Use naturally rot-resistant wood outside

Naturally rot-resistant wood is a good alternative to lumber treated with chemical preservatives.
Redwood, western cedar, cypress, black locust, Pacific yew, and ipe, a South American hardwood, are good options. Choose lumber that is either salvaged or certified from a well-managed forest according to the standards of the Forest Stewardship Council(FSC) Nonprofit organization that promotes forestry practices that are sustainable from environmental and social standpoints; FSC certification on a wood product is an indicator that the wood came from a well-managed forest.. Remember that only the heartwood, not the sapwood, of these species are rot resistant.

Green Points

LEED for HomesLeadership in Energy and Environmental Design. LEED for Homes is the residential green building program from the United States Green Building Council (USGBC). While this program is primarily designed for and applicable to new home projects, major gut rehabs can qualify. : 1/2 point for using FSCNonprofit organization that promotes forestry practices that are sustainable from environmental and social standpoints; FSC certification on a wood product is an indicator that the wood came from a well-managed forest.-certified decking (MR 2.2). As a prerequisite, FSCForest Stewardship Council. An independent, nonprofit organization that promotes responsible forest management through the use of a third-party certification process. FSC certification includes a chain-of-custody requirement that tracks sustainability of wood products from growth to end use.-certification is required when tropical wood is specified.
NGBSNational Green Building Standard Based on the NAHB Model Green Home Building Guidelines and passed through ANSI. This standard can be applied to both new homes, remodeling projects, and additions. /ICC-700: Up to 4 points for using certified wood products (606.2).

Learn more in the Green Building Encyclopedia:

DECKS AND PORCHES
DECKING