How Long Does Pressure Treated Wood Last

How Long Does Pressure Treated Wood Last?


Wooden furniture should be protected from natural factors like rotting and pests. This is very true, especially with wooden patio furniture.Pressure treatment is one of the most trusted ways to preserve the beauty and use of wood. When wood is pressure treated, it will be rot-free and pest-free.Here are some important facts about pressure treated wood so you can find out if this is the material of choice for your project.  

How long can pressure treated wood last?

According to expert woodworkers, pressure treated wood will last a long time. Therefore if you are looking for a good building material for your home or to build furniture then you might want to invest in pressure-treated wood.

The Forest Products Laboratory and other research groups have provided information that treated wood stakes placed in the ground can remain without any signs of rot for more than 40 years! On the other hand, pressure-treated wood made into decks or flooring can last for only 10 years simply because the surface of wood made into decks receive a lot of traffic compared to wooden stakes-placed on the ground. Still, there are reports from the Forest Products Journal that the average pressure-treated deck is only good for 9 years.

What you must remember is that pressure treating makes the wood resistant from rot and pests, however, it will not make wood resistant to water. Pressure-treated wood can still be affected by water when it is soaked or splashed. After pressure treated wood gets soaked, wood can crack, twist, bend and cup until it tears apart. But you can prevent these from happening using simple preventive measures.

You can have lovely pressure-treated decks for a long time when you apply an annual dose of maintenance. You can keep wood stable by applying a coat of water repellent treatment. This should be applied to all the surfaces of the wood before it is used or installed.

You must fasten deck boards using long corrosion-resistant screws. Should there be exposed raw wood as you install hardware, drill, and cut, brush-treat these as you work? Be sure to apply water repellent periodically to keep the boards looking bright and to reduce the uptake of water.

A better way is to use pressure treated wood with water repellent chemicals included. These chemicals were added during the pressure-treating process so you don’t have to periodically maintain your wood. The water repellent is injected deep into the wood together with the preservative. This will help prevent water damage and thus will make your wood last for a longer period of time.

Chemicals used in pressure treated wood

In the process of pressure treating wood,chemicals are used. Usually, the preservative chemicals are driven a short distance into the wood in a special container that combines pressure and vacuum. A few important factors in determining if the pressure treatment process is successful is the amount of chemical preservative that was injected into the wood and the depth of penetration. These characteristics are specified in results-based standards for the amount of time pressure treated wood will last. 

Pressure treated wood used in the construction industry has been treated in the past with the chemical known as chromated copper arsenate (CCA). Because of the reported adverse effects of CCA, US and Canada construction companies began a transition away from the chemical CCA for residential uses in January 2004.

An alternative to CCA is amine copper quat (ACQ) and copper azole(CA). On the other hand, CCA is still being used in the manufacture of shakes and shingles, permanent wood foundations, and in non-residential uses such as the manufacture of utility poles for electrical and cable service.

What makes CCA a good wood preservative anyway?  In CCA, copper is the primary fungicide, arsenic is a secondary fungicide and an insecticide while the chromium is a fixative that offers UV resistance or sun protection to the wood. CCA is applied to wood in a water solution and binds to the wood to create a virtually insoluble precipitate.This means that it is impossible to remove CCA in pressure treated wood.

Ammoniacal copper zinc arsenate (ACZA) is another alternative to CCA with a limited range of applications. Amine copper quat (ACQ) is an alternative to CCA and has been commercially available in the USA,Europe, and Japan. This contains copper as the primary fungicide and a quaternary ammonium compound as the other fungicide.


Pressure treated wood lasts for years with reports that it can last for decades. Pressure treating wood helps prevent rot and pests but won’t stop water from affecting wood. Over the years, CCA or chromated copper arsenate has been used top reserve wood but lately, this was banned from being used in residential applications. A few chemicals are now being used as a replacement but CCA continues to be used in commercial applications and some residential applications as well.

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