Hardwood buckling or lifting off the subfloor

Boards no longer in contact with the subfloor — a raised ridge, a tented seam, or a whole section standing proud. It is unmistakable and you will usually hear it before you see it.

What causes it

In rough order of likelihood. Each one has a tell — the observation that separates it from the others.

1. 1

   A significant water event

   How to tell: A burst line, an appliance failure, a basement flood. Buckling within days of water arriving.

2. 2

   No expansion gap at the perimeter

   How to tell: The floor is tight to the wall under the baseboard with nowhere to grow. Buckles in the field or lifts at one wall in a humid spell. An installation failure.

3. 3

   Adhesive failure on a glue-down floor

   How to tell: Hollow-sounding areas nearby, and the lifted section moves as a unit.

What it actually means

The floor has run out of room or lost its bond. Unlike cupping, this rarely resolves on its own, and the affected boards have usually been stressed past recovery.

Where the cause was a one-off leak and the area is contained, the affected boards can be lifted out and replaced with matched material, then blended. Where the whole floor had no expansion gap, it is a re-lay. Insurance often covers the first case — document everything before anyone touches it.

• Stop the water. Everything else waits behind this.
• Photograph everything before any cleanup, from several angles, with something in frame for scale. Insurers ask.
• Lift area rugs and open the room up, but do not aim heaters at the boards.
• Do not screw or nail the lifted boards back down. It traps the moisture and guarantees replacement.

• Hardwood floor cupping — edges higher than the middle
• Hardwood floor crowning — middle higher than the edges
• Black or grey pet stains on hardwood