Why does my floor have cracks/gaps in it?

In is common for cracks to appear in floors, especially with wider planks, due to shrinkage and expansion over the year. Small cracks are not harmful to the floor and most will only appear seasonally due to changes in moisture levels. In order to reduce or eliminated the chances of getting cracks in your floor, make an effort to maintain a humidity level between 45% and 55% throughout the year. Air conditioning or a de-humidifier in the humid summer months and a humidifier during drier seasons helps to keep the humidity level more stable year round.

Any article made of wood is subject to expansion and contraction resulting from changes in humidity. Wood is a hygroscopic material, which means it will absorb moisture in a wet environment and give off moisture in a dry environment until the wood reached equilibrium. Approximately 1% dimension change takes place with each 3% change in the moisture content of the wood. This applies to hardwoods more than soft woods. Maple is a hardwood, but is especially susceptible to this dimensional change relative to moisture content. Air can hold a certain amount of moisture at a given temperature. Relative humidity expresses what percentage of this maximum value that the air is actually holding. Warm air can hold more moisture than cool air. For example, if a sample of air at 32 degrees and 100% relative humidity is heated to 75 degrees, the relative humidity of that sample drops to 20% because the warmer air has a larger water holding capacity.

During the winter months, the interior relative humidity of homes drop significantly as the heat is turned on. Wood flooring (as well as wooden furniture and any other wooden objects) will shrink as a result of this decrease in relative humidity. This shrinkage will manifest itself in the form of slight cupping of the floor. These kinds of seasonal changes in wood flooring are normal, and are not defects. Seasonal changes in wood flooring can be mitigated through the use of climate control devices such as a humidifier.

Wood flooring should be stored in such a way as to minimize exposure to humidity levels greater than that of the normal level of the structure or residence in which it is to be installed. Wood flooring should be stored inside the enclosed structure or residence after heating and cooling systems are operational, near where the flooring is to be installed. Wood flooring must not be stored in a garage or other unheated structure, as the relative humidity in an unheated structure will be significantly different than that of the interior of the structure. Wood flooring must not be stored in a structure or residence where propane heaters are in use, as propane heaters generate large amounts of moisture as a by-product. Failure to follow proper storage procedures may result in expansion and contraction beyond the normal expansion and contraction described above.

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