Alternatives to Pressure Treated Wood (Outdoor Lumber)

September 28, 2011 Three comments View all articles in General

Bet you didn't know lumber intended for outdoor use, also known as pressure-treated wood, was – until recently – treated with chromium, copper, and arsenic (chromated copper arsenate, or CCA). Pressure-treated wood is poisonous to insects, fungus, and bacteria, as well as humans and pets. In fact, California and most other states list CCA-treated wood as a carcinogen. Its toxic ingredients leach quite readily into surrounding soil, especially sandy soil, which is why so many towns have been ripping out playground sets built with this kind of wood. Flower beds and vegetable gardens framed with CCA-covered, pressure-treated wood are also at risk for toxin leaching.

Alternatives to pressure-treated woods are readily available, but discretion is still necessary when shopping for outdoor lumber. For example, borate-treated wood is a less toxic choice, but it's not suggested for use near soil.


  • One of the best choices for decks, fences, or any outdoor building project that will touch soil – especially aboveground gardens or sandboxes – is local cedar. No sealants or chemical treatments are needed because cedar has so many natural oils and is naturally resistant.
  • Use reclaimed redwood or cedar, which can be found at some building material reuse centers, and then seal the lumber yourself with linseed oil.
  • Looking for a Forest Stewardship Council (FSC) label on whatever wood you choose will ensure that it has been sustainably harvested.
  • If you're redoing your deck, consider purchasing FSC-certified deck tiles made from fast-growing eucalyptus.
  • Recycled plastic is incredibly durable and rot- and corrosion-proof, which makes it a great decking and fencing material. Using 1.5 million recycled plastic grocery bags mixed with waste wood, Trex creates fencing, decking, rails, and benches, which are sold at your local Home Depot and Lowe's.
  • All-natural finishing oil or plant- and mineral-based wood treatments are healthier weather-proofing options than chromium and arsenic.
  • More natural, nontoxic-yet-heavy-duty wood sealants include SoyGuard Premium Water Repellant and Wood Sealer, Deck Boss, and LifeTime Wood Treatment.
  • If you want to replace any of your outdoor, pressure-treated lumber, contact your municipality for disposal instructions. You'll probably have to take the wood to your local hazardous-waste depot.

(photo by Viance)


Tim on Feb. 18, 2016 at 7:47 a.m.

Thank you for the info! One quick thing to note though: FSC lumber is NOT sustainable (nothing that involves burning fossil fuels is sustainable, like harvesting, processing, and delivering FSC lumber). Better to say, "...ensure that your selection is as sustainable as possible." FSC helps us with the unsustainability of deforestation, but there are other non-sustainable aspects to the use of lumber besides forest management. This correction will help our global community understand how much farther we must go before we are a responsible society. Thank you!

Roger Groot on Sept. 7, 2016 at 6:40 p.m.

I could not find the best to use on untreated wood,whether Linseed oil is as good as cedar oil?

JAY MANGCAL on Oct. 18, 2016 at 5:38 p.m.


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