There are woods out there, both common species and exotic, that do not grow fast enough to be considered a rapidly renewable resource. But they can still be sustainable if the fall into one of two categories. If the woods are "certified, " the harvesting practices that the timber companies and mills use to produce product have been inspected by a third party to find out if the guidelines that party adheres to ensure no forest depletion and minimal disruption are being met. There are several certification organizations but the most respected, and the one endorsed most by environmentalists, is the Forest Stewardship Council or FSC. It is the organization that has the most stringent requirements for what they consider sustainable enough practices to achieve their approval and it is also the organization that is looked upon as most impartial and truly environmentally oriented. FSC or other certified wood products will not look or be any different than the same wood species in their non-sustainable form, so if there is a wood that has a great look or matches a design nicely it will be the same wood in an FSC certified form, only harvested with certain practices. "Reclaimed" means that the material you are using for flooring was milled and used in some application previous to its use in its current or future flooring project. It is true recycling of the material and usually has loads of character (i. e. big knots or cracks, nail holes, wear and staining, etc. ) and a lot of times has a story behind it. Some fairly common sources of reclaimed material include old barns, fences, old city factories that are being torn down, etc. Either one of these two options allows a house or a commercial project lots more choice when it comes to being environmentally friendly with their wood choices, as well as a beautiful floor to add ambiance and maybe even start some conversations. Source: Sustainable Flooring
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http://sustainableflooring.com/blog/what-do-the-terms-%e2%80%9ccertified%e2%80%9d-and-%e2%80%9creclaimed%e2%80%9d-mean