What is Treated Wood? Its Advantages and Disadvantages

In a process or treatment, the properties of wood, timber, wood structures, or engineered wood are enhanced by preservative chemicals, such wood is called treated wood. There are many types of these treatments. Each treatment has several processes that are dependent on each other.

Treated wood is more durable than other common wood. This process is known as timber treatment, lumber treatment, or pressure treatment. Because this wood is preserved by chemicals to prevent rot and insects. After this process takes place, the life of the wood increases manifold. Because in this process all the insects and fungi present inside the wood are destroyed. And even later the insects do not reach the wood for a long time.

Pressure treatment is a long process in which a heavy machine is used for large pieces of wood. In this process, the wood is kept at high pressure in a large cylinder with chemicals.

Let us understand this process in this blog in detail.

How Is Pressure Treated Wood Made?

1. Right Thickness of the wood

Before starting this process, we make several bundles of timber. The thickness should not be too much. Due to the high thickness of the wood, the chemicals do not reach inside the wood properly. Therefore it is very important to have the right thickness of the wood.

2. Making pressure in cylinder with chemicals

The bundle of wood is inserted into a long cylinder whose length varies from 80 feet to 220 feet. The diameter of this tube is about 7 – 8 feet.

After inserting wood into the cylinders, all the air inside is removed with the help of a vacuum motor. Chemicals are then filled inside the cylinders. In which the wood is completely immersed.

After that, the pressure inside the cylinders tube is increased so that the chemical penetrates into the wood well.

The pressure inside the cylinder is about 140–150 psi, this is for several hours. This pressure is different for different types of wood. There is some softwood which requires work pressure like 80 – 90 PSI.

3. Open the cylinder and remove the wood

Chemical drops keep falling from the wood.
Chemical drops keep falling from the wood.

The wood is taken out of the cylinder after completing the pressure treatment process. Chemical drops keep falling from the wood. And do not move the wood from its place until the chemical drops stop falling. Even after the drop of chemical drops, there is a lot of moisture in the wood. It takes about 48 hours (4 days) to dry such wood during the summer season. While it takes one to two weeks to dry completely in the winter.

What Chemicals Are Used for Pressure Treated Wood?

One of the famous chemicals uses for pressure-treated wood is Chromated copper arsenate (CCA).  In this treatment, copper is the primary fungicide, is a pesticide, and also provides ultraviolet (UV) light resistance.

This chemical has been used for centuries in the wood preservation process, but on 1 January 2004, the Environmental Protection Agency (EPA) entered into an agreement with the wood industry. In which it was decided that further use of Chromated copper arsenate (CCA) should be completely stopped as it is harmful to the health and environment.

Nowadays Alkaline copper quaternary (ACQ), copper azole (CA), or micronized copper azole (MCA) chemicals are used for wood preservation. After the Chromated copper arsenate (CCA) is completely banned.

Types of Pressure-Treated Wood

There are mainly two types of Pressure Treated Wood.

  1. Above-ground pressure treated wood 

As the name suggests, This type of wood is used at a height of 6-inches from the ground. We use above-ground pressure-treated wood in a place where it can be easily maintained or replaced and also where the wood gets ventilation and drainage. 

Above-ground pressure-treated wood is kept away from moisture as this wood has a short life but is still stronger than normal wood.

  1. Ground-contact pressure-treated wood

Ground-contact pressure-treated wood can be used for both above ground and ground close purpose.

This type of treated wood is mainly used for elevation less than 6-inches of the ground. This type of treated wood has less chance of getting spoiled by moisture. Because this wood treatment has chemical retention and protection of two levels.

As we know that soil contains insects and moisture which damages the wood. So the wood coming in contact with the soil is more likely to spoil. Ground-contact pressure-treated wood is used in such places. Such wood is more durable.

Advantage of Pressure Treated Wood

  1. Insect-resistant: Wood is protected by chemicals. Due to the durability of used elements such as nail, screw, etc. is increased.
  2. Good Durability:  wood preservation contains protective chemicals. This protective treatment prevents any fungal decay from occurring and makes the wood last longer.
  3. Affordability: It is cheaper than any other variety. As compared to redwood or cedar, In large projects, we can save 30 – 40%.
  4. Good Strength: This type of wood is strong, it is also resistant to scratches and dents. This type of wood is perfect for long-term use.
  5. Less Care:  This type of wood requires less care because it is rough and tough. Their repair and maintenance costs are also less. So Homeowners need less care.

The disadvantage of Pressure Treated Wood

  1. Chemicals are used in Pressure Treated to protect the wood. Which is harmful to the environment and health. So it is not good to use this type of wood for kitchens and bedrooms. The chemicals inside this wood make it poisonous. So that we cannot use cutting boards or any food preparation surfaces. If you do not use this type of wood indoor then a better decision will be. 
  2. Warping and Shrinkage:  During the process, wood contains a large number of chemicals, which causes moisture in the wood.
  3. It may take several months for the wood to dry completely. There will be some shrinkage and warping of the lumber as it dries. Therefore, after drying this Wood completely, it will be right to coat the paint and primer.
  4. Chemical Risk: There is a lot of chemical risk in this type of wood, which is not good to use in the garden. Burning this type of wood spreads harmful gases in the environment which are harmful to humans and the environment.

What is Pressure Treated Wood Used For?

Pressure-treated wood can be used for outdoor, wall siding, outside stairs, and home ceilings. As we saw in the line above, pressure-treated wood contains chemicals that protect the wood from insects and termites. But these chemicals are also harmful to humans. Pressure-treated wood powder irritates eyes, skin, and nose.

Guide to Working With Pressure-Treated Lumber

Guide to Working With Pressure-Treated Lumber
Guide to Working With wood preservation
  • While working with Pressure Treated Wood, wear gloves in your hands, and keep hands away from the face while working. Wash your hands well after the work is over.
  • Use eye protection goggles so that the dust of the wood does not harm your eyes. 
  • Always keep wood away from children and animals. Try to cut the wood out of the house. 
  • Use paint only after the Wood has completely dried. Because it dries and shrinks over time, which spoils the paint.
  • Do not burn a piece of wood during construction. Because it is harmful to the environment and to humans. 

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