Pressure-treated wood is not 100% waterproof. However, it is water-resistant enough to withstand the elements and last for years without rotting or decaying.

There are several different types of pressure-treated wood, each with its own level of water resistance. The most common type is treated with a chemical called chromated copper arsenate (CCA). This chemical helps to repel water and prevent rot.

Waterproof Pressure Treated Wood

Other types of pressure-treated wood include:

  • Alkaline copper quaternary (ACQ)
  • Copper azole (CA)
  • Micronized copper quaternary (MCQ)

Each type of pressure-treated wood has a different level of water resistance.

CCA-treated wood, for example, can last up to 40 years without rotting.

ACQ-treated wood has a slightly lower level of water resistance and may only last for 20-25 years.

The type of pressure-treated wood you use will depend on your needs and budget. If you need a waterproof deck or fence, for example, you may want to use ACQ-treated wood.

If you’re looking for a more budget-friendly option, CCA-treated wood may be a better choice.

Related: How Does Pressure-Treated Wood And Lumber Work?

Does Pressure-Treated Wood Need To Be Sealed?

Although pressure-treated wood kills germs and insects, it does not keep moisture from seeping into the timber. Water can seep into the boards on a deck that will be exposed to rain and cause them to expand and warp.

To prevent this, you’ll need to seal your pressure-treated deck or fence. This will create a barrier that will keep water out and help your deck last even longer.

Sealants are available in a variety of colors, so you can also use them to give your deck or fence a new look.

When Should You Seal Pressure-Treated Wood?

You should wait at least six weeks after the pressure-treated wood has been installed before you seal it. This will give the boards time to dry out and allow the preservative to seep into the timber.

Sealing your pressure-treated wood too soon can prevent the preservative from doing its job.

The Best Waterproofing For Pressure-Treated Wood

There are several different options for waterproofing your pressure-treated deck or fence. You can use a sealant, a stain, or a waterproofing agent.

Sealants are available in clear and tinted options. Clear sealants will not change the color of your pressure-treated wood, but they will add a layer of protection against the elements.

Tinted sealants will add a tint to your pressure-treated wood. This can be a good option if you want to change the color of your deck or fence without having to paint it.

Stains are available in a variety of colors and can help to protect your pressure-treated wood from the elements. Waterproofing agents are clear and help to repel water.

Which option you choose will depend on your personal preferences and the look you want to achieve.

How Soon Can You Seal Pressure-treated Wood?

As soon as the surface of the pressure-treated wood is dry, you can apply a sealant, stain, or waterproofing agent.

You should wait at least six weeks for the pressure-treated wood to cure before you apply any type of sealant, however. This will give the preservative time to seep into the timber and protect it from rot.

FAQs

Can you use flex seal on pressure-treated wood?

Yes, you can use flex seal on pressure-treated wood. This will create a barrier that will keep water out and help your deck last even longer.

Can you use Thompson Water Seal on pressure-treated wood?

Yes, you can use Thompson Water Seal on pressure-treated wood. This will help to repel water and prevent rot.

Do I need to seal pressure-treated wood?

Yes, you should seal pressure-treated wood to prevent water damage. This will help to extend the life of your deck or fence.

Can you use waterproofing on pressure-treated wood?

Yes, you can use waterproofing on pressure-treated wood. This will help to repel water and keep your deck or fence looking new.

What is the best sealant for pressure-treated wood?

There are several different types of sealants available for pressure-treated wood. The best option for you will depend on your personal preferences and the look you want to achieve.

Can you pressure-treat Douglas fir?

Yes, you can pressure-treat Douglas fir. This will help to protect the wood from rot, insect damage, and fungal decay.

Is cedar wood better than pressure-treated?

Pressure-treated wood is the more durable and weatherproof of the two when it comes to comparing treated wood vs. cedar. It’s insect-resistant and rot-resistant, and versions designed for “ground contact” may be buried in dirt and will resist decay for decades.

Do you need a wood preserver on pressure-treated wood?

Yes, you should use a wood preserver on pressure-treated wood to help protect it from rot and decay. Although pressure-treated wood is not waterproof, it will still require protection from the elements.

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