Decks are a great way to enjoy the fresh air and our gentle climate. However, demand for common decking materials such as redwood, cedar, and some hardwoods has a significant impact on our forest resources. Incorporating environmentally preferable decking, railing, and fencing materials in your project can reduce habitat destruction, waste, pollution, energy use, and can mean a lasting, low- or even zero-maintenance finished product. Consider:

• Repairing and/or refinishing existing decks, railing, or fencing
• Reusing wood in good condition (See the Monterey Bay Area Green Building Directory for sources).
• Durable materials such as plastic lumber made of recycled plastic and waste wood.
• For structural elements that will be in contact with soil and water, consider:
  • Relatively new plastic/wood/fiberglass composite lumber, which is structural.
  • Heartwood from decay-resistant species such as redwood or cedar which has been FSC Certified as harvested from a responsibly managed forest.
  • If you choose pressure-treated lumber, the two water-resistant preservatives in current use (C-A and ACQ) are significantly less toxic than CCA.
  • Avoid the few remaining stocks of CCA. (CCA production for residential use ceased in 2003.)

The extraction, manufacture, transport, and disposal of timber pollutes air and water, depletes resources, and damages natural habitats. Some of the most decay-resistant trees (for example, redwoods) require decades to centuries to mature. Old growth forests develop their biodiversity over millennia; remaining old-growth stands should be preserved for the benefit of all. Plastic lumber helps reduce solid waste, reduces impacts from harvest or mining of virgin materials, with greater durability and low- to no-maintenance.

Pressure treated lumber has been popular for decades for its resistance to rot and insects. The familiar copper chromated arsenate (CCA) was largely phased out in a cooperative effort between manufacturers the US Environmental Protection Agency. Production for residential use ceased at the end of 2003, with the caveat that existing stocks would still be sold. Some CCA treated material is still available, partly due to remnant inventory and in part because consumers can purchase non-residential products. CCA was phased out because arsenic is acutely toxic and carcinogenic, and was shown to be leaching into surrounding soils.

Existing CCA-treated lumber poses a challenge. It remains resistant to rot and insects, and its reuse would help conserve forest resources and keep a potentially useful resource out of landfills. However, it would also continue to leach arsenic into soils if reused. CCA-treated wood should not be composted, or disposed of in green waste or wood waste bins. Burning CCA-treated wood is highly toxic, a very bad idea. Disposal is unfortunately the most appropriate fate for this material. Effective January 1, 2005, AB 1353 requires treated wood waste to be disposed of either in a lined landfill or as class I hazardous waste.

Note that the newer, much less toxic wood treatments (C-A: Copper Azole and ACQ: Alkaline Copper Quaternary) are more corrosive than CCA; use manufacturer-recommended fasteners to minimize rust and prevent staining