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.
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