Information provided directly by GRANORTE.
Cork, as a wood product, has some characteristics similar to hardwoods in that it expands and contracts with changes in temp & humidity. Thats why its so important to acclimate the product in your home.
Just like other wood products, cork is subject to the phenomenon of expansion and shrinking in response to climactic changes. Extreme environmental conditions, meaning exposure to extreme heat, moisture or dryness (more than 65%, less than 35% R.H) can cause cork to shrink and make joints more visible.
When humidity levels are higher, cork flooring can expand. As a general rule, cork flooring is more stable than wood flooring. When wood expands, it does so only across the grain, so the expansion is concentrated in one dimension. However with cork, any expansion or shrinkage is dispersed in all directions. With proper acclimation, installation, and maintenance, expansion and shrinkage of your cork floor will be less noticeable.