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Does Pressure Treated Wood Need to Be Sealed? (Explained)

Usually, a sealer is used on the outer surface of the wood to prevent moisture, make it water-proof, and prevent fungal growth and rot.

But the pressure-treated wood is already treated with many chemical preservatives that prevent rotting and further damage. Thus, you may wonder if pressure-treated wood further needs to be sealed like regular wood or not.

Therefore, let us go through the answers given ahead to know the facts.

Does Pressure-Treated Wood Need To Be Sealed?

Pressure-treated wood needs to be sealed to prevent the continuous circle of swelling and contracting over time which can cause the pressure-treated wood to become warped, cracked, and rotten. Sealer on pressure-treated wood also will increase its average usable life and make it look better.

Pressure-treated must be sealed with a sealer even though it is treated in a pressured chamber where it was infused with several chemicals to prevent damage and rotting.

The main purpose of sealing pressure-treated wood is to protect the wood from being rotten, cracked, warped, and splintered. 

Many pressure-treated wood grades are claimed to be somewhat water-proof but it’s actually not, water can still seep through the wood, especially if the wood is exposed to a water body.

And over time moisture will make it swell and sunlight will make it shrink, thereby, this continuous circle of swelling and shrinking will cause cracks and warps in the wood, and excess moisture will cause rot in no time. 

But if a suitable sealer is used on the surface of pressure-treated wood once a year, it will make the wood water-proof to quite a good extent which will help prevent crack, rot, and warp in the wood.

Moreover, sealing the pressure-wood surface will protect the wood from UV rays which will prevent the early fade away of color, and sun bleaching. 

Also, below whether you need to seal an already cut pressure-treated wood and fence made of the pressure-treated wood have been explained to make these queries clear. 

Cutting Pressure-Treated Wood:

When pressure-treated wood is treated with chemicals, only a little amount of chemicals reach the center of the wood.

So, when pressure-treated wood is freshly cut, it becomes more susceptible to moisture accumulation and over time can rot, get mold, and get cracked up.

As a result, freshly cut pieces of pressure-treated wood need to be sealed with a pressure-treated wood sealer as immediately as possible to prevent early decay and mold.

Pressure-Treated Wood Fence:

To prevent potential rotting, mold, cracks, and insect infestation, it’s a must to seal a pressure-treated wood fence. A pressure-treated wood fence that is installed outside is exposed to rainwater, snow, and dew.

Over time, moisture/water will penetrate the wood and make it go through a circle of swelling and shrinking which ultimately will cause cracks, mold, and rot in the fence. But applying sealer will help prevent these potential threats and will ensure a longer lifespan.

Is It Better To Stain Or Seal Pressure-Treated Wood

It is more advisable to stain pressure-treated wood rather than sealing it.

Wood stains are paints for the exterior surface of pressure-treated wood that is found in transparent, semi-transparent, semi-opaque, and solid colors.

It works similarly to a pressure-treated wood sealer because a wood stain protects pressure-treated wood from moisture, rot, crack, mold, and mildew. Moreover, staining pressure-treated wood will protect the wood from UV rays as well as sun damage that can cause early graying. 

But sealing pressure-treated wood will only provide protection from moisture penetrating the wood and causing rot, mold, and mildew in the wood.

Since a pressure-treated wood sealer is a slightly colored oil or water-based thing, it will not protect the pressure-treated wood planks from UV rays and sun damage, thus, wood can become gray sooner. 

Therefore, comparing the advantages of both a wood sealer and wood stain on pressure-treated wood, you should stain pressure-treated wood.

What Happens If You Don’t Seal Pressure-Treated Wood?

If you do not seal pressure-treated wood, the pressure-treated wood planks can go through any of the consequences described and listed below.


Pressure-treated wood is not water-proof at all, thus, moisture can penetrate the wood if it’s not sealed, especially if the pressure-treated wood is exposed to any water body, rain, snow, and dew.

Over time, moisture/water seep into the planks of pressure-treated wood and they swell, and again under sunlight the wood planks dry and shrink.

And when this circle of swelling and shrinking of pressure-treated wood will keep going on, the wood planks will end up getting cracked up. 


As mentioned just above that if pressure-treated wood is not sealed, water can seep into it. If it is continuous to have happened, water/moisture sometimes isn’t fully dried up and then the wood becomes very susceptible to fungis.

Fungi will be feasting and surviving on the retained moisture in the wood causing the pressure-treated wood rot.

Water Damage:

Excess water in the pressure-treated wood can make the wood decay too without letting any microorganisms to feast on the moisture in pressure-treated wood.

Color Fades Away:

Nowadays, many pressure-wood sealers come with additives that somewhat can help protect the pressure-treated wood from harmful UV rays.

But when the pressure-treated wood is not sealed, it’s not protected from the UV rays that can cause an early fading away of the natural wood color and can make them appear gray.

Usable Lifespan Lessens:

When the pressure-treated wood is sealed regularly, moisture can’t penetrate, therefore, the planks of pressure-treated wood remain free from cracks, warps, molds, and mildews. It saves the repair cost every time and increases usable lifespan.

But when pressure-treated wood isn’t sealed regularly or at least once, all or any of the above-mentioned damage will be caused that eventually will lessen the lifespan of the pressure-treated wood.

How Long Do You Have To Wait To Seal Pressure-Treated Wood?

You need to wait for at least a month/30 days to seal pressure-treated wood. 

Anything made using the pressure-treated wood must need to be dried out fully before applying a sealer onto the pressure-treated wood’s surface.

It’s because pressure-treated wood is treated using several chemicals, so after building up anything those chemicals in pressure-treated wood require about a month of dwell time so that it can get ready to soak up a sealant.

If pressure-treated wood isn’t dried fully before sealing, it may leave moisture behind, thereby, sealant won’t be absorbed properly.

How To Seal Pressure-Treated Wood?

To help you seal pressure-treated wood, here step-by-step instructions are added. You can follow this guide before you seal pressure-treated wood.

Let Pressure-Treated Wood Dry:

After installing or building something with pressure-treated wood, wait for one month at least so that the wood can get enough time to dry completely and be ready to soak a sealant. 

Choose The Right Sealant:

Sealants are available as both water-based and oil-based sealants, you can choose either of them or whichever suits the pressure-treated wood product the best. 

Prepare The Pressure-Treated Wood: 

Now before you apply sealant, the pressure-treated wood needs to be cleaned thoroughly, thus, use any commercial wood clean the build-up dirt. dust, and debris. Then pressure wash the wood and let it dry completely.

Apply The Chosen Sealant:

Only after making sure the pressure-treated wood is dry, start applying your chosen sealant. Start with applying in a small area to see if the sealant is adhering to the wood or not.

Once, you got the desired result, use a paint pad applicator and apply a sealant to the rest of the surface. A paint pad applicator is usually better than a brush for applying sealant because the sealant is applied faster, smoothly, and evenly with a paint pad applicator. 

 Usually, just one coat of the sealant is enough but if you think another coat of sealant is needed on the pressure-treated wood, you can opt for but only after the first coat is dried fully. 

Allow The Sealant To Dry:

In last, let the sealant on the pressure-treated wood surface dry fully for at least 24-48 hours. And make sure water can’t drop on the sealant. 

What Should I Use To Seal Pressure-Treated Wood?

If you are thinking what would be the best sealant for sealing pressure-treated wood, have a look at the list added below that contains the name of some of the best pressure-treated wood sealants.

  • Ready Seal 520 Exterior Stain and Sealer for Wood 
  • Thompsons Waterseal Solid Waterproofing Stain
  • SEAL-ONCE Nano+Poly Ready Mix Penetrating Wood Sealer
  • Olympic Stain Smartguard Concentrated Multi-Surface Sealant
  • Ready Seal 515 5-Galon Sealer

Final Thoughts

Pressure-treated wood must be sealed because a sealant will protect the pressure-treated woof from rotting, growing mold and mildews, and cracking. Besides, new sealants are fairly capable of protecting the wood from the harmful UV rays of the sun that can turn the color grayish and do sun damage.