate flatten on its own?
Sometimes, if the cause was high humidity and the boards are not swollen. Lowering the humidity and restoring the expansion gap gives the floor room to settle. Boards that have absorbed water and swollen at the edges will not return to flat.
Can I put heavy weights on buckled laminate to flatten it?
No. Weights do not remove the pressure causing the buckle and can break the locking joints. Restore the gap and fix the moisture problem instead.
Why is my laminate lifting at the seams?
Raised seams usually mean water has swelled the board edges, or the floor is being squeezed by a missing expansion gap. Swollen, rough edges point to water; clean seams that peak in a line point to pressure. An uneven subfloor can also make joints flex and lift.
How big should the expansion gap be for laminate?
It depends on the product. Shaw calls for 1/2 inch, and other brands specify their own gaps, so follow your installation instructions. The gap is needed at every wall and fixed object, including pipes, door casings and cabinets.
Can you fix buckled laminate without taking up the floor?
Often yes, if the problem is pressure. Removing the baseboards and trimming the plank edges to restore the gap can let the floor drop back into place. Water-swollen boards, though, must be replaced.
The bottom line
Laminate buckles when it is squeezed or soaked. Stop any water, dry the area within a day or two, bring humidity into the manufacturer’s range and restore the expansion gap wherever the floor is pinned. Replace boards with swollen edges, fix any moisture coming from below, and call a pro when the damage is widespread, the subfloor feels soft or the water keeps coming back.
