It is common to see gaps show up in wood flooring during the winter time. As the temperature goes down and the need to warm our home increases, the relative humidity (RH) in our home lowers. With decreased RH, the moisture content in our hardwood floors is reduced causing the flooring to shrink.
Industry standards as well as most wood flooring manufacturers recommend a temperature range between 60° and 80° and a relative humidity range between 35% and 55%. So to be safe, start in the middle of these recommendations and aim for 70° and 45% RH. If you could keep your home at these rates constantly, your wood flooring would not move – a tall order for sure! If the temperature and relative humidity swing no more than 10%, the wood floor will move very little and still be within an acceptable range. When allowed to get outside of the recommended range, the flooring will tend to shrink at a greater rate, showing larger gaps in the dry winter months.
Remember the wider the flooring product, the larger the gaps. The narrower the boards, the gaps will be smaller.
There are many areas of the country where the winter temperatures dip below freezing. In these areas you will need to add additional humidity via a furnace mounted whole home humidifier unit. If the system is installed, tested, and operating correctly, you will be more likely to keep the humidity levels within the recommended range. Without a whole home humidifier or several smaller capacity room size units, you are sure to see larger gaps develop and grow throughout the heating season.
As we roll into late spring and the hot summer, the humidity will start to rise and the gaps slowly close up. When this occurs, it is considered an acceptable normal gap. If the gapping remains throughout the summer cooling season, there may be a need for a flooring professional or NWFA inspector to take a closer look at what might be going on.
There are many reasons why natural hardwood floors are chosen over other floor coverings like carpet and tile. Its natural beauty and warmth connects the homeowner organically to the land and a centuries old trade. Being educated about how to care for this natural product will make you and your floor happier.
With nearly 40 years in the industry as installer, inspector, trainer, and adviser, Tim is the go-to guy for all questions about wood flooring. He has multiple certifications from the NWFA, countless industry achievements, and the insight of running a flooring business. He is now technical adviser for The Master’s Craft.