Flooring Problem
Vinyl Plank (LVP) Buckling & Peaking
Why is my vinyl plank floor buckling or peaking?
The Short Answer
What Causes Vinyl Plank Buckling?
A floating vinyl plank floor is not fastened to the subfloor. The planks click together into one connected sheet that sits on top, and that sheet has to be free to grow and shrink. Buckling and peaking happen when the floor needs room and does not have it. Two planks press against each other and the seam between them rises into a ridge, or a whole section lifts into a soft hump. Most of the time something is holding the floor in place: cabinets or a kitchen island set on top of it, baseboard or quarter-round nailed through it, a transition screwed down through the planks, or no expansion space left at the walls. Sun pouring through a slider and moisture coming up from a concrete slab are the usual triggers that push a tight floor over the edge.
The good news is that a buckled vinyl plank is usually not ruined. The wear layer and core are often fine, and once the floor can move again it may settle back down. The repair is about freeing the floor, not forcing it flat. Weighting a peak, gluing it, or adding more nails holds the pressure in, and it comes back at the next weak seam. Planks with cracked or chipped click-locks do have to be replaced, because a damaged joint will not lock flat again.
This is the opposite of separation. When a floating LVP floor shrinks and seams pull apart, see our vinyl plank separating page. Buckling is the floor pushing in on itself. Both often come from the same pinned or sun-heated floor, which is why the two sometimes show up in the same room.
How to Recognize Vinyl Plank Buckling
A raised ridge where two rows of planks meet, a hump that gives or bounces underfoot, or a run of planks lifting near a wall, a doorway or a sunny slider. It often appears or gets worse on hot afternoons and may ease off at night or in cooler months.
Root Causes
Why Vinyl Plank Buckling Happens
The floor is pinned in place
A floating floor has to move as one unit. The NWFA Installation Guidelines, written for floating wood floors on the same principle, say floating floors should never go where fixed cabinetry such as kitchen islands will lock the floor down. They say baseboard, base shoe, quarter-round and other trim must never be fastened to or through the flooring, and that T-moldings and thresholds should be anchored only to the subfloor. NWFA also notes that a load of more than 600 pounds on a single board, like a piano, a loaded entertainment center or a refrigerator, can keep the floor from floating. With one edge locked, the rest of the sheet has nowhere to go but up.
Missing or undersized perimeter expansion space
NWFA calls for expansion space at every vertical obstruction so the floor can expand and contract. That means walls, cabinet bases, door casings, stair stringers, fireplace hearths and pipes. Floors butted tight to a wall, a tile edge or a door jamb have no room to grow. The gap size for vinyl plank is set by each plank maker's installation instructions, so check the sheet for your product.
Heat from sun through glass
Vinyl grows when it warms. A lane of floor in front of a west-facing slider or a large south window can get much hotter than the shaded floor a few feet away. ASTM F2199 is the lab test for how resilient tile and plank hold their size and resist curling after heat exposure. Its stated purpose is to simulate long service at reasonable and expected temperatures. A product that passes it can still expand while it is hot. When that daily swing meets a pinned edge or a tight perimeter, the hot zone is where the floor lifts first.
Long runs without a transition
The bigger the floating area, the more total movement it has to absorb at its edges. NWFA's floating-floor guidance calls for an expansion transition at doorways narrower than 4 feet and in any floating field wider than 20 feet or longer than 40 feet, unless the manufacturer directs otherwise. Vinyl plank makers set their own run-length limits. A whole-house run with no transitions, flowing through narrow doorways, often buckles at a doorway first, where the floor is squeezed.
Moisture coming up through a concrete slab
The Resilient Floor Covering Institute's moisture guide lists shifting, peaking or curling of modular planks and tiles among the problems excess slab moisture can cause. It also says moisture moving through a slab can change through the year, and that concrete of every age and grade level should be tested before resilient flooring goes down. A plank's waterproof surface does not stop vapor from collecting under it. That moisture can affect the underlayment or let the floor shift.
An uneven subfloor
Humps and dips force planks to flex at the joints, and a stressed joint is where a peak starts. NWFA's floating-floor flatness tolerance is 1/8 inch in 6 feet or 3/16 inch in 10 feet unless the manufacturer specifies otherwise. ASTM F710 covers preparing concrete to receive resilient flooring. ASTM F3261 notes that the attached backing on rigid-core planks helps with minor subfloor irregularities. Minor is the key word: the backing does not make up for a real hump or dip.
What You Can Check
- Start with what sits on the floor. If kitchen cabinets, an island, built-ins or a heavy appliance stand on top of the planks rather than the planks stopping at them, the floor is pinned. A peak that runs away from that spot is a strong sign that the pin is the cause.
- Pull a short length of quarter-round or base shoe at the wall nearest the peak. Look for a gap between the flooring and the wall, and check whether the trim nails go down into the planks. Do the same at door jambs, transitions and stair noses: any trim screwed or nailed through the floor is a pin.
- Note when and where it happens. A ridge that rises on hot afternoons in front of a slider or big window and relaxes overnight points to heat. A hump at a narrow doorway in a long run points to too little room to move. A floor over slab that has trouble mainly in one area, or that smells musty, points toward moisture.
- Lay a long straightedge or level across the floor near the peak. If it rocks on a hump or bridges a dip, the subfloor is out of flat. Press on the planks along the ridge: one that clicks, shifts or has a lifted edge may have a damaged locking joint.
- On slab-on-grade homes, have the concrete tested for moisture before anything is reinstalled. RFCI notes that a test only shows the condition of the area tested at the time it was run. A pro may test more than one spot and lift a plank to check the underside and the underlayment for dampness.
Can It Be Saved? Repair vs. Replace
If the floor is pinned or tight at the walls and the planks are not damaged, the fix is to free it. That means cutting the flooring back at the walls and fixed objects to restore expansion space, removing nails or screws that pass through the planks, and re-anchoring transitions to the subfloor. A peak often settles once the pressure is gone.
When cabinets or an island were set on top of a floating floor, there is no small fix that keeps them there. Either the flooring is cut free around the cabinet base with expansion space left, or the floor in that area is relaid so it stops at the cabinets, which is what NWFA's guidance calls for.
If peaks or humps stay after the floor is freed, the planks in that area can be taken up and relaid. Planks with chipped, cracked or stretched locking edges should be replaced, because a damaged lock will not hold flat. Saved boxes from the original install make for an exact match.
If slab moisture is behind it, the moisture has to be measured and dealt with before the floor goes back down. That can mean a manufacturer-approved moisture barrier or a different product, depending on the readings and the plank maker's limits. Relaying over the same wet slab brings the same problem back.
Replacing a larger area makes more sense when buckling covers much of the room, when many locks are damaged, or when the subfloor has to be flattened under most of the floor. The new install should fix the cause: proper expansion space, transitions where the runs and doorways call for them, a flat subfloor and a slab moisture test.
Prevention
How to Prevent Vinyl Plank Buckling
- Install cabinets and kitchen islands first and run the floating floor up to them with expansion space, never under them. Keep very heavy items in mind when you choose a floating floor for a room.
- Leave the plank maker's specified expansion space at every wall and fixed object. Fasten baseboard and quarter-round to the wall, not the floor, and anchor transitions to the subfloor only.
- Follow the manufacturer's limits on run length and add transitions at narrow doorways and long runs, instead of floating one continuous sheet through the whole house.
- Cut down solar heat on floors in front of west- and south-facing glass with shades, blinds or window film, especially in rooms that get hard afternoon sun.
- On a slab, test the concrete for moisture before installing, using the method the plank maker requires (often ASTM F2170 in-situ relative humidity). Use the vapor retarder or underlayment the manufacturer calls for, and check that the subfloor meets its flatness tolerance.
Sources
- NWFA Installation Guidelines — Installation Methods: Floating (expansion space, transitions at doorways under 4 ft and spans over 20/40 ft, trim never fastened through, islands and 600-lb point loads, flatness 1/8 in. in 6 ft)
- Resilient Floor Covering Institute — Moisture Mitigation: Installation Considerations for Resilient Floor Covering (peaking of modular planks, slab testing, floating-floor moisture options)
- ASTM F2199 — Dimensional Stability and Curling Properties of Resilient Flooring after Exposure to Heat (scope)
- ASTM F3261 — Resilient Flooring in Modular Format with Rigid Polymeric Core (scope: attached backer and minor subfloor irregularities)
- ASTM F710 — Preparing Concrete Floors to Receive Resilient Flooring (scope)
- ASTM F2170 — Determining Relative Humidity in Concrete Floor Slabs Using in situ Probes (scope)
- Resilient Floor Covering Institute — Flooring Types (LVT/LVP and rigid core definitions)
Good to Know
Frequently Asked Questions
Will a buckled vinyl plank floor flatten out on its own?
Sometimes, if the cause is temporary, like an unusually hot spell, and the floor still has its expansion space. If the floor is pinned by cabinets, nailed trim or a screwed-down transition, it usually keeps buckling until the pin is removed. Once the floor can move freely, many peaks settle back down. If a peak is still there after that, the planks in that area need to be relaid.
Can I just glue or nail down the peaked planks?
No. A floating floor is designed to move, and buckling means it is already pushing against something. Glue, nails or weights lock that pressure in, so the floor lifts at the next weak seam or cracks a locking joint. The lasting fix is to free the floor and give it the expansion space it needs.
Why is my LVP buckling by the sliding door?
That spot gets the most direct sun, so the floor there heats and expands more than the rest of the room. If the floor is tight at the walls or pinned somewhere else, the hot zone is where it lifts first. Sliders also sit at a threshold where the floor is often cut tight to the track or trapped under a transition. Check both, then cut down the afternoon sun with shades or window film.
My vinyl plank is waterproof. How can moisture make it buckle?
Waterproof describes the plank's surface, not what happens beneath it. The Resilient Floor Covering Institute lists shifting, peaking and curling of planks and tiles among the problems excess moisture from a concrete slab can cause. Vapor coming through the slab can collect under the floor and affect the underlayment. That is why slab moisture testing comes before installation, waterproof plank or not.
Were my cabinets installed on top of the floor? Is that a problem?
With a floating vinyl plank floor, yes, it is a common cause of buckling. The NWFA guidelines for floating floors call fixed cabinetry such as kitchen islands a fixed vertical obstruction that locks the floor down. With the cabinet holding one area still, the rest of the floor's movement has to go somewhere, and it often goes up. The fix is to cut the flooring free around the cabinets with expansion space, or relay that area so it stops at the cabinets.
Is Sacramento-area heat a factor?
It can be. Long, hot summers and lots of west-facing glass put a big daily heat swing on floors in sun lanes. Many local homes are slab-on-grade, which adds slab moisture as a possible cause. Heat alone rarely buckles a floor that has proper expansion space and nothing pinning it. When a floor does buckle, the fix is usually about expansion space, pins and moisture rather than the weather.
Where to go from here
If you are weighing options, the next read is repair, refinish, or replace. When it is about your own floor, see luxury vinyl plank or skip ahead: a free in-home estimate means Alex measures the rooms, checks the subfloor, and quotes the exact product — no planning ranges.
Local pages for luxury vinyl plank: Auburn, Folsom, Roseville, Santa Rosa, Sacramento, Oakland, San Rafael and San Jose.
Diagnosis written by
Owner & Lead Installer, Renaissance Floors
15+ years of hands-on flooring experience across Greater Sacramento & Northern California. Works on hardwood and engineered installation, refinishing, subfloor preparation, and moisture testing — and writes these guides from what the jobs actually teach.
Licensed California contractor, CSLB C-15 license #1060673(verify ↗)
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Related pages: Flooring Problems, American Walnut, Wide-Plank Flooring, and Rift & Quarter-Sawn Oak.
Think You Have Vinyl Plank Buckling?
We'll inspect your floor, find the moisture or structural source, and tell you honestly whether it's a repair or a replacement. Call (916) 749-0272 for an assessment.