Is Pressure Treated Wood Safe For Outdoor Furniture?

Outdoor Furniture

As summer starts to come into focus the thoughts of millions of Americans start to drift to their backyard, porch, or patio. Summertime fun in the sun, parties, and cookouts with the fam are what make summer so much fun! Of course, everyone will need a place to sit, relax, and eat, which means you’ll need some comfortable outdoor furniture. This leads to a very important question; Is Pressure Treated Wood Safe For Outdoor Furniture? If you’re the type who’s big into DIY projects, you might be wondering if pressure-treated wood is safe for you, your family, even your pets. Or does it contain harmful chemicals? It’s a good question, no doubt.

The good news is that, yes, pressure-treated wood is safe. Today’s pressure-treated wood manufacturers use chemicals in their process that are non-toxic and thus safe for humans and animals, at least when it comes to sitting and relaxing. That being said, let’s take a closer look at how pressure-treated wood is manufactured, what chemicals are being used, and anything that you shouldn’t be making with it.

What, Exactly, Is Pressure Treated Wood?

Like all natural substances, over time wood will begin to break down, rot and degrade. There’s very little that can stop this from happening at some point but, using a process called pressure treating, manufacturers can preserve wood so that it stays intact for a much longer amount of time.

The pressure treating process infuses wood with chemicals under great pressure. This helps prevent decay as well as repulse insects that love to eat wood. The process has been around for over 50 years, protecting wood and wood construction and saving consumers millions of dollars. One thing to note, however, is that pressure treated wood isn’t stronger than its non-treated counterpart. Pressure treating helps it to resists rotting and the elements but doesn’t increase its strength in any way.

What Type Of Wood is Best for Pressure Treating?

Soft wood like southern yellow pine is the most commonly used for pressure treating. That’s because it’s easier to force the chemicals into soft wood than it is into denser wood. The chemicals will be forced deeper into the wood fibers and thus give better, longer-lasting results.

What is the Difference Between “Above Grund Use” and “Ground Contact” Pressure Treated Wood?

When wood is pressure treated, as we’ve discussed, chemical preservatives are forced into its fibers so that rotting is prevented. The more chemicals that are used the longer rot, insect infestation, and decay will be put off. The highest concentration of chemicals will be labeled as ‘Ground Contact’ pressure treated wood. This means it can contact the ground and remain viable against, for example, water and the insects found in dirt and soil. This type of wood should be avoided for use in your outdoor furniture although, if the wood you’re using wasn’t manufactured using chromated arsenicals (CCA) it could still be used if needed.

Pressure treated wood that’s labeled as ‘Above Ground Use’ has a lower concentration of preservative chemicals and thus should be kept away from the ground so that it lasts as long as possible. Since it’s lower in chemicals using it for outdoor furniture is a better idea than using ‘ground contact’ wood.

How Long Will Outdoor Furniture Made Using Pressure Treated Wood Last?

This is a difficult question to answer with certainty only because the area of the country where the furniture will be used is such a big factor. For example, outdoor furniture in Phoenix, Arizona where it’s always hot and dry will likely last longer than the same furniture in Seattle, Washington where it rains for most of the year.

That being said, the average time that outdoor furniture will last if it’s been made with pressure treated wood is about 20 years. Depending on where you live, and the amount and type of severe weather your outdoor furniture experiences, you can add or subtract about 5 years from this number. Also, if you store your outdoor furniture inside during the winter months this will likely extend its life.

Which Wood Preservatives Have the Lowest Toxicity?

Several chemicals are used to pressure treat wood. The Environmental Protection Agency (EPA) of the United States is always conducting new tests on treated wood. In his way, they can make sure that these woods are safe for use in an environment where humans and animals will be in close proximity.

To that end, the EPA has approved several chemicals for use in pressure treated wood that can be used in human interactions. This is based on their low toxicity levels and includes:

You’ll notice that we listed ACQ (alkaline copper quaternary) first. The reason is that ACQ is the most preferred, and used, wood preservative in the industry. A water-based wood preservative, ACQ binds exceedingly well to wood fibers. This has the desired effect of making wood pressure treated with ACQ highly resistant to rotting, decay, and wood-eating insects. It even allows it to last longer when placed on or in the ground. Most importantly, ACQ is much less toxic than CCA and thus a far better choice for your outdoor furniture.

What is CCA and Why Is It a Problem for Use in Outdoor Furniture?

Chromated arsenicals are a group of pesticides that have been in use since the 1940s. They contain chemicals such as copper, arsenic, and chromium, which have long been shown to protect against fungi, termites, and other insects that destroy wood.

Among them is a chemical called chromated copper arsenate or CCA. After determining that it was hazardous to the health of humans and animals, manufacturers stopped using CCA in all wood products that were intended for use by homeowners. However, it has not been banned by the EPA and doesn’t need to be removed in exiting strictures.

The EPA determined that humans and animals can easily absorb CCA and that it can cause several different types of cancers. Even worse, CCA can leech out of wood that’s been treated with it, thus causing a health hazard. It’s for this reason that CCA treated wood should never be used for outdoor furniture. (No, you can’t buy it, but it can still be found in many structures and thus can often be found as ‘reclaimed’ wood.)

By the way, if you have a deck that was made using CCA you would be wise to remove it. At the very least, treating it with an oil-based wood stain as a protective coating will reduce CCA leeching.

Are There Good Alternatives to Pressure Treated Wood For Outdoor Furniture?

Yes indeed, there are several that will work quite well and provide long-lasting and beautiful outdoor furniture. They include;

  • Cypress
  • Redwood
  • Western Cedar
  • White Oak

What makes these woods so good for outdoor furniture is that, in their natural form, they already have properties that make them highly resistant to rotting, decay, and pesky insects. That’s because the heartwood, the inner part of the tree, is much more resistant to rot and insects that the sapwood, the outer part of the tree.

One caveat, of course, is that these woods are a bit more expensive than other wood (and pressure treated wood) because of their natural ability to not rot and to repel bugs. The good news is that you don’t need more than 1 picnic table, for example, or a few outdoor chairs. Once you’ve paid for them they will last for years, look amazing, and save you money since they won’t need to be replaced nearly as often.

What’s a Low-Cost Wood Alternative For Making Outdoor Furniture?

If you’re against using pressure treated wood due to the chemicals but don’t want to spend the extra money on naturally rot-resistant wood, pine is a fantastic alternative. It’s inexpensive, easy to work with, and looks good. It’s also easy to preserve so that it lasts longer.

The best way to do it is to apply several coats of a high-quality stain. After they dry completely, add another 2 to 3 coats of high-quality polyurethane. This will last for several years after which it will need to be stripped and re-applied, but it will help your outdoor furniture to last a good bit longer.

In Closing

So, yes, pressure treated wood is safe to use for your outdoor furniture, including picnic tables and chairs, benches, and so forth. We recommend using ACQ (alkaline copper quaternary) treated wood as it’s been found to be the safest. What that means is that, when choosing your wood, you should look closely at the label to make sure what chemicals have been used. (If you can’t determine that, ask someone at the lumberyard or big-box home store for help.)

We hope you enjoyed this article and that it answered all of your questions about using pressure treated wood to make outdoor furniture. If you have more, need advice, or would like to leave a nice comment, please do so in the space below. Best of luck in making your outdoor furniture and have a great summer!

6 thoughts on “Is Pressure Treated Wood Safe For Outdoor Furniture?”

    • Hi Sharon, When building a planter I usually use plastic sheeting on the inside. The soil never touches the wood. This protects the wood from rotting and vegetable roots do not absorb chemicals from treated lumber. See the planter I’ve built here: DIY outdoor planter

      Reply
    • I would expand on these recommendations by saying that that the article does appear to provide some information this. The article asserts that the modern PT lumber is treated with preservatives considered to have low toxicity (considered safe for human interaction). However, it appears that PT wood that is rated for ‘ground contact’ apparently has a higher concentration of chemical in it, so maybe one would want to avoid that type of lumber in vegetable gardens. The more toxic chromate type was stopped back in 2003 I believe, so old landscaping lumber in garden is probably not an issue, since probably any existing old landscape wood has significantly broken down by now, in which case you’re probably are in the process of removing the remnants and maybe even replacing a some or a lot of the the topsoil with with new soil. I suppose placing plastic liners is cautionary protection, but I question using the PT lumber to start with if one is so-concerned. We live in a chemical world and if you’re typically anxious about your environment then you’re probably taking a lot of measures in many aspects of your life to mitigate contact with chemicals. If not, then apparently most of these contemporary PT products are considered safe, tho may want inquire about the specific type of PT lumber you may be buying for your garden, or you may elect to use non treated lumber with the idea that you will likely need to replace it a lot sooner.

      Reply
  1. I have wood from an old deck we built in the 80’s. I was planning to use it for walkways in my garden. I’m pretty sure it’s pressure treated. Is it safe to use that way? I have no idea which chemical treatment it had.

    Reply
    • Hi Donna,
      If the walkway is too close to your plants, I would probably not use that wood. When it rains, the chemicals will seep into the soil, and you don’t want more chemicals in your garden.

      Reply
  2. I am impressed your deck is not in serious need for replacement. I would say that most of the toxic preservatives have already seeped out into your garden and maybe even a little bit into your own body if you were in direct contact with it regularly. Note that you have been living all these years with that deck; what can you say about experience healthwise? I would assess (for myself) that if I have not been experiencing issues before and in particular, recently, then the deck wood should be ‘safe’ today, but you have to make you own assessment for your own health.

    Reply

Leave a Comment