Does Pressure Treated Wood Rot?

Image of a rotting wood fence, but Does Pressure Treated Wood Rot?

Wood rot, which is also referred to as wood decay, is the decomposition of wood due to actions by a specific family of fungi. These microorganisms eat away wood, weakening the structures, resulting in fatal collapsing of buildings and other wooden structures. Pressure treated wood contains chemicals that repel insects such as termites; hence are safe to use underground. One question though, is, does pressure treated wood rot?

Yes, it does rot. Much as there’s chemical infusion during the treatment of wood, it is still susceptible to rot. If you use a pressure treated wood in the exterior environment where it gets rained on without offering a protective coat such as stain, it will rot in the long run. Additionally, the sunlight in the exterior environment facilitates a faster rotting of wood.

If you want your treated wood to last for years when used in the outdoor environment, ensure that you protect it with outdoor furniture stains. Why is staining so important, especially for exterior structures? With no sealant, treated lumber will absorb water and lose moisture; this cycle makes the wood swell and shrink, warp, bend, and crack. After some time, it will start coming apart.

According to a report by the Ohio State University, the materials needed for replacement and repair damage due to decay account for close to 10% of U.S. wood production per year.

That’s why it’s essential to have your pressure treated wood cleaned and coated with a water-repellant every year. You must also remember to inspect your deck regularly for you to identify early signs of deterioration.

Causes of Rot In Pressure Treated Wood

  • Galvanic Rot

If your deck boards are rotting, there could be a few explanations to this. The first one could be due to what we call galvanic rot. It happens when galvanized screws or nails are driven into pressure treated wood. The chemicals that are present in the wood react with the nails resulting in oxidation. This reaction causes corrosion within the wood. There’s only one solution to fixing galvanic rot- removing and replacing the affected lumber from the deck; this would prevent the spreading of the decay.

  • Water Damage

It could be another reason for your deck to rot. Initially, when a deck’s built, only a few contractors pay attention to the surface of the wood. Over time, after the deck is ready, it can bow as the center rises. Alternatively, it will cup and the wood sags. If all the woods are not set similarly, the boards will end up becoming uneven. This effect is usually unnoticeable and can be dangerous. Cupped wood tends to cracks; these cracks allow water to penetrate the wood hence resulting in rot from within quickly.

  • Fungal Infestations

Pressure treated wood can also rot due to fungal issues. Fungi are tiny organisms that get into the wood, increase in numbers, and feed on it with time. The more they continue feeding, the more causes the pressure treated wood continues to decay and soften, which slowly turns into rot.

How Can I Prevent Pressure Treated Wood from Rotting?

To prevent any wood rot on pressure treated wood, you must ensure that it is well covered. There are different finishes like paint, varnishes, oils, waxes, protecting spray, and stains for pressure treated wood that will offer protection and enhance the durability of your treated wood.

Pressure treated wood does crack and develop splits when exposed to water. Getting into contact with water allows fungi to penetrate the cracks and facilitate the rotting of wood. If you own a pressure treated deck, then this is a problem that you will have to live with. The best and the only way to offer protection to your treated wood deck is through the application of preservative. As earlier mentioned, paints, stains, and sealants provide the best options here.

All these preservatives are readily available at the local hardware store. Some of these protectors have fire retardant, which is useful and will help you and your family be safe.

By now, we are all aware that a sealant, for example, provides your pressure treated wood with adequate resistance to moisture damage, which usually leads to rot. However, there’s an added responsibility that comes alongside this as you will need to apply it periodically. Once every single year makes a lot of sense.

You need to know that none of these products come with lifetime protection. A higher grade sealant, however, will guarantee your pressure treated wood prolonged protection; the cost, however, can be a stumbling block. What’s essential is to ensure a constant inspection of your wood so that you can identify signs of wear and tear and keep it coated. This maintenance practice will help keep your treated wood safe from rotting!

One such high-grade sealer that you can use for your pressure treated wood is Ready Seal. This formula is both a stain and a sealer, which gives your structure double protection against elements such as water and sunlight that promote decay.

How To Stain Pressure Treated Wood and Prevent It From Rotting

Staining pressure treated wood is not as complicated as you might have thought. Once you have all the materials that you need for the project, you will find it a walk in the park. Here are some of the essential materials to get you set for staining:

Tools– Scrubbing Brushes, Paint Mixer, Paint Brushes, Power Washer

Formula-Deck Stain/Sealer

  • Step One: Ready Your Formula/Stain

You can decide to go to your local shop or order the stain that you are going to use for your project online. Just ensure that by the time you commence your project, you have the formula ready.

There are so many formulas that you can use for staining. For example, a transparent deck stain has no color; the semi transparent deck stains have a bit more pigmentation that will give a bit of color to your structure.

If your structure is new and just been installed recently, I’d advise you to use a lighter-colored stain. With that, you get the flexibility of applying darker colors later. A darker stain is the best one if you are working with old pressure treated wood because it helps hide the imperfections on the surface.

In cases your deck is located in quite an open space where it receives direct sunlight for most of the day. I’d recommend that you go for a stain with light colors to help reflect the excess heat away. Using dark stain in such cases will only absorb more heat, making it uncomfortable to walk over the deck with bare feet.

  • Step Two: Clean The Pressure Treated Wood/Deck

Unless your wood is new, ensure that you wash it thoroughly. Cleaning helps keep the surface free of dirt, molds, and mildew so that you apply your finish on a clean surface with no contaminants. Once you have washed the wood, give it enough time to dry before going on with the subsequent steps.

There are deck cleaners such as Defy Wood Deck Cleaner that you can use to clean the pressure-treated wood. Use the scrubbing brush to remove grease presents on the surface. You can use the pressure washer in case there are persistent stains.

NOTE: After applying the deck cleaner, ensure that you give it at least 10 minutes to soak into the wood so that it can react to remove all the stains and dirt present on the surface.

Finish off by rinsing your deck using the pressure washer. Ensure that you are working with a pressure of about 1200 PSI to avoid destroying your deck. Allow the deck up to 24 hours of drying time.

  • Step Three: Preparation to Stain Your Pressure Treated Wood

Here are some of the key things that you need to know, even as you prepare to stain your deck.

Do not apply your stain in direct sunlight as it will result in stain drying before absorbing into the wood.

Protect all the vegetation and structures around your working area so that stain does not sprinkle on them. You can use painter’s tape to cover and protect them. 

  • Step Four: Apply the Stain

With your paintbrush, stain all the areas between cracks. Ensure that you apply 1-2 coats of your deck stain. Usually, one layer is enough to do the job just the right way. 

If you are staining pressure treated fence posts, ensure that you start the application from the top working your way down, this applies to all vertical surfaces.

Watch the video below on how to stain treated wood:

How long does Pressure Treated Wood take to rot?

The pressure treatment is so useful that pressure-treated wood is often tipped to stand any potential damage for at least 40 years. If properly maintained, these structures can last half a century or more. As a consumer, there are these things that, if you do, can result in faster rotting of your pressure treated wood. Actions like painting or sealing a pressure-treated too soon before it dries appropriately can result in rotting earlier than expected.


Pressure treatment of wood is one great way of protecting wood against destructive insects that contributes towards rotting. However, this is not enough. If your structure is created using treated timber and is in the outdoor environment, it adds protection by staining and sealing. So…

Does Pressure Treated Wood Rot?

It’s clear from the information in the article that treated wood does rot over time. As a structure owner, it’s your responsibility to maintain your structure, a move that can determine how long your treated wood lasts before starting to rot.   

Several preservative measures can help slow down the rate at which your treated wood rot. They include painting, staining, and the use of sealants. Ensure that you paint or stain your wood after it’s fully dry. Also, prevent the cracks on your treated wood from coming into contact with water. You can do this through painting. With proper maintenance practices, you’d be surprised how long your pressure treated wood lasts.