Humidity and Hardwood Flooring
Colorado and the surrounding mountain states are among the most challenging regions for all wood products because of our extremely dry climate. The concerns of relative humidity control have been addressed by all major wood flooring manufacturers and are clearly documented by them and the National Wood Flooring Association. The following are important points to consider:
- It is the responsibility of the homeowner to keep the relative humidity within a constant and acceptable range. Consideration of an appropriate humidification system should be given when a home is designed, or when hardwood flooring is added to an existing home.
- Experts differ slightly on the range they feel is the most appropriate, but a consensus would be between 25% and 40% relative humidity. Any in-home environmental conditions at the low end of, or below, this range will probably result in drying and cracking to some extent of most woods. Without additional humidification, in-home relative humidity can drop below 20% during the heating season because our Colorado winters are so dry.
- Even if the atmosphere is generally controlled within this range, there will still be some movement as the seasons change and the relative humidity moves up or down.
- Wood is a natural product and its limits must be respected. Because extremely low humidity has such a profound effect on properly manufactured and installed wood flooring, manufacturers do not consider some plank separation or cracking to be defects that would be covered under their warranty.
- Engineered wood flooring is more stable than solid wood flooring and will not shrink or expand as much. However, it is still an all-wood product that will react to swings in humidity.
- Solid wood floors generally will expand and contract more than engineered floors resulting in larger gaps between the flooring boards during dry times of the year.
- Extremely dry conditions (those below 25%) will result in gaps between solid wood planks. The size of the gaps will depend upon the size of the planks. The wider the plank, the wider the gap.
- Extremely dry conditions (those below 25%) will also result in gaps between engineered planks. However, they will not be as wide. Extremely dry conditions may also result in cupping of engineered planks. (Dry cupping is caused when the top of the board is dryer than the bottom.)
- Extremely dry conditions (those below 25%) may also result in cracks and checking in the surface of both engineered and solid planks. These are not considered defects and are not covered under manufacturer’s warranties.