Cupping

Description
This usually develops slowly, with the floor 'cupping' upwards at the outer edges across the width of the plank - resulting in the edges being higher than the centre of the wood flooring board. If not addressed, this can develop into the more serious problem of buckling.

Possible causes
Assuming that the material was manufactured as a flat floorboard and installed flat, the most likely cause is a variation of moisture content within the wooden floorboard itself. This causes expansion at the outer edge because the moisture level is greater on the bottom of the floorboard than on the top. In other words, it is drier on top where the floor is directly exposed to the atmosphere, and wetter on the bottom where the floor comes into contact with the sub floor.

Sometimes cupping can be caused by humidity in the room, which can be corrected with a humidifier. A source of moisture in the sub floor, which needs to be investigated and eradicated, is another possible cause.

Expansion in the floor due to moisture causing a tightening across the width of the floor can lead to similar problems.

Remedial tips
If the floor is tight to a wall or skirting or door frame, the pressure should be alleviated where necessary. Sometimes simply allowing time after removing moisture, and for the benefits of remedial works to take effect, will lead to the flooring settling down.

If this is not the case, once you are satisfied the moisture problems are cured and that the floor has been fitted with appropriate expansion, it may be necessary to sand it flat and refinish.

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