Cork, harvested from quickly replenishing cork tree bark, comes in planks and tiles for flooring. Cork flooring typically does not contain toxic formaldehyde, but some types require glue. If needed, ask for the healthiest type of adhesive.
Look for moisture-resistant products. Not all are designed to prevent moisture from penetrating. Compare warranties.
Cork is competitive with wood flooring, at about $10/SF versus $9 for oak strip flooring.
Dan Chiras, Ph.D., author of this article, is Director of The Evergreen Institute and President of the consulting firm, Sustainable Systems Design, Inc. Dan is the author of Green Home Improvement and 23 other books on green building, residential renewable energy, and sustainability.