Image of treated wood. So How Long Does Pressure Treated Wood Last?

How Long Does Pressure Treated Wood Last?


Well, wooden equipment needs protection from natural factors such as rotting and pests. Pressure treated wood comes with a top-level of preservation. Any wood that has undergone this process has every chance of defying rot and pests. Even so, how long does pressure treated wood last?

Pressure treated wood offers the best whenever it is used for the outdoor structures. Depending on the prevailing climatic conditions and the level of maintenance practices by the owners, treated wood can last 40 years or more with a guarantee of excellent service life.

So, if you want to get the very best from your pressure treated wood structures for several years, it would be best that you offer the structure a proper and consistent maintenance routine. Keep reading this post for more information on the subject:

Expert woodworkers believe that treated timber lasts a long time. Therefore, if you are in the look for proper construction materials for your home, then consider investing in pressure treated wood. 

According to Forest Products Laboratory and other research agencies, pressure treated poles in the ground can stay up to 40 years without any signs of rot. On the other hand, using pressure-treated wood in making decks or flooring can only last around ten years due to much traffic on the surface compared to the stakes-placed on the ground. 

Note that pressure treatment of the wood only makes it resistant to rot and pests. It does not make the wood resistant to water. Pressure treated lumber, when soaked or splashed with water, gets affected and can lead to the wood cracking, cupping, or bending. You still could prevent that from happening by applying protective layers and coats.

You can ensure the durability of your pressure treated decks by annual application of maintenance dose. Any approved water repellent treatment would work quite well and must be applied all over the surfaces of the wood before installation. 

How Long Do Pressure Treated Fence Posts Last?

Image of fence posts but How Long Do Pressure Treated Fence Posts Last?A properly pressure treated pine fence posts, for example, can exist for a range of 20–35 years if well installed while the untreated one only lasts between 3–7 years. In a case where large numbers are supposed to be installed, it is practical to drive them into the ground using a hydraulic post driver. Ensure that the small end is driven first. 

As I have said before in this article. How well you maintain your treated fence post will determine how long it can serve you. There are several ways of maintaining your wood. Some of the most prevalent ways includes staining and sealing. Formulas that works as stain and sealer in one helps you kill two birds with one stone.

Why Did My Pressure Treated Lumber Rot?

Whenever any treated wood decays, it’s always because of a fungal issue. These fungi are microscopic organisms; they get right into the wood and feed on it as time passes by. This continuous eating of the wood makes it decays, soften, and ultimately turn into rot. Fungi behave the same way with basically all kinds of timber, which results in the same problem.

So what are the factors that facilitate rot and growth of fungi?

Moisture: Presence of moisture in wooden surfaces over extended duration facilitates the growth of fungi which multiply in size to promote the decay of wood.

Pests: There are several pests that eat wood and the most common pet is the termite. These creatures bore holes inside and around wooden structure that allows for water penetration into the wood fibers. Extended presence of water inside the wood can lead to growth of fungi which promotes rotting.

Will Pressure Treated Lumber Rot In Concrete?

Yes, pressure treated lumber can rot in concrete. However, it would take some time for that to happen, and only if the conditions are favorable-wet conditions facilitates rotting. So what exactly makes pressure treated lumber rot? Well, when treated board of wood contacts moisture, damp soil, or water, the chemical used for treatment can leach out of the wood, leaving it vulnerable to fungal activities.

How Do You Keep Pressure Treated Wood From Rotting? 

Pressure-treated wood is a great product to work with because it is less susceptible to damaging elements. However, if not protected, it will rot with time due to constant exposure to moisture and other destructive elements. Therefore, you need to know how to keep your pressure treated from rotting to avoid future issues. 

You can use various methods to protect your pressure-treated wood from rotting, like using paints, stains, oils, waxes, and more. But let’s focus on stains. 

Step 1: Choose your preferred stain.

First, equip yourself with an appropriate stain for the job. If you have old pressure-treated wood, opt for darker stains to help conceal the surface imperfections. But if you have a new one, choose semi-transparent colors as they will add more color to your deck. For the best outcomes, choose oil-based stains because they soak into the wood completely to create a barrier against moisture. 

Step 2: Clean your pressure-treated wood.

Next, be sure to clean your wood thoroughly as any contaminants will prevent the wood stain from adhering as expected. Apply defy wood cleaner to your surface, and let it sit for 3 minutes to act. You then use a scrubbing brush to rub the wood cleaner throughout the surface gently. After that, make a second pass over the surface for more precise results, then rinse your wood with a pressure washer and let it air dry for 24 hours. 

You can also use a soap solution with a pressure washer, especially if your treated wood stays in a shaded place and exhibits signs of fungal growth. 

Note: if you’re dealing with old wood, please take extra steps to remove the stubborn build-up dirt and grime. 

Step 3: Test the stain

Before staining, apply a small portion on your treated wood using your scrubbing brush and allow the stain to adhere properly. Doing this allows you to determine whether the stain has the right shade for your job or not. 

Step 4: Apply the stain.

It’s now time to stain your pressure-treated wood. So take your paintbrush, soak it in a dish containing the stain, then start coating your wood. Avoid using thick coats as they will Dry and crack before you finish coating. Also, don’t stain your wood under direct sunlight, as your stain will dry before soaking up in the wood. 

After the first coat, pull back and check for possible irregularities. If any, fix them and proceed with a second coat for maximum durability. After that, leave the stain to dry according to the operator’s manual. 


Remember that back brushstrokes result in additional coats and can cause color variation. So if you’re staining any vertical surface, begin at the top to ensure you cover any runs as you proceed downwards. 

Also, never stain your pressure treated too soon as the stain won’t get absorbed in the wood fully. 

Safety Tips For Using Pressure-treated Wood

  • Wear a face mask when cutting or drilling treated wood to avoid inhaling harmful dust. 
  • Never burn treated wood as the harmful chemicals in it can present serious health problems. 
  • Don’t use treated woods for any food prep surface because they are not food safe. 
  • Avoid using pressure-treated wood for indoor projects. 
  • Always collect and dispose of sawdust from treated wood. 

How Long Will Pressure-treated 4×4 Last in the Ground? 

Under favorable conditions, a 4×4 pressure-treated wood should last for 20 to 25 years. But this duration can increase to above 40 years if you mount the treated 4×4 wood in a cement ring instead of the soil. 

Several factors can make your 4×4 treated wood degrade prematurely. A good example is humidity. Your pressure-treated wood can easily succumb to humidity if it’s available in excess, wearing down the sealants that protect the 4×4 treated wood from water. So if you live in high humid areas, use other materials apart from wood. 

How Long Does Green Treated Lumber Last? 

Green treated lumber exposed to wet-dry cycles without proper maintenance will only withstand ten years of use. The same lumber will last for more than forty years if you treat it right and practice good maintenance like applying mildewcide cleaner at the first signs of mildew growth.

How Long Will Pressure Treated Wood Stay Green? 

 Pressure-treated wood stays green for about 4 to 6 months. As the wood dries, the green color fades away. So after this duration, it’s recommended that you stain your wood with an appropriate product for added protection and durability. If not, your treated wood will succumb to the destructive elements. 

Can You Stain Pressure-treated Wood Immediately? 

No, staining pressure-treated wood too soon is ineffective as the stain won’t fully penetrate the wood. This means your treated wood will have ugly cracks, splinters, splits, and patches. But if you had already stained too soon, check out these useful tips: 

For light-colored stain

  • Give the wood ample time to dry, then reapply a darker stain as a remedy.

For dark stain

  • Peel down the top layer of stain us8ng medium-grit sandpaper or chemical stain stripper. Then allow the wood to dry before staining again. 

How to Protect Pressure-treated Wood From Naturally Occurring Problems.

Upkeep of your treated wood and other outdoor structures is important as it keeps them in good condition for an extended lifespan. Here are some common problems with pressure-treated wood and how to solve them. 

  • Shrinking and Swelling

The continuous exposure to water can cause your pressure-treated wood to suffer natural defects like warping, twisting, swelling, and more. Luckily you can minimize water movement in and out of your treated wood by applying a coat of semi-transparent deck stain. 

  • Ultraviolet Protection

If you plan to maintain the original color of your pressure-treated wood, you will not only need to clean it regularly but also apply a finish with a UV stabilizer. The UV stabilizer will not completely prevent discoloration but will slow down the process.  

How Can You Maintain Your Treated Wood?

Regular monitoring of your railing, wood deck, fence, and other structures in your yard is critical in keeping your pressure-treated lumber in the best shape possible.

Here are some of the common and naturally occurring problems and how you can protect your wood against them:

Shrinking and Swelling

Constant absorption and loss of water by your pressure treated wood can result in natural deformations such as cupping, warping, twisting, or splitting. You can apply a sealer or opt for a semi-transparent stain for pressure-treated wood to minimize this free movement of water into your wood.

Growth of Mildew

Each time wood gets moist or exposed to humid conditions; there’s an occurrence of mildew growth. So that you don’t experience this less pleasing growth in your pressure treated wood, you’ll have to clean and stain it. Use a cleaner with a mildewcide; this way, your treated wood will retain its brightness and beauty.

UV Protection 

Wood needs protection against UV light. If you are looking to conserve the original color and appearance of your pressure treated wood, then clean your deck periodically. Other than that, apply a water-repellent sealer with an ultraviolet stabilizer. This stabilizer does not entirely prevent eventual discoloration of the wood. However, it slows the process of discoloration.


Until this point, you must be aware that pressure treated wood though offers high resistance to insects and pests, still needs protection and proper maintenance. It is therefore, your responsibility to ensure that you give your structure the very best protection so that it can serve you right for as long as possible. With proper care…

How Long Does Pressure Treated Wood Last?


Pressure treated lumber can last at least four decades. These figures are not fixed because they can last longer than that. What brings the difference and determine how long your wood last is the maintenance practice. Proper care of your treated wood can make it last way more than four decades.

If you have a structure constructed using a treated lumber, ensure that you follow maintenance practices discussed in this article. That way, you will be smiling for as long as you want.

Image of a woodworker wearing hearing protectors for woodworking

Tyron Otieno

Tyron is an avid woodworker and writer. He founded this website to help other woodworkers, whether hobbyists or professionals by sharing his knowledge and experiencie after a decade of woodworking.

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