Pallet Treatment Types - Heat Treatment, Codes & Export Rules

Choosing the right pallet treatment types is essential for ensuring your goods pass through international borders without delay. Because raw wood can harbour invasive species, the International Standard for Phytosanitary Measures No. 15 (ISPM 15) requires that wood packaging material be treated to eliminate pests.

Whether you are looking for heat treated pallets, investigating methyl bromide fumigation, or wondering if kiln dried timber is safe for DIY projects, this guide breaks down the science and regulations behind treated pallets.

What are the Main Types of Pallet Treatments?

There are two primary methods approved under ISPM 15 for wood safety in international trade: heat treatment (HT) and methyl bromide fumigation (MB). These treatments ensure that timber pallets do not carry wood-boring insects or fungi across ecosystems. Other markings you may see on pallets (such as KD, DB, or CT) serve different purposes and are not official ISPM 15 treatment codes.

Heat Treatment (HT)

Heat treatment is the primary method for export pallets today, especially as methyl bromide use is being reduced for environmental reasons. This process involves heating the wood in a specialised chamber until its core reaches a minimum temperature of 56°C for at least 30 minutes.

HT pallets are widely preferred because they do not use toxic chemicals, making them safe to use for transporting food, pharmaceuticals, or for upcycling into furniture. Many export pallets in Australia and North America are now heat treated rather than fumigated with methyl bromide.

Methyl Bromide Fumigation (MB)

Methyl bromide fumigation is a chemical treatment where wood pallets are placed in a sealed chamber and exposed to a pesticidal gas. While highly effective at killing pests present in the wood, methyl bromide is an ozone-depleting substance and is tightly controlled under international agreements such as the Montreal Protocol, hence its phase-out in many regions.

MB remains an accepted ISPM 15 treatment in many countries, even as usage declines. Because these are chemically treated pallets, they are generally not recommended for home use or gardening. If you see the "MB" code on a pallet, it should be handled with caution and never burned.

Kiln Dried (KD)

While kiln dried timber is often confused with heat treatment, they serve different primary purposes. Kiln drying focuses on reducing the moisture content of the wood to prevent warping and mould, whereas HT focuses on sterilisation.

Many pallet suppliers perform both simultaneously; such pallets may be marked KDHT or KD plus an ISPM 15 HT stamp. However, a pallet marked only as "KD" is not automatically ISPM 15 compliant. For export, it must also bear an ISPM 15 mark with "HT" or "MB" to show it has received an approved phytosanitary treatment.

Debarked (DB)

Debarking is a mandatory ISPM 15 requirement for all solid wood packaging material before it undergoes heat treatment or fumigation. This preprocessing step involves removing the outer layer of the log to eliminate primary pest habitats found in the bark and sapwood.

While small bark pieces are tolerated (under 3 cm width or 50 cm² area), the debarking process is essential to enhance treatment efficacy and reduce quarantine risks. The "DB" code is no longer required on new ISPM 15 marks, because debarking is now assumed as part of compliance. You may still see "DB" on older pallets, which remain acceptable if otherwise compliant.

Chemical Treatment (CT)

In the context of logistics and durability, "CT" refers to Chemical Pressure Impregnation (such as copper-based preservatives), sometimes informally marked on pallets. This process is designed for rot and fungi resistance, significantly extending the life of timber pallets in rugged or outdoor environments.

It is critical to note that CT is not an ISPM 15 recognised treatment. Chemical pressure impregnation with preservatives improves resistance to rot and fungi, but it does not substitute for phytosanitary treatment.

Export pallets that are chemically impregnated must still be heat treated or fumigated with MB and carry an official ISPM 15 mark showing "HT" or "MB". Regarding safety, CT wood can off-gas or leach chemicals; avoid cutting or sanding it indoors, and never use it for projects involving direct food or soil contact or for burning.

Understanding Pallet Treatment Codes and Marks

Every treated pallet intended for international shipping must be marked with a permanent, legible stamp known as the ISPM 15 mark (or IPPC mark). This stamp acts as a passport for the wooden packaging, proving it has undergone the necessary treatment method.

On official ISPM 15 export marks, you will only see HT or MB as treatment codes. Other markings like KD, DB, or CT may appear on some pallets, but they are not ISPM 15 treatment codes.

 

How to Read the ISPM 15 Stamp

The stamp includes a two-letter country code (like AU for treated in Australia), a unique registration number for the producer, and the type of treatment applied (HT or MB). If a pallet lacks this stamp, it is likely an untreated wooden pallet intended only for domestic use and is not export compliant.

Untreated wood poses a risk for international shipping because it can lead to heavy fines or the rejection of the entire shipment at the border. Check that the ISPM 15 stamp is present on at least two opposite sides and remains clear and legible; damaged or missing marks can lead to rejection even if the pallet was treated.

Why are Pallets Treated for International Export?

The International Plant Protection Convention (IPPC) developed the ISPM 15 standard to protect global forests. Without these regulations, timber pests like the Emerald Ash Borer could devastate local environments.

Research on invasive forest pests linked to wood packaging shows that preventing these introductions can avoid billions of dollars in long-term damage and management costs. By exposing the wood to high heat or chemicals, pallets are treated to neutralise these biological threats.

Benefits of Using Treated Pallets

• Regulatory Compliance: Ensures your shipping pallets meet international standards when HT or MB is used.
• Durability: Heat-treated and kiln-dried pallets often have lower moisture levels, which helps reduce mould and rot and can improve durability.
• Versatility: HT pallets are ideal for a wide range of industries, including organic food and medicine.

When to use Plastic Pallets

In some cases, you might bypass wood materials entirely. Plastic pallets (and similarly, metal or composite pallets) are naturally exempt from ISPM 15 requirements because the standard covers wood packaging material only. They are a great pallet solution for closed-loop supply chains where hygiene is the top priority.

Which Pallet Type is Right for Your Business?

Choosing the right pallet depends on your destination, budget, and the nature of your goods. While new pallets are the most reliable, recycled pallets that have been re-treated are a cost-effective and sustainable option.

Comparison of Pallet Options

 

Frequently Asked Questions

How can I tell if a pallet is safe for a home garden project?

You can identify safe pallets by looking for the HT (Heat Treated) mark on the ISPM 15 stamp. This code ensures the wood was sterilised using high temperatures rather than toxic pesticides. Always avoid pallets marked with MB, as these were treated with methyl bromide, a hazardous chemical that can leach into soil. Also avoid pallets with CT (chemical treatment) or any unidentified chemical treatments.

Do I need ISPM 15 certified pallets for shipping within Australia?

ISPM 15 is generally required for international exports, not routine domestic deliveries. However, some Australian states and territories have their own biosecurity rules for timber and wood packaging, so you should always confirm requirements for specific routes, especially into high-risk states such as Western Australia, Tasmania, South Australia, and the Northern Territory.

Are plywood and particle board pallets exempt from export treatment rules?

Yes, pallets made entirely from processed wood like plywood, OSB, or particle board are exempt from ISPM 15 requirements. The standard applies to solid wood packaging material thicker than 6 mm; processed wood products undergo high heat and pressure during manufacturing, which naturally eliminates any potential pests. Because they are considered "processed," these pallets do not require a treatment stamp or additional phytosanitary documentation for export.

What is the difference between kiln dried and heat treated pallets?

Heat treatment (HT) is a mandatory sterilisation process for export that kills pests by heating the wood core. Kiln drying (KD) is a seasoning process intended to reduce moisture content to prevent warping and mould. While many pallets undergo both, a "KD" mark alone does not guarantee international export compliance without the accompanying ISPM 15 stamp. Only HT or MB listed within an official ISPM 15 mark indicate export compliance; KD by itself does not.

Can I reuse a heat treated pallet for multiple international shipments?

Yes, you can reuse an ISPM 15 compliant pallet as long as the wood remains intact and the stamp is legible. However, if the pallet is repaired or remanufactured with new wood, it must be retreated and restamped. Any structural changes to the solid wood components invalidate the original certification, requiring a fresh sterilisation process.