Why Laminate Flooring Swells and What to Do

Laminate flooring usually swells after moisture reaches the board edges, when the floor has no room to expand, or when an uneven subfloor keeps loading the locking joints. First stop any source of water and identify whether the raised area is trapped at an edge, damaged in the middle, or affected by moisture below the floor.

What commonly causes a raised floor

• Water reached the joints, the subfloor or the board edges and the specific product could not tolerate that exposure.
• The floor is tight against a wall, threshold, pipe or fixed furniture and cannot move as temperature and humidity change.
• The subfloor has a dip or high point that keeps the boards and their joints under load.
• A locking joint was damaged during installation, moving furniture or a local leak.

How to narrow down the cause

Mark the affected area and inspect nearby walls, thresholds, pipes and joints. A musty smell, dark board edges or a distorted underlay suggest moisture. A ridge near the centre of a dry room can point to a blocked perimeter or subfloor movement. If water may have come from the structure or building services, resolve that source before opening the floor.

When a local repair may be enough

If the source of moisture has stopped and the boards and locking joints are still intact, remove only accessible trim where it is safe to inspect whether the floor is trapped. Once dry, reassess the area. Boards that have swollen through their core or delaminated generally need replacement with matching material, if it is available.

When the floor needs a wider inspection

A large wet area, persistent odour, movement in the subfloor or a suspected leak below the covering calls for a broader inspection. Replacing a few visible boards without drying the layers below can repeat the same problem and may trap moisture where it is difficult to see.