Wood pallets form the backbone of global shipping and logistics, moving billions of dollars worth of goods across oceans, highways, and warehouse floors every single day. Despite their ubiquity, many people in manufacturing, warehousing, and even DIY communities have a surprisingly limited understanding of how these humble wooden platforms are actually made and treated. One of the most frequently asked questions is whether wood pallets undergo pressure treatment — the same chemical-infusion process used on decking, fence posts, and landscape timbers.
The answer matters more than you might think. Whether you are a supply chain manager evaluating pallet specifications, a small business owner preparing goods for international export, or a weekend crafter repurposing pallets into furniture, understanding the treatment history of a wood pallet has direct implications for safety, regulatory compliance, and durability.
What Is Pressure Treatment?
Pressure treatment is an industrial wood preservation method that forces chemical preservatives deep into the cellular structure of lumber. The process begins by placing wood inside a large cylindrical retort, or treatment chamber. Air is evacuated using a vacuum pump, which opens the wood's cell structure and removes trapped moisture and air. Once the vacuum phase is complete, the chamber is flooded with a liquid preservative solution — commonly alkaline copper quaternary (ACQ), copper azole (CA), or, historically, chromated copper arsenate (CCA). High pressure, often ranging from 150 to 200 pounds per square inch, is then applied for an extended period, driving the preservative deep into the wood fibers.
The result is lumber that resists rot, fungal decay, mold growth, and insect infestation far more effectively than untreated wood. This makes pressure-treated lumber ideal for applications where the wood will be in direct contact with the ground, exposed to persistent moisture, or subjected to humid environments. Common uses include outdoor decking, retaining walls, utility poles, and dock pilings.
It is important to understand that pressure treatment is not a surface-level coating. The chemicals penetrate well beyond the outer layers of the wood, often reaching depths of an inch or more. This deep penetration gives pressure-treated wood its long-lasting protective properties but also raises concerns in applications involving food contact, indoor air quality, and material recycling — all of which are highly relevant to the pallet industry.
Are Most Pallets Pressure Treated?
The short answer is no. The vast majority of wood pallets in circulation today are not pressure treated. Industry estimates suggest that well over 90 percent of standard shipping pallets are made from untreated wood.
First, most pallets are constructed from hardwood species such as oak, maple, ash, and birch. These dense hardwoods possess a natural resistance to decay and physical wear that makes additional chemical treatment unnecessary for the typical lifespan of a shipping pallet. A standard hardwood pallet used in domestic freight can endure dozens of trips through supply chains.
Second, cost is a major factor. Pressure treatment adds significant expense — the chemicals are costly, the treatment cycle requires specialized equipment and time, and treated wood must be handled according to strict protocols. A standard pallet might cost eight to fifteen dollars to produce from untreated hardwood. Pressure treating that same pallet could easily add five to ten dollars per unit.
Third, there are regulatory and safety considerations. Many industries, particularly food and pharmaceutical distribution, prefer untreated pallets specifically because they do not contain chemical preservatives that could potentially leach into products.
Common Pallet Treatments
While pressure treatment is uncommon, pallets do undergo other treatment methods widely used in the industry, each serving a different purpose.
Heat Treatment (HT)
Heat treatment is by far the most common treatment method applied to wood pallets, particularly those destined for international shipping. The process involves raising the core temperature of the wood to a minimum of 56 degrees Celsius (approximately 133 degrees Fahrenheit) for at least 30 continuous minutes. This thermal exposure is sufficient to kill insects, larvae, and other biological organisms.
The primary driver behind heat treatment is ISPM-15, the International Standards for Phytosanitary Measures No. 15, established to prevent the international spread of invasive wood-boring pests. Heat-treated pallets carry no chemical residues, making them safe for food contact and environmentally preferable. They are marked with the IPPC stamp, which includes the country code, producer number, and the HT designation.
Chemical Pressure Treatment
Chemical pressure treatment is used on a small subset of pallets where environmental conditions demand enhanced protection — outdoor storage yards, marine environments, tropical climates, or industrial applications involving chemical exposure and standing water. The treatment chemicals used today are predominantly ACQ and copper azole. Pressure-treated pallets are typically stamped with the letters PT.
It is worth noting that pressure-treated pallets are generally not approved for direct food contact. If you encounter a pressure-treated pallet in a food-related environment, it may indicate a compliance issue.
Other Specialized Options
Water-repellent coatings can reduce moisture absorption and warping. Some manufacturers offer hybrid approaches combining heat treatment with a surface-applied fungicide. Methyl bromide fumigation was once widely used but has been phased out in many countries due to its classification as an ozone-depleting substance. Heat treatment has become the de facto standard.
When Pressure Treatment Applies
Softwood pallets are the most common candidates for pressure treatment. Species like pine, spruce, and fir are lighter and less expensive than hardwoods but inherently more susceptible to fungal decay and insect damage. When a softwood pallet will be used in outdoor storage, tropical climates, or marine shipment, pressure treatment can extend its service life from one or two years to five to ten years.
Certain export markets may require pressure-treated pallets due to local regulations or aggressive termite populations. Industrial applications involving chemical exposure present another use case — pallets used in chemical manufacturing or petroleum processing may encounter substances that would rapidly degrade untreated wood.
For standard domestic shipping within the United States, Canada, and most of Europe, pressure treatment is neither required nor recommended. Untreated hardwood pallets or heat-treated softwood pallets meet all regulatory requirements.
How to Identify Pallet Treatment Types
Knowing how to read pallet markings is an essential skill. The most reliable method is to examine the stamps. ISPM-15 compliant pallets carry a distinctive mark including the IPPC logo, a two-letter country code, a producer number, and a treatment code — HT for heat treatment, MB for methyl bromide, or PT for pressure treatment.
Visual cues also help. Pressure-treated wood often exhibits a distinctive green or greenish-brown tint from copper-based preservatives. Over time this fades to silvery gray, but freshly treated lumber is usually easy to spot. Untreated hardwood pallets display natural wood colors — warm browns for oak, lighter tones for maple.
The smell of the wood provides additional clues. Pressure-treated lumber often has a distinct chemical odor, especially when freshly treated or cut. Untreated and heat-treated pallets smell like natural wood.
If you cannot identify a pallet's treatment history from markings or appearance, contact the supplier directly. This is particularly important if you plan to repurpose pallets for indoor furniture, garden beds, or any application involving food contact.
Key Takeaways
Standard wood pallets used in everyday domestic shipping are overwhelmingly made from untreated hardwoods. When treatment is applied, heat treatment is the dominant method, driven by ISPM-15 international shipping regulations. Pressure treatment with chemical preservatives occupies a small but important niche, reserved for pallets facing unusually harsh environmental conditions.
For anyone working with pallets — whether in logistics, manufacturing, or creative repurposing — the ability to identify treatment types through stamps, visual cues, and supplier communication is an essential skill. Always check for the IPPC stamp and treatment code before making assumptions, and when uncertainty exists, err on the side of caution by treating the pallet as potentially chemically treated until confirmed otherwise.
Frequently Asked Questions
No. Industry estimates indicate that well over 90 percent of standard shipping pallets are made from untreated wood. Most pallets are constructed from naturally durable hardwoods like oak and maple that do not require chemical treatment for typical domestic shipping use.
Pressure treatment is reserved for a small subset of pallets destined for harsh environments such as outdoor storage, tropical climates, or marine transport where enhanced rot and pest resistance is essential.
HT stands for heat-treated. This means the pallet was heated to a core temperature of at least 56 degrees Celsius for a minimum of 30 minutes to eliminate insects and biological organisms. Heat treatment is required by ISPM-15 regulations for international shipping.
Heat-treated pallets carry no chemical residues, making them safe for food contact, indoor furniture projects, and garden applications. The HT stamp is part of the IPPC marking that includes a country code and producer number.
It depends on the treatment type. HT-stamped pallets are considered safe for garden use because the heat-treatment process involves no chemicals. Untreated pallets made from natural hardwood are also suitable.
Avoid pallets stamped MB (methyl bromide) or PT (pressure treated with chemical preservatives) for any garden application. The chemicals can leach into the soil and potentially contaminate your plants. If a pallet has no stamp, treat it as potentially chemically treated and avoid using it near food crops.
Look for visual and sensory clues. Freshly pressure-treated wood often has a distinctive green or greenish-brown tint from the copper-based preservatives used in the process. It may also have a noticeable chemical odor, especially when cut.
Check for stamps or tags. Pressure-treated pallets typically carry a PT designation or a tag from the treatment facility identifying the specific chemical and retention level. If you cannot determine the treatment history from markings or appearance, contact the supplier directly.
Heat treatment is preferred for several reasons. It is significantly less expensive than pressure treatment, it introduces no chemical residues into the wood, and it satisfies ISPM-15 international shipping requirements. For most pallet applications, heat treatment provides adequate pest protection without the drawbacks of chemical preservatives.
Pressure treatment adds substantial cost — often five to ten dollars per unit — which is difficult to justify for pallets that may only be used a handful of times. The food safety concerns surrounding chemical residues also make heat treatment the default choice for grocery and pharmaceutical supply chains.
ISPM-15 stands for International Standards for Phytosanitary Measures No. 15, administered by the International Plant Protection Convention. It was established to prevent the international spread of invasive wood-boring pests like the Asian longhorned beetle and the emerald ash borer.
Any wood packaging material used in international trade — including pallets, crates, and dunnage — must comply with ISPM-15. Heat treatment is the most widely accepted compliance method. Pallets that meet the standard carry the IPPC stamp, which customs agencies worldwide recognize as proof of treatment.