Laminate flooring lifting? Why floors peak or buckle and how to get them flat

A lifting laminate floor means one of two things: the floor has expanded with nowhere to go, so it is pushing itself up at the joints, or the boards have swollen with moisture and changed shape. The first is called peaking, and it is fixable in an afternoon by giving the floor back its room to move. The second means finding the water, then replacing the boards it reached, because a swollen fibreboard core never shrinks back flat. Telling the two apart takes a minute and decides everything that follows, so start there before moving a single board.

Why is my laminate floor lifting?

Laminate floats as one connected raft, and the raft grows and shrinks with the seasons. Across a 5 m (about 16 ft) room the seasonal movement is several millimetres, which is exactly what the 8 to 12 mm (about 5/16 to 1/2 in) expansion gap around the edge is for. When the gap is missing, or something pins the raft to the subfloor, the expanding floor meets an immovable object and the only direction left is up. Match what you can see to the cause:

The first three share one root: the floor is trapped. Number 2 on the list of laminate mistakes covers how floors end up that way, and the last row of the table is a different problem wearing a similar disguise, dealt with in the uneven floor guide.

Is it peaking or water damage?

Everything about the fix hangs on this, and your hand can tell faster than your eye. Run it across the raised area:

• Peaking feels like a tent. The boards are still flat and hard, and they meet at a sharp raised line along a joint. Push down on the ridge and it gives slightly, because the boards are under tension, not deformed. Peaks also move with the weather, higher on warm humid days.
• Swelling feels like a blister. The rise is in the boards themselves: edges lifted into soft rounded ridges, a surface gone wavy, corners that feel spongy under a thumbnail. Swollen edges stay swollen in every season, because the fibreboard core has taken up water and grown.
• Location is the second clue. Peaks appear along joints, anywhere the floor happens to relieve its tension. Swelling clusters around its water source: a dishwasher, a radiator valve, an exterior door, or spread evenly across a room over a damp concrete slab.

A floor can have both at once, a trapped raft and a leak, but each still gets its own fix. Free the floor for the peaks, and hunt the water for the swelling.

How do you fix a laminate floor that is peaking?

By giving it back the room it was supposed to have. The tension in a peaked floor is real, and the moment you release it the boards want to lie down again:

1. Open up the nearest edge. Lift or unclip the skirting or beading on the wall closest to the peak and look at the gap between the boards and the wall. You are looking for the place it has closed to nothing.
2. Trim the gap back open. Where the boards touch the wall, cut them back with a multi-tool, or a sharp chisel where a tool will not reach, until roughly 10 mm (about 3/8 in) is clear along the whole edge. The trim covers the cut afterwards.
3. Free every pin. Unscrew any threshold bar fixed through the boards and refix it to the subfloor only, pull nails holding beading down through the floor, and loosen pipe collars clamped tight. The expansion gap guide lists the usual suspects, and doorways hide most of them.
4. Weight the peaks overnight. Boxes of books or a stack of unopened flooring packs on a towel, left for a day, settle the released joints back level.
5. Re-check in a week. A floor that peaked once had months of pressure on those joints. If a ridge returns with no pin left anywhere, the joint is damaged, and that board is a replacement job rather than a mystery.

The same trapped-raft physics can pull a floor apart instead of pushing it up, which is why a floor that peaks in summer often opens gaps in winter: one cause, two seasons. And if the floor peaked within weeks of being laid, the boards probably went down straight off the van; the acclimatisation guide explains that first-season surprise.

What if the boards have swollen with water?

Then flattening is off the table, and the job is to stop the water and replace what it ruined. Swollen fibreboard is a one-way change, so work in this order:

1. Find the source before touching the floor. Obvious candidates first: dishwasher and washing machine hoses, radiator valves, a door where rain blows in, plant pots, steam mops and wet mopping. The last two surprise people: cleaning is the most common way water gets onto a laminate floor, and standing water finds the joints in minutes.
2. Suspect the slab if the swelling is everywhere. Uniform edge swell across a whole ground floor room points below: a concrete subfloor passing moisture up into the boards, usually a missing damp proof membrane or a screed that never dried. The laying laminate on concrete guide covers the moisture tests, and this failure means lifting the floor and fixing the membrane, not swapping boards.
3. Replace the swollen boards. A click floor disassembles: take the skirting off the nearest wall, unclick rows back to the damage, swap the boards, and relay the same ones on the way back. Spares from the original batch make this painless, which is one more argument for buying right the first time, since a top-up pack from a new batch rarely matches.
4. Dry everything before it closes up. Underlay and subfloor need to be properly dry before the boards go back, or the new boards inherit the old problem.

How do you stop laminate lifting again?

Every cause on this page is a fitting decision, which is good news: they are all cheap to get right and all checkable before the first cut.

• 8 to 12 mm of expansion gap on every side, including doorways, pipes and around fixed furniture, with spacers doing the measuring during the lay.
• Nothing fixed through the boards, ever. Skirting to the wall, threshold bars to the subfloor, kitchen units on the subfloor with the floor stopping at the plinth.
• 48 hours of acclimatisation flat in the room before laying, so the boards do their expanding before they are locked together.
• A break at a doorway before a run reaches about 10 m (about 33 ft), since past that the gaps cannot absorb the movement; the transitions guide covers where to break and what covers the joint.
• Damp cloth, never a wet mop, and spills wiped when they happen.

All but the mopping live in the layout plan. The laminate calculator turns your room into whole packs with a sensible spare margin, and the layout planner draws the full floor with the expansion gaps and doorway breaks already in place, so the raft you lay has its room to move from day one. A laminate floor that never gets trapped and never gets wet stays exactly where you clicked it.