The photograph above may not be what you would expect.  The outdoor bench in this detail is not made from an unsustainably harvested tropical hardwood.  The wood itself is actually maple, a widely available species that can be farmed and harvested without ripping up acres of rainforest.  But maple and many other similar woods are too susceptible to decay and rot when used unprotected outdoors.  The usual alternative has been treatment with chemical pressure treatment.  Now, through a method called kebonization, a Norwegian company, Kebony ASA, treats soft woods in a non-toxic process that allows readily available woods to be used for outdoor uses.

The process of kebonization is similar to pressure treating wood (which is another way to make soft woods usable for exterior use). But, instead of soaking the wood in toxic chemicals like chromated copper arsenate (CCA, which is now banned for most uses in the US and the EU) or alkaline copper quaternary compounds (ACQ, the most widely used replacement for CCA after the ban), it is instead soaked in furfuryl alcohol, a waste byproduct from sugar cane. There are no special handling requirements or precautions needed to deal with waste from this wood, and it can be disposed of just like any other untreated wood.

During the kebonization process, the alcohol becomes a resin that reinforces the cells of the wood. The result is a wood with excellent outdoor exposure tolerance like teak or mahogany, but with a harder surface than many of the tropical woods that it replaces. The wood also naturally fades to a silvery-grey color much like those tropical woods, as well. Maple is used in place of teak, and southern yellow pine is used in place of ipe.

Kebony wood can also be used for building siding. In fact, it is so water and weather resistant that it is even been used for building roofs and for boat decking (see below). The process also makes the wood less prone to swelling due to moisture. There is no necessity to paint Kebony wood, and it can withstand decades of exposure to the weather before any maintenance is necessary. According to the company, a kebony wood roof can last for 30 years before any maintenance is required.

Kebony wood is probably not going to do much for you in terms of obtaining LEED credits.  The material is imported from Europe.  There is no indication on the company's website of the material being FSC certified wood, either.  Still, it is a natural wood product.  More importantly, it is a wood product that is durable without having toxic additives.  And it is obtained without clearcutting tropical rainforests.

Even more pictures are available on the Kebony website.

Photo credits: Kebony ASA.