If the humidity goes above 55% (usually in the summer), reduce it by using a dehumidifier. Turning the air conditioning up/on will also help. Too much moisture can cause the floor to swell and the boards to warp or cup. This is true for both solid hardwood and engineered wood. While engineered tends to be more stable than solid, it is still susceptible to moisture, albeit less. Laminate can also warp, and vinyl plank can buckle.

If the humidity drops below 35% (usually in the winter), you need to raise the level. Low levels can cause the wood to dry out which causes gapping as it contracts, or it could lead the floor to split along the grain (known as checking). If you do need to raise the humidity level, try a humidifier to boost the overall moisture in the room. Newer homes have humidifiers attached to the furnace.

Use a hygrometer to check the humidity levels in rooms where you have wood or laminate. These are available from most home centers at little cost. Keep an eye on the hygrometer and if the humidity level falls much below 35% in the winter or above 55% in the summer, then you need to make adjustments as above.