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How Long Does Pressure Treated Wood Last?

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Are you wondering how long pressure treated wood lasts? It is a long-lasting and affordable alternative to many other materials out there. It can last a significant amount of time if cared for properly.

Pressure-treated wood can last up to 40 years with proper upkeep and treatment. Depending on how and where it’s used, what type of conditions it’s exposed to, and how well it is maintained, the life expectancy of pressure-treated lumber can decrease to about 10 years. 

pressure treated garden gate

When working with treated wood, you might wonder how to prolong the durability of your fences or decks and have questions like: will the wood rot, what are the risks of using treated wood, and is this material worth it? Continue reading to learn all of that and more. 

How Does Pressure Treated Wood Differ from Regular Wood?

You can tell from its name that pressure-treated wood undergoes some kind of treatment that changes it from regular old lumber. Pressure-treated wood has gone through a sealing process to make it last longer. When building a fence, pressure treated wood rails and posts are the best options.

How Is the Wood Pressure Treated? 

This process for turning raw lumber into pressure-treated wood involves pressure and a chemical solution that is deeply incorporated into the wood.  

The wood is placed in a depressurized holding tank, where the air from the wood is extracted and replaced with a chromium, copper, and arsenic chemical solution. 

This process makes it a little more expensive than natural untreated wood but well worth the investment for those who choose to use it for the longevity of their construction projects. Because the wood is treated with chemicals, you cannot burn pressure treated wood.

Can I Treat My Own Lumber to Last Longer? 

Due to this complicated process and machinery, it’s next to impossible for homeowners to treat wood themselves, as most of these chemical and pressurized processes come with their risks. 

But an old-known way many have used to treat wood in order to help it last longer is the use of a borate treatment. It simply involves submerging the wood in this solution, and it can help prevent different kinds of insect infestations, like termites. It is also known to prevent decay from fungi. 

With this process, it is usually recommended for homeowners to submerge the wood twice in the solution and allow for it to completely dry before painting or staining.

Why Does Pressure Treated Wood Last Longer? 

The main difference between pressure-treated wood and untreated wood is the durability. The air vacuum and chemical solution do not make treated wood stronger, so how does it work? 

Once treated, the wood has different properties and features that prolong its life:

  • Preservative resists rot and insects. The chemical injected into the wood is a preservative that is chemically-designed to resist rot – and that is what helps keep insects away. Without wet, rotted wood, there is nothing for bugs to eat or live in. 
  • Pores are sealed by chemicals. So boring insects can’t get in. 
  • The coating repels moisture. After construction, a water-repellent sealer is applied to all exposed surfaces. 

Natural lumber doesn’t have these protections, though some woods are more naturally resistant to bugs and rot than others, such as redwood, cedar, teak and tropical hardwoods (ipe, cumaru, etc).

However, all of these woods are costly. Pressure-treated lumber is usually a less expensive wood like yellow pine, making it quite a bit less than those pricier alternatives. 

In general, an untreated wood fence will be more quickly affected by water and fungi, making its durability not as reliable as a treated fence. 

Talking about fungi, this brings the next question.

Does Treated Wood Ever Rot?

Yes, pressured-treated wood will eventually start to decay. As mentioned above, it can take years due to the preservatives added, but it does not mean it will last forever. Most treated fences start to decay after 15 years, as reported by a variety of homeowners.

  • Water and fungi cause decay. The usual cause of decay is fungi exposure that eventually starts to eat up the wood. Other causes can be termites or constant water exposure. So, it is highly recommended to keep your treated wood dry at all times.
  • Proper care prolongs wood’s life. Even if the wood has been treated to increase its resistance, it is crucial to understand how to properly care for it so its durability can be prolonged as much as possible. 

Learning to maintain and treat your pressure-treated wood will add years to the life of your projects. 

How to Properly Care for Your Treated Wood Fence or Deck

Your treated Wood Fence or Deck, if not properly maintained, can be susceptible to many naturally occurring problems such as Sprinkling and swelling, Mildew Growth, and Ultraviolet damage. Different actions must be taken to prevent each type of damage. 

A Sealer Reduces Shrinking and Swelling

Shrinking and swelling are direct results of either water absorption or water loss in your pressure-treated wood. This can alter the appearance of the wood, such as warping and twisting defects. 

The best practice to avoid this problem is to apply a sealer or a stain that is specially made for pressure-treated wood. 

Clean and Use Mildewcide to Prevent Mildew growth 

Mildew growth is a common issue when the wood is exposed to humid weather conditions. To prevent this from occurring, the wood must be maintained by cleaning the wood with a product that contains a mildewcide. This will ensure that your fence and deck remain clean, fresh-looking, and mildew free. 

Use an Ultraviolet Stabilizer to Minimize Sun Damage

Like anything under the sun, Ultraviolet damage can alter the appearance of your wood by changing the original color. 

The best option to help minimize this damage and slow the ultra-violent decay is to regularly wash your deck or fence and to apply the correct finish. In order to be effective, the Finish must contain an ultraviolet stabilizer. Think of the ultraviolet stabilizer as a sunscreen for your pressure-treated wood.  

Best Practices to Prolong the Life of Pressure-Treated Lumber

Develop a maintenance routine that includes best practices to make your pressure-treated lumber projects have a longer-lasting life:

  • Wash the wood with a cleaner.
  • Let the wood dry.
  • Seal with a water repellent to ensure that the wood is protected. 

Testing to See If Your Sealer is Working

After the repellent is applied, test the wood by putting a slight amount of water to best how well the water is repelled.  

If the water is absorbed into the wood quickly, your sealer isn’t working. You may need a second coat.  Wait at least 24 hours, reapply, then test again for effectiveness. Usually, one coat does the job. 

Can I Burn Old Pressure Treated Lumber in My Fire Pit?

If your pressure-treated fence is ready to be replaced, you may wonder if you can burn that old wood and, if not, what should you do with it?

Due to the variety of chemicals added to treated wood, it is NOT safe to burn

No matter how old the wood is, these toxic chemicals should not be inhaled by humans or put out into the environment. 

The most concerning of these chemicals is arsenic, which can highly disrupt normal cell functioning when high exposure occurs. Because of this, you can’t even put pressure-treated lumber in your regular trash. To dispose of it, you need to call your trash hauler to see what the regulations are in your area. 

Long-Lasting Alternatives to Pressure-Treated Wood Alternatives

In you don’t like the chemical laden pressure-treated wood, common alternatives are, as mentioned above, naturally resistant wood, which can be a little more expensive but does come with fewer risks.

Another option that is growing in popularity is composite decking and fencing. This wood alternative made of wood fibers and plastic makes a very strong, resilient, and long-lasting material for outdoor projects. It can be a bit costly on the front-end, but it can last over 20 years or more with proper care. And “proper care” for composite requires a lot less work than pressure-treated lumber.


Overall, due to its high durability, support and price, pressure treated-wood remains a go-to for many homeowners. It is ultimately a great way to achieve outdoor projects that will last throughout the years. Be sure to checkout our list of the best primer you can use for pressure treated wood!

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Jena Slocum Co-Founder

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