Wood is an organic material that reacts to its environment. In humid environments, wood gains moisture and can swell. In dry environments, wood loses moisture and can shrink. If the environment in which your wood floors are installed changes drastically, it can cause changes in your floors and the way they perform.
If your floors gain moisture, they can cup. Cupping occurs across the width of the floorboard, with edges that are raised on each board and centers that are lower than the edges. If your floors lose moisture, they can gap or split. This can occur between floorboards or on the face of the boards. Gaps and splits can vary in size and are considered to be normal if they appear and disappear during normal seasonal changes. If the gaps in your floors are large or do not close during more-humid months, it’s time to call a professional.
Both of these issues can be minimized by keeping your home between 60-80 degrees Fahrenheit, and between 30-50 percent humidity, year-round.
A complete sand and refinish is recommended when there is damage to the wood floor like deep scratches, dents, and other flooring damage. It is also recommended when the finish has worn away, and the bare wood is exposed. Sanding a floor back
The number of times a floor can be sanded varies depending on a variety of factors including the skill of the contractor, the equipment used, the thickness of the wear layer, the flatness of the floor and the condition of the floor.