The first step in building anything is choosing the right materials. If your project involves wood, you're going to have to decide between treated and untreated lumber. So what's the difference between the two? And at the end of the day, does it even matter? The short answer is yes, it matters -- especially if you happen to be building a playground set for your kids or a garden bed for your vegetables.
You might be surprised to learn that many forms of treated lumber can be harmful to your health. In the past, the treatment process involved filling wood with dangerous chemicals and chemical compounds like creosote, pentachlorophenol (PCP), and chromated copper arsenate (CCA) [source: Gegner]. None of these chemicals and chemical compounds are safe. In fact, the arsenate in CCA is a form of arsenic, which is a carcinogen known to cause many different types of cancer and even death [source: EPA].
Despite the dangers associated with arsenic, CCA treated lumber was the most common in the United States until manufacturers reached an agreement to stop producing it after 2003 [source: Williams]. Unfortunately, for many years, buildings and products were made using CCA treated lumber and they now pose health risks to those who come in regular contact with them.
While new techniques for treating lumber have been deemed safer, they still require precautionary measures. You'll find labels printed on treated wood warning those who are using it to wear masks and protect their skin [source: Austin]. It's also important not to let any type of treated wood come in contact with drinking water.
So if you want to know when it's better to use untreated lumber, the answer is almost always. The debate is still out on whether or not there are any instances in which using treated lumber can be considered completely safe but many builders still swear by its advantages.
Advantages of Untreated Lumber
The obvious advantage of using untreated lumber is that there are no health risks involved. It's as close to wood in its natural form as you're going to get without grabbing an axe and chopping down your own tree. If you're building anything that people will regularly be coming in contact with -- such as playground equipment, lawn furniture or benches -- you should always use untreated wood [source: Houlihan and Wiles].
Untreated lumber should also be used when you're dealing with gardening, whether you're building a raised garden bed, a flowerpot, or just making mulch. Some of the chemicals used to treat wood are meant to kill insects, which means they probably won't do wonders for your soil either. They can damage your flowers and make their way into your vegetable gardens -- ruining your prized tomatoes.
An obvious advantage of untreated lumber is its price; it's much cheaper than treated lumber. Since CCA-treated lumber was taken off the market, new treatment techniques use high levels of copper, which is more expensive. As a result, the cost of treated wood has risen considerably [source: Morrison].
When working with untreated wood, you don't have to worry about protecting your skin. You may want to wear a mask to keep from breathing in sawdust, but you can work in short sleeves and/or shorts without any fear of endangering yourself. The same can't be said for treated wood. In fact, when working with treated lumber, you should be adequately covered -- long sleeves, long pants and eye goggles are all a good idea. Afterward, make sure to clean any sawdust from you or your clothing thoroughly. And, of course, you want to avoid breathing in any sawdust particles from treated lumber [source: McClintock]. At a minimum, you should wear a dust mask/facemask while working with treated lumber. And, if you have one, a respirator would be even better.
At the end of the day, the ease of mind that comes with using untreated lumber may be worth it. You don't need to worry about potential health concerns, even if the wood comes in contact with your soil or water supply.
Advantages of Treated Lumber
Although there are health hazards to consider, treated wood does have its advantages. Treated wood was designed to defy the effects of natural aging. As wood is exposed to the natural elements, it slowly breaks down. Moisture is especially hard on wood. If treated, wood can last much longer than normal, but to make sure your treated lumber lasts as long as possible you need to match its treatment level with the right use. Lumber that is touching the ground, for instance, requires a higher treatment level than lumber that is not [source: Viance].
Treated lumber does have other advantages. Many types of treated wood are resistant to insects, like termites, that cause huge amounts of damage and cost home owners large sums of money. The chemicals used in the treatment process are toxic to insects, so any bug that tries to eat its way through a treated support beam will expire. On top of repelling bugs, treated lumber can also be fire retardant, taking longer to catch on fire and burning much more slowly when it does [source: WiseGeek].
In instances where treated lumber doesn't touch the ground and isn't exposed, it is relatively safe. You can also use certain oil finishes to protect treated wood and reduce the risk of it leaching dangerous chemicals during contact [source: Natural Handyman].
While treated wood has distinct advantages, you might decide that they aren't worth the added health risk. Yet, if you need something to last a long time and you know people won't come into much contact with it, treated lumber might be the better choice. In general, though, treated lumber shouldn't be used where untreated lumber will suffice.
The next time you're working on a project using wood, consider the advantages and disadvantages of both treated and untreated lumber before making a purchase.
For more information, check out the links on the next page.
Related HowStuffWorks Articles
- Austin, Gene. "Precautions still apply to treated wood." HighBeam Research. The Record (Bergen Country, NJ). May 13, 2004. (Accessed 02/22/2009)http://www.highbeam.com/doc/1P1-94521888.html
- Environmental Protection Agency. "Arsenic in Drinking Water." (Accessed 02/22/2009)http://www.epa.gov/safewater/arsenic/index.html
- Gegner, Lance E. "Organic Alternatives to Treated Lumber." ATTRA. (Accessed 02/22/2009)http://attra.ncat.org/attra-pub/lumber.html#intro
- Houlihan, Jane and Richard Wiles. "Poisoned Playgrounds: Arsenic in Pressure-treated Wood." Environmental Working Group. (Accessed 02/22/2009)http://www.ewg.org/reports/poisonedplaygrounds
- McCabe, John and David Wolfe. "Sunfood Living." Google Books. (Accessed 02/22/2009)http://books.google.com/books?id=wMSOfOuoaXgC&pg=PA6&lpg=PA6&dq=how+much+lumber+is+sold+around+the+world+every+year%3F&source=bl&ots=2yC8P2AgbP&sig=Faeg6D2dRAPKmYZa2CYJbvmANUQ&hl=en&ei=E2GjSYi5LYr2sAPa8sypAg&sa=X&oi=book_result&resnum=5&ct=result
- McClintock, Mike. "Pressure-Treated Lumber: The Debate Continues." HighBeam Research. The Washington Post. Feb. 7, 2002. (Accessed 02/22/2009)http://www.highbeam.com/doc/1P2-323620.html
- Morrison, Daniel S. "The New Pressure-Treated Wood." Fine Home Building. (Accessed 02/22/2009)http://www.taunton.com/finehomebuilding/how-to/articles/new-pressure-treated-wood-decks.aspx
- Natural Handy Man. "Pressure-Treated Wood - Its Uses, Limitations and Safety Considerations." (Accessed 02/22/2009)http://www.naturalhandyman.com/iip/infxtra/infpre.html
- Viance. "How long will treated wood last?" (Accessed 02/22/2009)http://www.viance.net/main/faqs.php#2
- Williams, Rose Marie. "Hazards of pressure treated wood. (Health Risks and Environmental Issues." HighBeam Research. Townsend Letter for Doctors and Patients. Aug. 1, 2003. (Accessed 02/22/2009)http://www.highbeam.com/doc/1G1-107201207.html
- WiseGeek. "What is Treated Lumber?" (Accessed 02/22/2009)http://www.wisegeek.com/what-is-treated-lumber.htm