Kiln Dried Vs Pressure Treated Lumber! Which Way to Go?

Kiln-drying lumber means the removal of moisture content or water from wood cells. On the other hand, wood pressure treatment refers to air removal from the wood cells and the addition of waterborne preservatives and fire retardants. These processes keep the wood in good shape for a longer duration. Therefore, it would be best to engage in a Kiln Dried Vs Pressure Treated Lumber discussion to determine what works best for you.

Kiln-dried lumber has lower moisture levels that keep the wood fibers from rotting. The wood can also maintain a stain, paint, or varnish finish for longer. Conversely, pressure treated lumber has added compounds such as co-biocide and micronized copper azole. And these components keep the wood’s structure safe from insects, fungal decay, termite attack, and rot.

Let us now dive into a detailed discussion on these two wood preservation methods. Please read till the end for maximum benefit.

What Is the Difference Between Kiln Dried and Pressure Treated Wood?

Kiln dried wood usually undergoes an intense drying process that eliminates water or moisture content from its fibers. On the other hand, pressure treated wood is lumber that has added preservative compounds in its structure.

The primary objective of kiln drying and pressure treating wood is more or less the same. But the processes have different effects on the wood. For example, kiln drying lumber does not change its natural color, unlike pressure treatment which gives the wood a darker green hue.

In addition, kiln-drying reduces the wood’s natural weight significantly. Hence, it is pretty easy to ship the lumber. Conversely, pressure treating wood adds considerable weight levels to the wood.

Kiln dried wood is often crackproof, while pressure treated lumber does not guarantee shrinkage, warping, or splitting resistance. Also, it is fundamental to wait for treated wood to dry before use. Therefore, you may delay your wood project even by a month.

On top of that, kiln-dried lumber comes ready to use. It is easy to work with, lighter, and less likely to split. However, it will cost you a few more coins. So, your budget also determines the wood to get.

Interestingly, most wood dealers prefer to kiln-dry wood before pressure treating it. A lower moisture level helps the lumber absorb the preservatives better. Therefore, it would be best to incorporate both strategies for your wood.

All hope is not gone if you do not have kiln-drying equipment. You can stack the wood on spacers and store it in a dry, shaded, and well-ventilated area. This way, air circulates freely and evenly to dry the wood.

You can cross-cut a sample board to assess whether the wood fibers are dry. Even better, it is possible to frequently check the lumber’s moisture content using a moisture meter. In addition, please note that wood shrinks in all aspects during kiln drying. Thus, it would be best to observe how your boards handle the width and thickness shrinkage.

Is Kiln Dried Wood Good for Outdoor Use?

Yes. Kiln dried wood is good for outdoor use. The lumber has stable moisture content and will not expand or shrink unevenly with varying weather conditions. So, you can have outdoor installations that will not warp or crack.

In addition, kiln dried wood is perfect for decking as it won’t drastically change. Moisture changes can leave an unacceptable gap in your unfinished deck. Therefore, dry wood assures you of a durable project.

However, acclimating the lumber to the project helps, but it will not compensate fully for adverse or extreme humidity changes, including snow, rain, sleet, and air humidity. Thus, it would be best to paint or stain the wood for added protection.

Fortunately, extremely dense hardwoods such as ipe come highly recommended for outdoor projects. They do not absorb excess moisture that causes expansion warping. And they remain intact for a long, long time.

Kiln dried wood keeps you from risks that come with air drying. Remember that the lumber will not shrink or expand. Therefore, you will deliver smooth and stable groove and tongue construction.

Even so, kiln drying lumber is costly and requires skilled labor. In addition, it would be best to keep checking and assessing the wood as it dries. This way, you will identify seasoning defects such as end-splits, internal cracks, warping, and surface checks.

Why We Need to Kiln Dried and Treated Lumber?

It is best to kiln dry and treated lumber as the process delivers even and uniform surfaces. In addition, you can reduce the moisture content as per your project’s requirements. Therefore, it is possible to stop drying once you get the correct level.

Kiln drying wood seasons the lumber perfectly and in a short period, especially if you work under controlled conditions. Also, the timber is usually less liable to shrinkage and remains intact for longer.

The process allows you to use the wood immediately and when you need it. Hence, you do not have to waste any more time before beginning your project. It is also possible to kiln dry the wood from the comfort of your homestead if you have the necessary tools.

Fortunately, kiln drying is not a new procedure in wood production. Instead, it is standard practice for wood processors and production towers. So, you will easily get wood with ‘workable moisture levels’ without much hassle.

Additionally, it is prudent to seal, stain, varnish, and paint dry wood. Otherwise, the wet wood grain will lift the new coat and leave an ugly surface. Therefore, always allow the wood to dry well before further coat application.

The reality of wood’s nature is that it is a hygroscopic material. Therefore, it will always interact with the moisture in the environment unless you fully seal it. In addition, it will release or absorb moisture as necessary to get a balance with the surrounding.

So, wet wood is ultimately susceptible to various problems such as binding and kicking during machining, warping or twisting, or crowning and bulking. Even worse, moisture-related issues can cost you millions of dollars in damages.

Fortunately, kiln drying helps to keep project failures at bay. Therefore, you will enjoy an easy and affordable maintenance routine.

In addition, kiln drying lumber is quite a simple process as all you need to deliver a successful product is an oven (kiln). It helps you to control environmental variables such as humidity, temperature, and steam levels. Thus, you dry the wood to the desired moisture level way faster than air-drying.

It would be best to consider the wood’s hollow and long cell structure. Each board features bundles of long cells that act as pathways to move nutrients and moisture from the roots to other parts. Thus, these paths lose moisture when you cut the tree. And kiln drying aids in drawing out this moisture without damaging the wood.

Pressure treated wood also requires drying before you can use it for your project. More so, green or wet lumber will not deliver satisfactory results for anything from building materials to campfires. 

Though treated wood is perfect for insect and rot resistance, it will not do much good if you do not allow it to dry well. In addition, no paint, stain, or varnish can stick on such a surface.

Also, wet pressure treated wood will crack, warp, shrink, or twist as it dries. Therefore, it is not the best product for flooring, building a deck, or general woodworking applications. Worse still, the lumber may twist or curl if you trim a functional shape.

How Long Will Non Pressure Treated Wood Last Outside?

Non pressure treated wood can last up to five years. But this duration can lengthen or shorten depending on existing climatic and environmental conditions such as humidity, sun exposure, and temperature levels.

You will come across multiple exterior wood structures ranging from picnic tables to wood decks. These projects will remain successful as long as we acknowledge that environmental conditions can be too harsh. Thus, the work may fail sooner than expected.

Thankfully, there are simple protective measures that you can adopt to ensure that exterior wood structures stay durable for a long, long time. So, let’s check a few threats to outdoor wood and how to handle them.

  • Water

Excess water or moisture is a primary enemy to wood fibers. The lumber is vulnerable to almost anything when it gets wet. Even worse, it can start decaying or rotting, and eventually, molds begin to grow on the surface.

However, it is possible to keep the wood safe from water damage. All you need is an outdoor wood sealer. This way, you waterproof the wood’s surface and keep it from water infiltration.

  • Sunlight

Although sunlight has multiple benefits, it can threaten both pressure and non pressure treated lumber. It produces ultraviolet rays that are dangerous to the wood. More so, sunlight drains the wood oil and causes fading and color loss.

You can protect the wood from harmful sunlight exposure by using formulas with UV light blockers.

  • Humidity

Humidity refers to the moisture content in the atmosphere. Therefore, wood in a high humidity environment is prone to mold growth, which eventually causes rot and decay.

  • Climatic condition

Climate and weather affect the wood’s durability. For example, rainy climatic conditions leave the atmosphere with excess moisture levels. On the other hand, dry and sunny places have more sunlight exposure. Both scenarios affect the wood, and it would be best to strike a balance.

  • Unsuitable Wood for Outdoor Use

Wood durability varies with its type. Hence, some woods are highly resistant to elements, while others begin rotting as soon as they soak up water. Also, you’ll find wood species that thrive outside even without treatment.

These woods include cypress, white oak, cedar, and redwood. They have a unique ability and capacity to work well with protective agents like sealers. Therefore, you can easily enhance their durability.

Conversely, woods such as alder, ham lock, and pine are weak. They also feature a higher rotting rate, and it would be best to treat them before outdoor use. Otherwise, you’ll get a failed product within months.

Can You Paint Kiln Dried Wood Immediately?

Yes. You can paint kiln dried wood immediately. However, please check whether the wood is clean before you begin. In addition, conduct the sprinkle water test to ascertain that the wood fibers are moisture-free.

Also, please note that your wood is most likely to be damp unless the lumber yard kiln dries it. Therefore, ensure you check it for dryness. Otherwise, you won’t get a quality finish if you paint too soon.

What Are the Disadvantages of Kiln Drying Timber?

Every good thing usually has a bad side if you do not take care. Similarly, kiln drying has its disadvantages despite presenting a plethora of benefits. For example, the method is costly as you need to get the correct equipment for the job.

The process requires skilled labor. Hence, it would be best to work with or consult an expert if you are a newbie. In addition, kiln drying is quick, and you need to give it continuous attention. Otherwise, you may not notice seasoning defects such as surface cracks, warping, end-splits, and internal cracks.

How Can You Tell If Pressure Treated Wood Is Dry?

Try the ‘sprinkle’ test to tell if your pressure treated wood is dry. Sprinkle water on the lumber and observe what happens. Then, plan to stain or paint the surface if the wood absorbs the water within ten minutes.

On the other hand, give the wood more time to dry if the water pools or beads up on the surface. Otherwise, the paint or stain finish will not adhere to the lumber. Thus, you may incur unnecessary maintenance or repainting costs.

Please note that pressure treated wood comes wet. Wood processors put it under pressure and force chemicals and preservatives into the wood fiber. Therefore, it would be best to check if the lumber is dry before use.

Also, pressure treated wood takes about 72 hours to dry enough for staining or painting projects. So, you can choose to let nature take its course and dry the wood or use the kiln drying process.

Is Stain or Paint Better For Pressure Treated Wood?

Image of kiln dried wood being painted but How Long Can I Wait to Paint After Priming?Professions recommend that it is better to paint pressure treated lumber than painting it. The primary reason is that paint rarely adheres to treated wood because of the pressure treatment process.

However, it would be best to assess if the wood is dry for staining. Otherwise, the wood may reject the stain and waste your money and energy. Also, follow the procedure below to get a perfect stain finish.

  • Test the Wood For Dryness

Pressure treated wood is often wet when you get it from the store. Therefore, it will not absorb the stain properly. But you are free to begin staining immediately if the wood is fresh from the kiln.

Assess the board’s stamp or tag. You are more likely to see ADAT ( air-dried after treatment) or KDAT (kiln-dried after treatment) if it is dry wood. Such lumber is perfect for immediate use. So, wait no further.

In addition, it would be best to use the ‘sprinkle’ technique to check if the wood is dry enough for staining. Sprinkle some water on the lumber’s surface and check how long it takes before absorption.

Wood that needs more time to dry will bead or pool the water on the surface. Thus, it signals that it still has too much moisture in the wood fibers.

  • Wash the Wood 

This step is not mandatory if you have new wood. However, it would be best to wipe the surface with a lint-free cloth before adding a topcoat. On the other hand, please wash already installed wood to remove dirt and debris. This way, the stain will have no interference as it soaks into the wood grain.

You can apply a cleaning solution to loosen up the wood. But let the solution soak in for about ten minutes. Also, adhere to the instructions on the container to get the desired outcome.

Afterward, rinse the surface off with a power washer or garden hose. This way, you’ll easily eliminate tough stains. Then, wait for about 24 hours for the lumber to dry before applying the stain.

  • Prepare the Wood

Prepare the surrounding area with a tarp or painter’s tape to avoid accidental spills on patios, house siding, or furniture. In addition, please sweep the wood to clear off any dirt or leaves that the wood collected during drying.

  • Apply the Stain

Stir the stain well to ensure an even color throughout. Then, pour some on the paint tray and test on a small wood area. Check if you are comfortable with the hue and proceed to stir or apply.

Also, please keep staining the wood until you finish. It would be best to avoid unnecessary breaks as they may compromise the finish. Then, let the formula dry for about 24 hours before walking on it.

That said, it would be best to apply the stain using a paint pad applicator. You can fix it to a pole for easy application. This way, you will deliver enough coverage without having to bend over all the time.

You can also use a brush, but the process can be slow and uncomfortable in wide areas. In addition, you may have to be on your knees most of the time when staining a deck. Therefore, it is wise to use a brush for staining between cracks and hard-to-reach areas.

Even so, it is possible to get a successful product after painting pressure treated wood. So, please check out the instructions below.

  • Ensure the lumber is dry before painting. Then, prepare it as described in the above staining procedure.
  • Use a bristle brush to apply a primer coat on the surface. Also, check if the formula is suitable for pressure treated lumber.
  • Finally, apply two latex paint coats to the surface. You are free to have an additional coat for a sophisticated and durable outcome.

What Happens If You Paint Wet Pressure Treated Wood?

The paint coat will eventually peel off if you paint wet, pressure treated wood. Remember that chemical preservatives in treated lumber minimize its natural vulnerability to rot and insects. However, the process leaves the wood quite wet, which hinders paint adherence.

On top of that, wet wood easily expands and hoards water like a sponge. Hence, the structure contracts and shrinks during drying. Sadly, these expansion and contraction movements cause the wood to warp. And even worse, this scenario cause splits, cracks, and gaps in the paint finish.

Therefore, it would be best always to take your time to assess the wood’s dryness even if you get it straight from the lumber yard. Conduct the sprinkle test and check if the water beads up on the surface.

How Do You Dry Pressure Treated Wood Without Warping?

Image of a warping pressure treated woodThere are two primary strategies to dry pressure treated wood without warping. They include using a wood kiln or laying out the wood flat. The first technique involves drying the wood using a dehumidifying kiln.

On the other hand, the second technique requires you to stack the treated lumber in a criss-cross layout. Then, allow it to air dry for about two to three days. Also, please consider working during warm and low humidity weather.

Fortunately, most decent lumber yards often kiln dry wood for their customers. Therefore, you can get already dried wood from the store if you do not have kiln drying equipment. Even better, you can improvise a kiln drier in your workspace and save money.

Wood stacking or air drying method is easy and highly effective if you follow the correct procedure. Also, it may take longer to deliver a perfect outcome than the kiln drying strategy. But it does not disappoint.


Natural wood is vulnerable to harsh elements such as excess moisture. Hence, woodworkers resort to various strategies such as kiln drying or pressure treating wood to increase the wood’s durability. However, it would be best to understand the two methods before adopting them. So, let’s engage with the topic:

Kiln Dried vs Pressure Treated Lumber

Kiln drying reduces the moisture content in the wood and delivers a crackproof surface. On the other hand, pressure treating lumber includes adding preservatives to the wood to keep it safe from insects and rot.

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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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