How Does Humidity Affect Your Wood Floors?
Wood is a natural product that responds to its environment. During winter months when heating systems are running, wood floors will shrink, resulting in gaps between floorboards. When humidity is higher in the summer, wood floors swell. This is a normal reaction that occurs from season to season, but it can be minimized by keeping your home between 60-80 degrees Fahrenheit and 30-50 percent humidity all year.
Humidity and temperature controls will have the biggest impact on the life of your floor. During winter months when heating systems are running, wood floors will shrink, which can result in gaps between floorboards. When humidity is higher in the summer, wood floors swell. This is a normal reaction that occurs from season to season, maintaining a consistent temperature (60-80 degrees Fahrenheit) and humidity (30-50 percent) year-round will minimize any noticeable swelling or shrinking.
— NATIONAL WOOD FLOORING ASSOCIATION. Homeowner’s Handbook to Real Wood Floors