Post Updated: June 27, 2026
If your Northern Virginia deck, fence, or playset was built more than about twenty years ago, there is a good chance the wood was treated with chemicals we no longer use around homes. It is worth understanding what you have, whether it is a concern, and what to do about it, because the rules on pressure-treated wood changed in a big way in 2004.
Is old pressure-treated wood dangerous?
Short answer: older pressure-treated lumber, the kind used on most decks and fences built before 2004, was treated with chromated copper arsenate (CCA), which contains arsenic, a known carcinogen. The EPA does not require you to tear out existing CCA structures, but it is smart to handle the wood carefully, keep it sealed, and keep vegetable gardens and bare hands off of it. Pressure-treated wood made since 2004 uses safer copper-based preservatives instead.
What was in old pressure-treated lumber?
For decades, the standard pressure-treated wood at every lumberyard was treated with CCA, a blend of three chemicals: chromium, which binds the preservative to the wood; copper, which fights fungus and decay; and arsenic, which kills wood-boring insects. It gave the lumber its familiar greenish tint and made it remarkably rot- and termite-resistant. The problem is the arsenic, which is a known human carcinogen and can leach from the wood over time.
When did pressure-treated wood change?
In 2002, the wood-treatment industry and the EPA agreed to voluntarily phase CCA out of residential products. That change took effect at the end of 2003, so from January 1, 2004 onward, new CCA-treated wood was no longer sold for residential decks, fences, playsets, and similar uses (it is still used for some industrial applications like utility poles). The practical takeaway for homeowners is simple:
- A deck, fence, or playset built before about 2004 may well be CCA-treated wood containing arsenic.
- Anything built after 2004 is almost certainly one of the newer copper-based treatments, with no arsenic.
(You may have heard that arsenic-treated wood was “banned in Europe decades ago.” That is not really accurate. The major shift away from arsenic in residential lumber happened in the early 2000s, and Europe restricted it around the same period, not fifty years earlier.)
How do I know if my deck has old CCA wood?
The most reliable clue is age: if it went up before 2004, treat it as CCA until you know otherwise. Both old and new treated wood can look greenish when fresh and weather to gray, so color alone will not tell you. If you want certainty, inexpensive arsenic test kits are available, or a contractor can help you assess it. When in doubt, assume it is CCA and take the sensible precautions below.
What are the risks, and what should you do?
Here is the reassuring part: the EPA does not recommend ripping out existing CCA structures. It does recommend reducing your exposure, which is easy to do:
- Keep it sealed. Applying an oil-based penetrating stain or sealer every year or two significantly reduces how much arsenic can leach from the surface.
- Mind your garden. Do not grow vegetables or herbs right up against old CCA wood, since toxins can move into the soil. Wash hands after contact, especially children’s.
- Never burn it. This is the big one. Burning pressure-treated wood, old CCA or modern copper-based, releases toxic smoke and ash. Old CCA wood releases arsenic when burned. Never put it in a fireplace, campfire, fire pit, or barbecue.
- Work carefully. When cutting or removing treated wood, wear a dust mask and gloves, work outdoors, avoid breathing the sawdust, and clean up thoroughly.
- Dispose of it properly according to your local rules, not by burning.
Is modern pressure-treated wood safe?
Yes, much safer. Since 2004, residential pressure-treated lumber has been made with copper-based preservatives instead of arsenic, most commonly alkaline copper quaternary (ACQ) and copper azole (CA), and newer “micronized” versions of those. Copper does the heavy lifting of resisting rot and insects, and it poses far lower risk to people and pets. You still should not burn it, and wood decks still benefit from regular sealing, but the arsenic concern is gone.
The hardware problem: why old fasteners fail on new wood
Here is a catch that trips up a lot of do-it-yourself repairs. The newer copper-based treatments are actually more corrosive to metal than the old CCA was. If you attach modern treated lumber with the wrong fasteners, or bolt new boards onto an old structure with old hardware, the metal can corrode quickly and weaken the connection, which is a real safety issue on a deck.
For any project with modern pressure-treated wood, use hardware rated for it:
- Hot-dipped galvanized (look for a G-185 coating) or stainless steel nails, screws, bolts, joist hangers, and connectors.
- Never put bare aluminum in contact with copper-treated wood, it corrodes fast.
- Do not reuse old or lightly plated fasteners on new treated lumber.
Matching the right hardware to the wood is exactly the kind of detail that separates a deck that lasts from one that quietly fails at the connections.
Should you replace an old pressure-treated deck?
Not automatically. If your older deck is structurally sound, you can keep it in service by sealing it regularly and following the precautions above. Consider replacing it if it is showing rot, loose or corroded connections, or other signs of age, or simply if you would rather not have arsenic-treated wood around kids and pets. When we rebuild, we use modern materials and the correct corrosion-rated hardware throughout.
We inspect, repair, and build decks in PVC, composite, and modern pressure-treated wood. If you are not sure what you have or whether it is still safe, see our decks and porches or browse some recent projects. For more on keeping any deck healthy, our guide to deck care covers cleaning, sealing, and the yearly structural check.
Old pressure-treated wood FAQs
Is old pressure-treated wood dangerous?
Older pressure-treated wood built before 2004 was usually treated with CCA, which contains arsenic, a known carcinogen. The EPA does not require removal of existing structures, but you should seal the wood, keep gardens and bare hands away from it, and never burn it.
How do I know if my wood contains arsenic (CCA)?
Age is the best indicator: wood installed before 2004 is likely CCA. Color is not reliable, since old and new treated wood can both look greenish. Arsenic test kits are available if you want to be sure.
Can I burn pressure-treated wood?
No. Burning any pressure-treated wood, old or new, releases toxic smoke and ash, and old CCA wood releases arsenic. Never burn it in a fireplace, fire pit, campfire, or barbecue. Dispose of it according to local rules instead.
Is new pressure-treated wood safe?
Yes, it is much safer. Since 2004, residential treated lumber uses copper-based preservatives such as ACQ and copper azole, with no arsenic or chromium. It still should not be burned, but it poses far lower risk to people and pets.
Why does treated wood need special fasteners?
Modern copper-based treated wood is more corrosive to metal than old CCA. Use hot-dipped galvanized (G-185) or stainless steel fasteners and connectors, and never put bare aluminum against treated wood, or the hardware can corrode and weaken the structure.
Should I replace my old pressure-treated deck?
Not necessarily. A structurally sound older deck can be kept in service by sealing and maintaining it. Replace it if it shows rot or failing connections, or if you would prefer not to have arsenic-treated wood around your family.
About the author: Michael Kayne is the owner of Main Street Home Improvement, a licensed and insured Class B contractor that has built, repaired, and replaced decks for Northern Virginia homeowners since 2010 from its home base in Vienna, VA.
Wondering whether your older deck is still safe, or ready to replace it? Request a free consultation or call 703-587-7762, and we will take a look.