Do Fence Boards Need to Be Pressure Treated?


So you are looking for a new fence for your backyard. You may have come across the idea of a “pressure treated” fence. What does that mean? Is it necessary?

Fence boards need to be pressure treated. When fences are not pressure treated, they are exposed to the elements and the fence will deteriorate faster than a pressure treated fence will. Pressure-treating fence boards prevent the growth of bacteria and fungi. 

Now that you know that your fence needs to be pressure treated, what is next?

Why Fence Boards Need to Be Pressure Treated

Fence boards need to be pressure treated to protect the wood from being ruined by outside forces.

If you think about it, fence posts are in the ground, where the soil is typically moist. Moisture creates a dangerous place where wood can rot easily and quickly.

Fence posts are also exposed to insects when in the ground, which can also damage the wood.

So, the boards you use need to be pressure treated to protect the wood and extend the life of the wood and ultimately your fence.

Without pressure treatment, some woods can only last a year or two when touching the moist ground.

How is Wood Pressure Treated?

Pressure-treating wood is a process, but it protects your wood so it will last eight times longer than untreated wood. So, what is this mysterious process of pressure treating wood? Keep reading to learn the process step-by-step.

Step One: Place the wood in the pressure chamber

When a fence board is pressure treated, the wood is placed in a pressure chamber, where all of the air is forced out of the chamber and the wood.

Removing the air from the wood is important because it makes room for the preservative solution.

Step Two: Add the preservative solution

When all of the air is removed, the pressure chamber is then filled with the preservative solution.

The solution is a mix of different chemicals that will protect the wood.

Step Three: Pressure treat the wood

Next, pressure is applied in the chamber where it forces the preservative solution into the wood.

The solution goes deep into the wood cells where the air used to be to completely coat the wood.

Step Four: Drain the pressure chamber

After the wood has been properly treated, the pressure chamber is drained. Once all of the liquid is removed, a vacuum pump removes the rest of the excess solution that is on the wood.

Step Five: Let the wood dry

The wood is removed from the pressure chamber and placed on a drip pad to dry. The drying process could last from 24-48 hours, depending on the weather.

Now that the wood is dry, it is ready to be sold!

The video below is a great resource to learn about how pressure treated wood is made.

How quickly does a non-pressure treated board rot?

When non-pressure treated wood is placed outside, it can last anywhere from 2-5 years.

It does depend on a few things such as the weather, exposure to sunlight, and how well you maintain the structure, but it does not last as long.

Do fence boards come pressure treated?

Fence boards do come pressure treated so you don’t have to think too much about this whole process. It’s done for you.

When you are shopping for lumber at your local home improvement store, you will have the option to buy pressure treated fence boards. Just give it a look to be absolutely sure you’re getting the right stuff.

How to Tell the Difference Between Treated and Untreated Wood

The biggest difference between pressure treated and untreated wood is the color. Pressure treated wood will have a green tint to the wood.

Pressure treated wood will also have a different smell to it. It will smell like chemicals since that is what they use in the pressure-treatment process.

There should also be a tag informing you that the wood is pressure treated.

Types of Pressure Treated Wood

When looking for pressure-treated wood, it is important to think about what you will use the wood for. There are two types of pressure treated wood: above ground and ground contact.

Depending on what type of fence you are building will depend on the type of pressure-treated wood you will need to buy and use for your fence boards.

Above-Ground Pressure Treated Wood

If you are wanting to build a fence, this may not be the option for you.

Above-ground pressure-treated wood needs to be at least six inches above the ground to work properly. There also needs to be proper ventilation and drainage.

This type of wood may not work as effectively for a fence.

Ground-Contact Pressure Treated Wood

Ground-contact pressure-treated wood can be used above ground and in contact with the ground.

It is safer to use in contact with the ground because it is treated with twice the amount of chemicals compared to above-ground pressure-treated wood.

When looking for pressure-treated wood for your fence, make sure to note which type of wood it is and if it will work for what you are building.

It’s Worth the Cost

Price is always something to note when looking into starting a project. Building a fence is no different.

The chart below shows the cost compared between pressure treated and untreated wood. The price is for a typical 1x6x6 piece of wood because that is the standard size of a fence board. These costs come from The Home Depot.

Pressure TreatedUn-treated
Cost$6.16/board
$36.98/pack of 6
$2.67/board

Pressure treated boards are going to cost more because of the extra process and the chemicals added to the boards.

But, when you think of how much longer these boards will last over the untreated boards, you will realize how much money you will be saving.

For example: Say you used untreated wood in your backyard for your fence. The typical replacement time is every 2-5 years. For this example, say you replace your fence after 5 years.

Take $2.67 (the cost for one board of untreated wood) x 8 (the number of times you would replace your fence in 40 years) =$21.36

And that is only for one board!

At the end of the day, pressure treated wood will protect your fence longer and will save you more money.

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