Different Treated Lumber and Its Uses

Different Treated Lumber and Its Uses

April 1, 2023

Heavy gauge wood boards

With spring right around the corner, you may have a multitude of projects starting to pop up that are taking place outdoors such as landscape work, fencing and decking installations, roofing projects, and more! You may know what lumber is used for certain projects, but do you know why? Do you know how this lumber is made, or what it is made of? Don’t worry, we have you covered! Keep reading to find the answers to all of your questions. First things first. What is treated lumber?

There are two main types of treatment that are seen in our industry – pressure treated and fire treated. The actual treatment process for both is the same – the lumber is put into a large cylindrical container that is filled with chemicals. It is then pressurized to penetrate the wood. Therefore, technically fire-treated is a type of pressure treatment. However, in our industry “pressure-treated” wood typically refers to the greenish-colored lumber that is resistant to decay, termites, mold, etc. It is the material that is used in permanent outdoor and weather-exposed applications. On the other hand, fire treated is specified in commercial applications and installation areas where there may be a higher concern for fire safety.


Pressure Treated – Green Lumber & Marine Grade


What Is It?

Pressure-treated lumber is a soft wood (usually Southern Yellow Pine or Douglas Fir) that goes through a pressure-impregnated treatment process that enables the lumber to withstand the elements.

What Is It Used For?

Pressure-treated wood protects exterior applications from decay, rotting, termites, mildew etc. The wood can be used in above-ground applications such as a deck or fully submerged in salt water. Above ground has the lowest chemical retention and saltwater submersion has the highest retention treatment. In general, there are 4 types of applications – Above Ground, Ground Contact, Salt Water Splash, and Salt Water Submersion. Each application has a different level of treatment to match the specific use of the product. Some of our customers may be a little more familiar with use categories such as UC3A or UC4B. These use categories roughly correspond to the 4 uses given above.  

The most common examples of uses for pressure-treated lumber are for fencing, decking, retaining walls, or any pole/beam that will be exposed to moisture or soil for long periods of time. Some common examples of using marine-grade lumber (saltwater splash and saltwater submersion) include the construction of piers, boardwalks, docks, etc.

Why Is It Used In Outdoor Projects?

Pressure-treated lumber is used in outdoor projects because of its ability to resist rot, decay, and mold, as well as its ability to deter termites and other insects from eating away at the wood. These specific abilities are why it is crucial to use pressure-treated lumber if your project will be exposed to the elements. Using pressure-treated wood is critical to the structural integrity of an outdoor project.

What Is It Made Of?

For a long time, the primary treatment that was used was Chromated Copper Arsenate or CCA. Over the years, the standard treatment has changed and regulations have limited the use of CCA. While CCA treatment is still used in non-residential applications, arsenic-based chemicals have been banned for residential use. The new chemical that is primarily used now is called Micronized Copper Azole (MCA), often branded as MicroPro MCA Treated Lumber. Countless other chemicals exist, but these are the two most commonly used in our market. 


Fire Treated Lumber

What Is It?


Fire Treated (aka fire retardant or fire-rated) wood is lumber that has gone through a specific process that gives it the ability to slow down combustibility. In most cases, a pressure-impregnated fire treatment process is used and required, but there are some paint-on solutions as well. The most common brand name is Hoover, which is what we offer. There are two basic types of treatment – Interior Pyroguard and Exterior Fire-X.

  • Interior Pyroguard is used for applications where the lumber is ultimately covered and NOT exposed to the elements.
  • Exterior Fire-X is for applications where the wood will be exposed to the elements or in a moist environment. The benefit of Exterior Fire-X is that the chemical will not leach out over time. It should be noted that Fire-X is not fully resistant to rotting, decay, etc. like normal pressure-treated wood.


What Is It Used For?

Fire-treated lumber can be used in multiple ways, the following being the most common applications of the product:

  • Exterior architectural trim
  • Building framing and support structures
  • Corridors and hallways
  • Fire barriers
  • Exterior walls
  • Roof construction
  • Interior partitions

So Much To Learn!

There is a lot more to lumber and its different applications than most of us may think. Specific treatments for specific projects are just the tip of the iceberg! As always, here at Frisco Woodline, we aim to keep our customers informed and teach new things to those who are looking to learn. If you have any questions for us then please don’t hesitate to reach out! To see what other products we supply make sure to click the link below. If you are looking to learn more about lumber products or the lumber market, check out the other blogs that we have posted!