Wood Flooring: Narrowing the Gaps

My new hardwood floor has developed gaps! What went wrong?

This is a common concern in the winter as the home humidity’s plummet and gaps begin to form between the wood boards. While it may be alarming to first-time hardwood flooring owners, even the most carefully installed wood floors dry out and shrink. So what’s going on and what can we do about it?

Why Gaps Develop in Wood Floors
As cool weather moves in, high summer humidity diminishes and you begin to use your furnace. This causes the humidity in your house to drop. Summer humidity is typically around 50% relative humidity, but can get as high as 80-90%. However, in winter months the humidity in your home is in the 30-35% range, but can drop as low as 20%.

How to Diminish Gaps in Wood Floors

  • Wood species and board width: Narrow width boards shrink less that wide boards. A 5″ wide plank will shrink twice as much as a 2 1/4″ plank. Some species are also more stable than others. Hickory shrinks more than oak, followed by birch, white ash, black walnut and then pine.
  • Control House Moisture: The other approach is to address the moisture issue in your house. Using air conditioning in the summer and humidifying your home in the winter will help. A good annual range for the best wood flooring performance is a swing of 20&% RH from summer to winter. Think 50% in the summer and 30% in the winter as good targets for average relative humidity for your home. Humidifying in the winter can be done with a stand-alone humidifier or with one attached to your forced air furnace.
  • Enjoy the Wood Character: Another solution is simply to accept some gaps. Wood will be wood and the laws of physics always rule. Gaps will form in the winter and close in the summer. If small gaps are acceptable, doing nothing may work for you, especially if you realize that they will disappear. If even hairline gaps are unacceptable, you will need to address controlling your humidity within a tighter range.

Questions? Give us a call at Enterprise Wood Products 715-369-5700 and we’ll be happy to help you out!