Stop Pressure Treated Wood Rot! (EASY Guide!)

Ever wondered if the formidable pressure treated wood in your backyard can stand the test of time and elements? Dive in to unravel the truths!

Does Pressure Treated Wood Rot

Since December 2015, I have owned a deck made of pressure-treated wood. Over time, the deck boards close to the ground have begun to show signs of decay.

So, I did extensive research on how to prevent pressure-treated wood rotting with the help of experts in San Fransisco, CA.

Today with years of experience, I am well aware of this scenario and as a well-experienced woodworker, I’ll tell you how to address this problem without messing things up.

So, let’s find out, does pressure-treated wood rot?

Yes, pressure treated wood can rot over time, especially if exposed to consistent moisture and not properly maintained. The preservatives in the wood help to slow down decay, but they do not make it completely rot-resistant. Regular maintenance and keeping the wood dry are essential to stop pressure treated wood from rotting.

But there’s a lot to know. 

In this article, I’ll explore the reasons for pressure-treated wood rotting, how to stop it, the benefits and drawbacks of pressure-treated wood, and many more.

Furthermore, I’ll answer some frequently asked questions as well.

Stay connected with me at the end. 

Let’s get started!

Pressure treated wood table rotting
Pressure treated wood table rotting

Will Pressure Treated Wood Rot?

Yes, Pressure-treated wood will rot since they are not completely resistant to rot. Several factors can still contribute to its eventual degradation.

Compared to untreated wood, pressure-treated wood is intended to be more rot and decay-resistant. 

During the pressure treatment process, preservatives, such as copper compounds and other chemicals, are impregnated into the wood to prevent the growth of fungi, bacteria, and insects that can lead to wood rot and degradation.

This treatment greatly improves the wood’s resistance to rot-causing moisture and external elements.

Check out, How to Tell if Wood is Rotten!

Signs that the pressure treated wood is rotten
Signs that the pressure treated wood is rotten

What is a Pressure-Treated Wood?

A preservation process known as pressure-treating is applied to lumber to increase its resistance to rot, decay, insect infestation, and other types of deterioration. 

The entire pressure treatment process is carried out in a pressure vacuum to drive the preservatives into the wood pores in place of air.

As a result, the wood is stronger and better suited for outdoor use and structures exposed to dampness and other environmental variables. In addition to copper compounds like copper azole or copper chromium arsenate, pressure-treated wood may also contain other chemicals to increase preservation.

Did you know fact about pressure treated wood rotting
Did you know fact about pressure treated wood rotting

There are various pressure-treated wood grades available. The lumber grades Premium, Select, Number 1, Number 2, and Number 3 are used to advertise pressure-treated wood.

The higher the grade, the fewer obstacles you may face in the future, like less potential to rot.

It isn’t advised to use pressure-treated lumber indoors due to the potential discharge of hazardous chemicals. To use for indoor projects, you can choose untreated wood.

Pressure-treated wood is perfect for applications that may need increased durability or fire resistance such as,

  • Decks
  • Fences
  • Framing
  • Sheds
  • Garden boxes
  • Sandboxes etc.
Pressure treated wood rotting
Pressure treated wood rotting

Why Does Pressure Treated Wood Rot?

Generally, Pressure-treated wood is less likely to decay than untreated wood because it receives a preservative treatment.

But,  It may still rot in some circumstances. Let’s talk about those circumstances in detail.

1. Exposure to Fungi and Microorganisms

If exposed to humidity and other conditions that promote the growth of microorganisms, pressure-treated wood can eventually be infected by fungi or other organisms that cause wood to rot. 

These microorganisms have the potential to damage the wood fibers over time and cause rot.

Usually, fungi or fungal spores damage moist wood. Keeping your pressure-treated wood dry is the simplest approach to stop the harm they do. 

But there are groups of fungi called brown-rot fungi, which damage dry wood too. This kind of fungus can survive with little moisture.

The brown-rot fungus is commonly growing in birch woods and is identified as an uneven pattern or brick-like cracking.

However, compared to wet rotting treated wood, dry pressure-treated wood is generally less prone to rot and can be repaired more easily if it does.

Read to know, How To Get Green Off Pressure Treated Wood!

2. Exposure to Persistent Moisture

Although pressure-treated wood is made to withstand deterioration, moisture can still penetrate it. 

It can nevertheless become saturated and susceptible to rot when exposed to continuous, extended moisture, such as when submerged in water or persistent ground contact. These situations cause a delayed leaching of the preservatives.

3. Chemicals Reactions

As mentioned earlier, pressure-treated wood is wood that has undergone a chemical process that keeps the wood from rotting and makes it resistant to it.

But because they are chemicals, they can still interact chemically with galvanic screws or nails that are inserted into pressure-treated wood which we call galvanic rotting. 

Galvanic rotten wood is typically hard to fix, it requires the replacement of the galvanic nails and screws.

Tip for repairing rotted pressure treated wood
Tip for repairing rotted pressure treated wood

How to Stop Pressure Treated Wood from Rotting?

Now I’m going to share with you the most effective methods to stop your loving pressure-treated wood furniture and woodwork from rotting.

Just keep reading!

1. Seal Your Wood

As the name implies, sealers can seal your surface and can provide an extra layer of protection. 

So, it is an efficient way to increase the durability of pressure-treated wood to rot and decay as well.

These days, you can easily buy pressure-treated wood-specific sealers from the market. It could be paint, stain, varnish, sealant, oil, etc., and can choose according to your particular necessity.

You can also use Flex Seal to fix rotted wood!

Let’s see how to apply a sealer properly on your pressure-treated wood.

You will need the following items.

  • An appropriate sealer
  • A brush, roller, or a sprayer

Now, follow these steps.

1. Ensure that your wood is completely dry and clean

Wood should be dry if it was just purchased. 

If not, let it air dry after buying for a few weeks. Remove any dirt, debris, or mold that may have accumulated by cleaning the wood.

You can use a clean tack cloth or any other alternative for the cleaning process.

Simply you can sprinkle some water on the deck’s surface to determine whether it is entirely dry. 

You can go ahead if the water has completely absorbed into the deck. On the other hand, you must wait longer if the water beads on the deck surface.

2. Apply Sealer

To apply the sealer adhere to the manufacturer’s instructions. Use a brush, roller, or sprayer and apply a generous, equal coat, making sure to cover all areas, including the cut ends.

Some sealants might require pressure spraying. 

To safeguard the quality of your wood surface, make sure the pressure isn’t too high for these. After you’ve finished spraying, remove the moist layer by brushing.

The end grain of the wood should receive extra attention because it is frequently more prone to moisture penetration. To these areas, add more sealer.

3. Allow Drying Time

Allow the sealant to finish drying. Follow the manufacturer’s instructions as drying time frames can vary depending on the product and environmental factors.

4. Apply Multiple Coats If Needed.

Following sealing, you can sprinkle some water on the surface to observe how quickly the water is absorbed by the wood. 

You may need to recoat if it absorbs rather quickly.

Wood sealing is adventitious because sealers are cheap and easily available in even small stores. 

But, the disadvantage includes the reapplication necessary when highly exposed to wear and tear. 

To protect pressure-treated lumber from moisture, you will need to reapply nearly every year.

How to fix pressure treated wood from dry rotting
How to fix pressure treated wood from dry rotting

2. Use of Mildewcides

To further safeguard pressure-treated wood from rot and fungal infestations, use mildewcides, which are substances created to stop or hinder the growth of mildew and other fungi.

Mildewcides are frequently used with wood sealants and preservatives. 

The pressure-treated lumber should be cleaned with mildewcides for best results and then allowed to dry before being coated.

3. Regular Inspection

Even while a sealant offers strong protection against moisture damage, you will need to reapply it from time to time, at least once a year.

Keep your treated wood coated and keep an eye out for signs of wear and tear, mildew, mold, or other fungal growth. Your treated wood won’t rot if you do this!

The structural integrity of the wood might be affected by loose or corroded screws, nails, or other hardware. As necessary, change or tighten them.

Look for any surface damage, such as cracks or splinters. These damages enhance the likelihood of decay by exposing untreated wood beneath the surface.

How to fix pressure treated wood from wet rotting
How to fix pressure treated wood from wet rotting

4. Application of UV stabilizers

To stop pressure-treated wood from deteriorating due to exposure to sunshine and UV rays, UV (ultraviolet) stabilizers are applied to the wood.

They can assist in preserving the wood’s look and structural integrity over time.

UV stabilizers can help maintain the durability and aesthetic appeal of pressure-treated wood while lowering the danger of rotting when used in combination with appropriate wood preservatives, sealers, and routine inspections.

Tip to avoid pressure treated wood from rotting
Tip to avoid pressure treated wood from rotting

How to Fix Rotted Pressure Treated Wood

Pressure-treated wood that has rotted requires removal of the damaged or decayed portions and replacement with sound wood.

Here I’ll show you how to fix rotted pressure-treated wood.

Supplies you will need,

  • Safety gear (gloves, safety glasses, dust mask)
  • Chisel
  • Paint or wood sealer
  • Sandpaper
  • A circular saw

So, let’s discuss the best method in detail to fix rotted pressure-treated wood to avoid it from spreading.

1. Identify the rotted areas

To determine the degree of the rot, thoroughly examine the pressure-treated wood. 

It’s critical to figure out the extent of the rot and whether any structural components are harmed.

2. Remove Rotted Wood

Cut off the rotten areas with a circular saw. Make clean, angular cuts to remove all of the damaged wood. 

If at all possible, reduce to sound, healthy wood. Be careful not to harm any nearby, healthy wood.

3. Prepare Replacement Wood

In order to fill the space left by the removed rotting portions, cut a piece of pressure-treated wood. 

Make sure the replacement wood is coated adequately for outdoor use and has the same dimensions.

Read to know the Best Methods to Protect Outdoor Wood Furniture!

4. Secure the Replacement Wood

Attach the replacement wood to the existing structure using wood screws or nails. Ensure a secure and tight fit.

5. Fill Gaps

Fill up any gaps or seams where the new wood meets the existing structure with wood putty or an appropriate outdoor wood glue.

6. Sanding

To make a surface that is even and smooth, sand the repaired area.

This will make it easier for the repair to blend in with the nearby wood.

Here is a complete guide about Sanding Pressure-treated Wood!

7. Finish and Protect

Apply a suitable finish, such as paint or wood sealant. For the finished product you select, adhere to the manufacturer’s directions.

If you’re unable to find a sealer, better to use bleach to stop wood from rotting!

Pressure treated wood maintenance tips to prevent rottingc
Pressure treated wood maintenance tips to prevent rottingc

How Long Will Pressure-Treated Wood?

Pressure-treated wood can last anywhere for many years, from 10-40 years!

However several factors come to determine the lifespan. Those are,


As mentioned earlier, the lifespan of the wood in water can be greatly increased with routine care, such as resealing or reapplying wood preservatives. 

Timely repairs and routine checks for damage or degradation are crucial.

Wood Type and Lumber Grade

The pressure-treatment chemicals are best absorbed by pine, cedar, Douglas fir, and hem-fir species, which makes them suitable for long-lasting woodwork. 

The most popular types of wood for deck framing are pine and cedar.

There are various grades of pressure-treated wood available, with the “Ground Contact” grade being best suited for uses involving soil or water.

The Ground Contact grade is meant for prolonged contact to dampness and is treated with greater doses of preservatives.

Environmental Conditions

Pressure-treated wood can last for many years in freshwater if it is well cared for. 

Due to salt’s corrosive properties, wood may have a reduced lifespan in locations with saltwater or brackish water.

Rotted pressure treated wood
Rotted pressure treated wood

Advantages and Disadvantages of Pressure Treated Wood

Due to its distinct advantages, pressure-treated wood is a popular choice for outdoor building and landscaping jobs, but it also has certain drawbacks.

Here are some of them.


1. Durability

Pressure-treating the wood increases its resistance to rot, water damage, and insect infestation, extending its lifespan.

2. Protection

Pressure-treated wood can provide protection against moisture, UV radiation, and fungal infestations which is particularly important for outdoor use.

Read, How to Protect Pressure Treated Wood Underground!

3. Affordable

For example, Redwood can cost more because it is naturally more resistant to pressure than other types of wood.

The same durability is possible with pressure treatment but at a lower cost.

4. Versatile

Pressure-treated wood can be cut, painted, stained, and assembled in a variety of ways.


1. Limited Applications

Some pressure-treated wood varieties are unsuitable for all uses because they might have low-level chemical leaching and health risks when used indoors.

2. Environmental Concerns

The use of certain preservatives has raised environmental concerns, and proper disposal is essential.

3. Chemical Exposure

Safety measures are necessary while handling and cutting pressure-treated wood because doing so can expose you to the chemicals used in the treatment.

That’s it, folks! Now you does pressure treated wood rot, reasons for wood rotting and how to stop it.

So, let’s answer some frequently asked questions.


How Long Does Pressure Treated Wood Last Before It Rots?

On average, pressure treated wood can last between 10 to 20 years or even longer, depending on the environmental conditions and the level of care and maintenance it receives. Proper care, including regular inspections and timely repairs, can significantly extend the life of pressure treated wood.

What Causes Pressure Treated Wood to Rot?

Pressure treated wood rots primarily due to fungal issues, which thrive in moist conditions. Keeping the wood dry and well-maintained is crucial to preventing rot and extending its lifespan.

How Can I Prevent Pressure Treated Wood from Rotting?

To prevent rot in pressure treated wood, ensure it is kept dry, apply protective coatings such as paint, oils, or varnishes, and conduct regular inspections to catch and address any signs of decay early on.

Can I Paint Pressure Treated Wood, and Does Paint Prevent Rot?

Yes, you can paint pressure treated wood, but it needs time to dry out before painting. Paint acts as a protective barrier, helping to prevent rot by reducing moisture absorption, but it requires proper preparation and maintenance to be effective.

What Are the Typical Places to Check for Rot in Pressure Treated Wood?

Common areas to inspect for rot in pressure treated wood include deck support posts or beams, exterior window sills, railings, exterior wood stairs, and where wood siding meets trim. Regular inspections in these areas can help identify rot early on.

What Are the Advantages and Disadvantages of Using Pressure Treated Wood?

Pressure treated wood is affordable, durable, readily available, and resistant to the elements, making it a popular choice for outdoor projects. However, it can develop splinters over time, has limited applications, and raises environmental concerns due to the chemicals used in the treatment process.

Are There Environmental Concerns Associated with Using Pressure Treated Wood?

Yes, there are environmental concerns associated with pressure treated wood, particularly related to the chemicals used in the treatment process. These concerns may make pressure treated wood less suitable for eco-conscious consumers.

Can Pressure Treated Wood Be Used Indoors?

While pressure treated wood is generally designed for outdoor use, some types can be used indoors, but it is crucial to choose the right type of pressure treated wood and ensure it is suitable for indoor applications to avoid potential health risks.

How Do I Properly Maintain Pressure Treated Wood?

Proper maintenance of pressure treated wood includes keeping it dry, applying protective coatings, conducting regular inspections, addressing any exposed areas or signs of wear and tear promptly, and using high-quality paints or stains for additional protection.

Did I cover all you wanted to know about: Does Pressure Treated Wood Rot

In this article, I deeply discussed does pressure treated wood rot and how to prevent pressure-treated wood from rotting, and how to stop woods that have already started to rot.

Even though pressure-treated wood has special chemicals to help protect it from bugs, mold, and decay, it can still start to rot after a few years if you don’t cover it with a protective sealer or something to prevent mildew.

Furthermore, I’ve answered some frequently asked questions.

Hope you learn everything you wanted to know about pressure-treated wood rotting including expert tips. 

Now take a scarp pressure-treated wood and practice the methods you learned. Select the best one and use that for your main project! Proper maintenance is the king when it comes to wood durability.

Walter Parker is a woodworking enthusiast. He is passionate about woodworking projects & plays with woodworking tools having spent over 2 decades as a leader for Woodworking Planet. He wants to make people love woodworking! Read More About Him! Follow him on Twitter, Facebook and Linkedin.

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