If your new laminate or vinyl plank has lifted at the edges or peaked in the middle of the room, the cause is almost always the same: the floor had nowhere to move. This guide shows how to set expansion gaps correctly so a floating floor stays flat through Newcastle’s damp coastal winters and dry, centrally heated rooms. You will learn why floors move, how much gap to leave, where installers get it wrong, and how to fix a floor that has already failed.

Why floating floors move at all

A floating floor is not glued or nailed down. The planks click together and sit on the subfloor as one continuous raft, held only by their own weight and the skirting around the edge. That raft changes size. Wood-based cores and vinyl both expand when they take on moisture or heat, and shrink when the air dries out. In a coastal climate like Newcastle’s, indoor humidity can swing widely between a wet winter and a heated living room, so the raft is constantly growing and shrinking by small amounts.

If the raft can move freely, you never notice. If the edges are pinned, all that pressure has to go somewhere. It pushes up into a ridge (buckling or peaking), or it tears the joints apart when the floor shrinks (gapping).

It works in both directions

People fixate on buckling, but under-sized gaps also cause the opposite problem. When a trapped floor later dries and contracts, the locked edges hold it, and the joints in the field of the room split open instead. Both symptoms trace back to the same root cause: no room to move.

How much gap to leave

The real authority here is the installation sheet in the box. Manufacturers specify their own perimeter gap because it depends on the product’s core and format, and installing outside those instructions can void the warranty. As a general pattern, most rigid laminate and LVT products call for a continuous gap of roughly a centimetre around the whole perimeter, with larger rooms needing more. Treat any number you read online, including this one, as a sanity check, not a substitute for the printed spec.

A practical rule: the longer the run, the more it moves. A small hallway needs little. A large open-plan living and dining space needs the full gap and often a transition strip partway through.

The spots people forget

• Doorways. Do not run one continuous floor from room to room through a doorway. Break it with a T-molding so each room can move on its own.
• Pipes and radiator legs. Drill the hole oversized and cover it with a pipe collar, never a tight fit.
• Kitchen islands and heavy units. A floating floor should run under them only if it can still slide. Better practice is to fit units first and float up to them, so their weight does not pin the raft.
• Large rooms. Beyond the manufacturer’s stated maximum run, you need an expansion joint in the middle, not just at the walls.

A real scenario

A common call-out: a terraced house living room where laminate ridged up along the wall under the window within a few months. The installer had left a gap, but then run a bead of silicone between the floor and the skirting to “finish it neatly.” The silicone glued the edge solid. The floor expanded in the humid months, could not slide under the skirting, and lifted. The fix was to cut the silicone out, trim the plank edges back to restore the gap, and let the ridge settle flat over a week. No planks needed replacing, but a scotia bead pinned to the wall would have prevented the whole thing.

Common mistakes and how to fix them

• Skirting or scotia nailed down into the floor. It must fix to the wall only, sitting lightly on top of the planks. Re-fix into the wall so the floor slides underneath.
• Silicone or adhesive sealing the perimeter. Remove it. Use a floating scotia or trim to hide the gap instead.
• Gap set correctly but then filled with off-cuts. Clear the gap out completely.
• One run carried through a doorway. Cut the floor at the threshold and fit a T-molding.
• Floor laid before acclimating the boxes to the room. Always let the product sit in the room first so it moves before, not after, install.

Action checklist

• Read the manufacturer’s gap and maximum-run figures before you start.
• Use spacers along every wall and around every fixed object.
• Keep the gap continuous, including behind radiators and door frames.
• Break the floor at doorways and beyond the maximum run.
• Oversize all pipe holes and use collars.
• Fix skirting and scotia to the wall, never to the floor.
• Never seal the edge with silicone or glue.

Conclusion and next step

Expansion gaps are the cheapest insurance in the whole job. Before your next install, walk the room and mark every wall, doorway, pipe, and heavy unit where the floor must be free to move. If you already have a buckled floor, check the perimeter first: nine times out of ten the gap is missing or blocked, and it is fixable without a full re-lay.

FAQ

Can I fix a buckled floor without lifting the whole thing?

Often yes. If the buckling is at the edge, free the perimeter (remove pinning skirting or silicone) and trim the plank edges to restore the gap. The ridge usually relaxes flat over days. Field buckling from a soaked core is different and may need board replacement.

Do vinyl planks need expansion gaps too?

Rigid click LVT does, because it still expands with heat. Follow the product’s sheet; the gap is often smaller than for laminate but it is rarely zero.

Why does my floor gap in winter and go tight in summer?

That is the raft shrinking in dry, heated air and swelling in humid air. Small seasonal movement is normal; large gaps that open every winter point to an under-sized perimeter gap that traps the floor and forces the joints to split instead.

Does underfloor heating change the gap?

Yes. Heated floors move more, so manufacturers who approve their product for underfloor heating usually specify a larger gap and a controlled warm-up schedule. Check the sheet.

References

• Manufacturer installation instructions supplied with each flooring product (the binding source for gap size, maximum run, and warranty terms).
• British Standard BS 8203, Code of practice for installation of resilient floor coverings.