Can You Use Non-Pressure-Treated Wood Outside?

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Many homeowners assume that any type of wood can withstand harsh outdoor elements. But the truth is, if you use non-pressure-treated wood outside, it can be exposed to rot, decay, insect infestations, and structural failures.

So, before you take the risk and regret your decision, I’ll dive into the problem and explore the best solution to avoid costly and time-consuming repairs.

How Does Pressure Treatment Affect Wood? Is it Toxic?

Pressure treatment is a process used to protect wood from decay, rot, and insect damage by infusing it with chemical preservatives. 

During the process, the wood is placed in a vacuum-sealed chamber, and pressure is applied to force chemicals into the wood fibers.

The chemicals used in this process can treat wood more durable and resistant to damage, but they can also pose potential health and environmental risks, especially if they are ingested or inhaled.

pressure treated lumbers

The level of toxicity of pressure-treated wood depends on the type of chemicals used, the length of exposure, and the degree of contact. 

So, when working with pressure-treated wood, follow appropriate protective measures to protect yourself in the process.

Pressure Treated vs Untreated Lumber: Which is Which?

Pressure-treated wood is more durable and long-lasting than opting for non-pressure-treated wood, like untreated redwood, spruce, Douglas fir, etc. 

Treated wood requires less maintenance and is suitable for outdoor projects that will be exposed to moisture and insects. However, it is typically more expensive due to the cost of the chemical treatment process.

Untreated lumber, on the other hand, has not been treated with chemicals. It has a natural wood color and appearance and is generally considered safe and environmentally friendly. You can use non-pressure-treated wood for indoor projects.

lumber pressure treated

However, untreated woods are more susceptible to rot, wood decay, and insect damage, and it requires regular maintenance. 

When deciding to choose between treated and untreated wood, it’s important to consider the intended use and environmental conditions. 

How Long Will it Take for Non-Pressure Treated Wood to Last Outdoors?

Generally, you can use non-pressure-treated wood outside for about 2-5 years if it is not maintained or protected from high humidity, heavy rain, or prolonged exposure to sunlight. Also, untreated wood outdoors will not last as long as pressure-treated wood.

Additionally, untreated wood that is exposed to these weather conditions will begin to display indications of deterioration and decay within a few years.

Risks of Using Non-Pressure Treated Wood Outside

UV Radiation

If you leave non-pressure-treated wood outside, it is vulnerable to the rays of ultraviolet radiation and may fade over time. 

deck built with pressure treated wood

The result of this could be the wood losing its natural hue and oils, resulting in a loss of both aesthetics and structural integrity. 

Therefore, sunlight impacts not only the color of wood but also its durability, so applying UV protection is needed.

Water Damage

Non-pressure-treated wood exposed to outdoor conditions is most vulnerable to water damage, which can be caused by snow, rainfall, or other forms of precipitation. 

The water could easily penetrate the pores in natural wood, leading to decay and rot that can rapidly compromise its strength and ultimately result in complete deterioration.

Discoloration (Caused by Molds & Mildew)

Mold and mildew require two simple ingredients to grow: dust and moisture. Even the tiniest amount of these elements in the air can provide enough sustenance for these fungi to thrive. 

mold on wood

This is the reason why untreated wood is prone to developing black spots. However, discoloration is just the beginning of the problem. 

Mold growth can lead to wood rot, which can cause permanent damage to the wood if left unchecked. You might want to know how to remove mold from wood in this guide.

Decrease in Lifespan

Exposure to various weather conditions can weaken the structural stability of untreated wood outdoors, leading to a shorter lifespan. 

Consequently, taking proper care of wooden furniture can significantly extend its lifespan compared to leaving it untreated and not maintaining it adequately while exposed to the elements.

Read Next: How Long Does Pressure-Treated Wood Last Outside?

Insect Damages

If left non-pressure treated wood outdoors, this wood can be rapidly destroyed by insects, particularly termites, which eat the wood. 

termite damaged floor

Without treatment or any protective agents, wood is defenseless and can become an easy target for termites.

Should You Use Untreated Pine Outdoors? How to Protect it Outside?

Utilizing non-pressure-treated pine outdoors is not recommended due to its vulnerability to decay and rot when exposed to moisture and other outdoor elements. 

However, if untreated pine must be used outside, there are several ways exist to protect it and increase its durability.

One effective method is to apply a wood sealant that helps to repel moisture and prevents the wood from absorbing water. 

Applying exterior-grade paint or stain can also help to prevent water damage and provide additional protection against sunlight and other environmental factors.

Pine wood

It’s also essential to keep untreated pine dry and off the ground by placing it on a base of gravel or concrete to prevent moisture absorption from the soil. 

Additionally, I highly recommend covering the wood during heavy rain or snowfall to reduce exposure to moisture and extend its lifespan.

How about Cedar Wood? How Long it Can Last Outdoors?

Cedarwood species are an excellent choice for outdoor use due to their natural resistance to decay and insect damage. It contains natural oils that repel water and insects, making it highly durable and long-lasting when exposed to outdoor conditions.

With proper care and maintenance, cedar wood is a cost-effective and durable option for outdoor spaces or projects because it can last for decades, up to 50 years, or more.

(If you wonder how cedar wood compares to pressure-treated wood, check this article next!)

Is It Advisable to Use Untreated Wood For Outdoor Decks? Will 2x4 Boards Last Outside?

Using untreated wood for outdoor decks is not advisable because it is susceptible to rot and decay when exposed to moisture and other elements. 

lady cleaning deck

Over time, untreated wood can become weak and unstable, posing a safety hazard for outdoor deck use or any other outdoor projects.

2×4 boards are commonly used for decking, but their lifespan outside without treatment is limited that can last up to two years. 

Without any treatment or protection, 2×4 boards can quickly rot and decay, especially if they are in contact with the ground or frequently exposed to moisture. 

Wood Types Ideal for Outdoor Use

Teak deck furniture

Although pressure-treated wood is recommended for outdoor use, there are some wood species that have natural chemicals that can withstand the elements even without treatment. 

The woods listed below can withstand exposure to outdoor harsh elements for extended periods without requiring treatment. Any of these wood types can make natural weather-resistant lumber:

Treating Untreated Wood for Outdoor Use

Tools & Materials

Step #1. Cleaning Your Wood

Before you treat untreated wood, make sure it is clean. If it is heavily soiled with dirt or sticky substances, you will need to use water and soap. 

mixing soap and water

Use a sponge to clean the wood’s surface and remove all dirt, then rinse with clean water and allow the wood to dry completely before continuing. 

If the wood is only slightly dirty, a damp cloth can be used to wipe away dust and grime before allowing it to dry.

Step #2. Sanding

Use sandpaper to smooth out wood surfaces until it’s no longer rough to the touch. The type of sandpaper to use will depend on the project, the wood types, and the sealant used. 

For larger projects such as wooden decks, an orbital sander may be necessary, while a sanding sponge may suffice for smaller projects like a wooden plank. Once you have sanded the wood, use a tack cloth or damp rag to wipe the surface and remove any remaining wood dust. 

Step #3. Applying the Sealant

How to Seal Your Untreated Wood

If you have non-pressure-treated wood that you plan to use outdoors and want to extend its lifespan, I recommend sealing it. Before you seal untreated wood, ensure it is in good condition, showing no signs of initial rot.

sealing the wood

Deck Stain vs. Sealer

Deck stain and sealer products are two different types of coatings. However, they both provide protection and enhance the appearance of wood decks. 

Sealers are clear and protect the wood while preserving its natural beauty. On the other hand, wood stains are colored, available in a myriad of shades, and do double duty: beautifying the wood while also offering protection

man staining deck with Deck Stain Brush Applicator

The choice between the two will depend on your personal preference and the type of wood you’ll be using for the deck.

Step #4: Applying Subsequent Layers

In order to provide sufficient protection, most wood sealing projects require multiple coats of the product. After applying the first coat, allow it to dry for the recommended amount of time.

If three coats are needed, make sure to let the coat dry fully before putting in the next coat. Then, allow the wood to cure before using it.

Can You Weatherproof Non-Pressure-Treated Wood? How?

You can follow these basic instructions to make your wooden items and constructions weather-resistant, regardless of whether they are placed inside or outside. 

These steps are easy to follow and can be done at your own pace:

deck built with pressure treated wood
  1. Begin by applying either tung oil or linseed to the wooden surface. This will create a hand-rubbed finish that is both attractive and protective.
  2. Alternatively, you can use polyurethane, varnish, lacquer finish, or any suitable outdoor wood sealer to achieve a similar result.
  3. If you have non-pressure-treated wood, you can opt for semitransparent deck stains to make it waterproof wood.
  4. To ensure maximum protection, apply a layer of varnish, polyurethane, or lacquer to seal the deck for exterior usage.
  5. Finally, you have the option to utilize a combination of stain and sealant to provide both a finishing and waterproofing effect to the wood at the same time.

Tips for Keeping Non-Pressure-Treated Wood for Outdoor Use

Shelter it from Direct Sunlight

Prolonged exposure to the sun’s ultraviolet radiation [1] can lead to both discoloration and deterioration of the wooden surface. 

inspecting deck

To sidestep potential damage, I recommend shielding wooden pieces from direct sunlight whenever you can.

Keep it Dry

The primary factor behind wood damage and deterioration is moisture, particularly water. 

To avoid this, it’s vital to act quickly when there are liquid spills on your non-pressure-treated lumber. Covering the wood with protective materials to prevent it from being exposed to rain or other sources of moisture is also an essential precaution.

Seasonal Use (Consider the Climate)

If your wooden furniture is made from non-treated wood, I’d advise storing it indoors when not in use, particularly during seasons such as fall, winter, and spring.

Protect it Using Chemicals

To provide your non-treated lumber with the highest level of protection, applying a UV-blocking topical chemical sealant is recommended. 

Conclusion

While non-pressure-treated wood is generally not as durable as pressure-treated wood, you can still use non-pressure-treated wood outside effectively for outdoor projects with proper care and maintenance. 

By following best practices for finishing, sealing, and protecting untreated wood from weather and moisture, you can extend its lifespan and ensure it looks great for years to come!

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Robert Johnson is a passionate furniture maker & carpenter, sought after for his knowledge on the craft.
You’ve probably seen his down-to-earth wisdom in USA Today, Bobvila, Family Handyman, and The Spruce, where he has shared commentary and guidance on various woodworking topics.

Robert is the brain behind Sawinery, where he aims to share tips, tricks, and a passion for all things carpentry.

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