How To Tell If Wood Is Treated? – Wood Treatment Explained

In the process of pressure treatment, positioning the wood in a de-pressurized water reservoir helps remove the air. Then, people apply a preservative substance over the wood to better protect it against vermin, insects, mites, and fungus. 

However, in some cases, the wood still got treated, and you didn’t even know. Then, how to tell if wood is treated? Browse through our article to learn some valuable tricks. 

6 Ways To Tell If Wood Is Treated


Pressure-treated lumber nowadays comes with stamps and end tags that show the presence of chemicals. Because of the treatment process, pressure-treated wood is either brown or green. In addition, treated wood can feature an oily odor instead of the pleasant natural smell of the untreated type. 

If the lumber involves a pressure treatment, its longevity can last for a few decades, maybe even up to 40 years. If you want to build a shade, a treehouse, or a garage, you have to employ long-lasting wood products. 

Below are some things you should take into account to determine whether or not wood is pressure-treated.

Know About Softwoods

Before finalizing whether a piece of wood is pressure treated or not, you should become acquainted with two types of wood: softwoods and hardwoods. In general, almost all pressure-treated wood falls in the softwood group, with the majority being coniferous plants like spruce, white pine, yellow pine, and Douglas fir.


Because softwoods contain much more sap than hardwoods, they produce naturally wetter lumber. You will notice the presence of excess sap in the softwood, explaining why pressure treatment is essential to extend the lifespan of the softwood. 

Moreover, the natural sap pathways allow pressure-treated chemicals to penetrate deeper into the cells of the wood. 

So, if you see the wood and can conclude it is hardwood, there is a high likelihood that it is not pressure-treated.

Check for an End Tag

Examine the piece of lumber to see if it has a pressure-treated stamp. An end tag labeled on your treated wood would include pertinent information, preservation company, rating, and the name of the preservatives employed for the treatment. 


Avoid any treated wood that comes with Chromated Copper Arsenate (CCA) at all costs. There is an amount of arsenic in this particular preservative. People consider it to increase the risk of cancer. CCA-treated woods are ineligible for use in playgrounds, decks, or any residential structures.

Find The Stamp

CCA-treated wood is still popular with commercial builders and contractors for structural support and industrial projects. If there is pressure treatment on your wood after the ban of CCA in 2003, the most likely chemical used is alkaline copper quaternary (ACQ).

When looking closely, you will notice a stamp “L P22” somewhere on that wood, indicating that the treated wood contains arsenic. And you don’t have to worry because arsenic is one safe variety. Treated wood can endure direct contacts from the ground, such as fence posts or structural support. Although wood with the stamp “L P2” is not toxic, you should not employ it to build playsets or even home furniture.

The foundation comes with an “FDN” stamp, which is the safest type of pressure-treated. As regards incorporating it as the base underneath the floors of your house, it is ubiquitous among thousands of builders. 

Additionally, pressure-treated wood containing borates as the chemical is safe for in-house uses and poses no risk to humans. Find the stamps with the abbreviations, such as “Tim Bor,” “Hi Bor,” or “Bor,” to identify borate-treated lumber.

Check The Color of the Wood

If the wood you are scanning doesn’t have an end tag, you might be wondering how to determine if it’s been treated. This, however, should not concern you. 


One of the simplest ways to tell if the wood has no stamp is to look at the colors carefully. If the wood exhibits a faint olive-green color, you can tell that it is pressure-treated wood. If your wood is too old and worn down to see any color other than gray, you can cut a piece of it at an angle to see the color.

Thousands of DIY builders and woodworkers prefer to use borate-treated wood for their in-house furniture because it is strongly resistant to termites. Even though people consider this wood safe with a low level of toxins, it is still not suitable for open uses, particularly in outdoor locations.

Carry Out A Smell Test

If you can’t scan out any end tags or stamps, and you’re having trouble identifying any green or blue tint on the surface of your wood, you can sniff a chunk of wood deeply. If the wood is treated, you can not make out a pleasant, fresh, natural scent. The majority of pressure-treated woods have a chemical or oil odor. 

CCA-treated wood is the most dangerous, even when it has a pleasant smell. The reason is this type of wood has no discernible odor. If you suspect or intend to use wood older than 2003, you can cut a piece to check whether it is pressure-treated wood.

Chemicals Used for Pressure Treatment of Wood

Treated wood before the year 2003 contains one type of chemical known as Chromated Copper Arsenic. Today, people consider this chemical now hazardous, despite being the most effective substance for treating lumber. It has UV resistance, which protects the wood from discoloration and other problems. 

Another excellent wood preservative is Copper azole. It is low in toxins and does not affect the soil even if it contains elements that seep into the soil.

Copper Naphthenate is also a popular chemical used to treat woods such as railroads, greenhouses, fences, etc. It is ideal for woods that come into contact with the ground or water. 

Borate is one of the safest substances used in pressure-treated wood because it is non-toxic to humans and the environment. Its constituents inhibit the growth of fungi and molds. 

Further watching: How To Do A Borate Wood Treatment?

Because it consists of a high amount of coal, creosote preservative is another preferred chemical for many types of wood, primarily used for industrial purposes, such as railroads.

Final Words

Hopefully, our article has helped provide you with helpful information on how to tell if wood is treated. Identifying the pressure-treated wood is no longer a matter. You can contact us if you have any other questions. Please, feel free to ask!