If your business ships goods internationally using wood pallets, crates, or dunnage, understanding heat treatment and ISPM-15 compliance is not optional — it is a legal requirement. Non-compliant wood packaging can result in shipment rejection, quarantine, re-export at your expense, destruction of goods, and fines. This guide explains everything you need to know.
What Is ISPM-15?
ISPM-15 stands for International Standards for Phytosanitary Measures No. 15. It is a regulation created by the International Plant Protection Convention (IPPC), which operates under the United Nations Food and Agriculture Organization (FAO). The standard was first adopted in 2002 and has been revised several times, most recently in 2013.
The purpose of ISPM-15 is to prevent the international spread of wood-boring insects, nematodes, fungi, and other organisms that can devastate forests and agricultural systems. The Asian Longhorned Beetle (Anoplophora glabripennis) and the Emerald Ash Borer (Agrilus planipennis) are two invasive species whose global spread via untreated wood packaging prompted the creation of this standard.
Today, over 180 countries enforce ISPM-15, making it one of the most widely adopted international trade regulations in existence. In the United States, enforcement is managed by USDA APHIS (Animal and Plant Health Inspection Service).
What Materials Are Covered?
ISPM-15 applies to all wood packaging material (WPM) made from coniferous and non-coniferous raw wood used to ship goods between countries. This includes pallets, crates, boxes, dunnage (loose wood used for blocking and bracing), wood used for skids, and any other solid wood thicker than 6mm used in packaging or transport support.
Exemptions apply to processed wood products where the manufacturing process eliminates pest risk. These include plywood, particle board, oriented strand board (OSB), veneer, wood wool, sawdust, shavings, and wood fiber products. These materials do not require treatment or marking under ISPM-15.
The Heat Treatment Process in Detail
Temperature and Duration Requirements
The standard heat treatment protocol (designated HT) requires that the core temperature of the wood reach a minimum of 56 degrees Celsius (132.8 degrees Fahrenheit) for at least 30 consecutive minutes. This temperature must be achieved at the very center of the thickest piece of wood in the treatment load — surface temperature alone is not sufficient.
An alternative method, dielectric heating (DH), uses microwave or radio frequency energy to heat wood from the inside out. Under this protocol, the wood must reach 60 degrees Celsius (140 degrees Fahrenheit) for 1 minute throughout the entire profile, including the surface. DH is faster but requires specialized equipment and is less commonly available.
The Treatment Chamber
Heat treatment is conducted in sealed chambers (kilns) specifically designed for ISPM-15 compliance. These chambers are equipped with calibrated temperature probes that are inserted into the core of representative wood pieces in each treatment load. Automated data logging systems record time and temperature continuously throughout the process.
The entire treatment cycle — from loading through heating, holding, and cooling — typically takes 8-24 hours depending on the wood species, initial moisture content, thickness of the wood, and the capacity of the kiln. Hardwoods and thicker pieces require longer treatment times because heat penetrates more slowly.
Quality Control and Documentation
Every treatment run generates a detailed time-temperature record that must be retained for a minimum of two years. Auditors from the certifying body (in the U.S., the American Lumber Standard Committee — ALSC) can request these records at any time. Treatment facilities are subject to regular audits, typically semi-annually, to verify equipment calibration, record-keeping, and marking accuracy.
The ISPM-15 Stamp Mark
Treated pallets must bear a standardized mark on at least two opposite sides of the pallet. This mark includes the IPPC symbol (a wheat-ear logo), the country code (US for United States), the producer or treatment facility registration number, the treatment code (HT for heat treatment, DH for dielectric heating), and the DB indicator (debarked — required since the 2009 revision).
The mark must be legible, permanent, and not hand-drawn. It is typically applied using a branding iron, ink stamp, or stencil. The mark must not be placed on an easily removable component like a loose board.
Certification and Licensing
In the United States, heat treatment facilities must be licensed by an ALSC-accredited agency. The certification process involves equipment inspection, process validation, operator training verification, and ongoing compliance auditing. Facilities receive a unique registration number that appears on their ISPM-15 marks.
USA Pallet Recycle maintains full ISPM-15 certification at our Goodyear, Arizona facility. We can heat-treat pallets you already own or supply pre-treated pallets for your export needs. Visit our industry standards page for more information about our certifications.
Common Compliance Mistakes to Avoid
The most frequent compliance failures we see include using unmarked or improperly marked pallets for international shipments, assuming all heat-treated pallets are automatically ISPM-15 compliant (the official mark is required), not checking that the treatment facility's certification is current, allowing bark to remain on treated wood (the debarking requirement is strictly enforced), and re-treating pallets without proper marking updates after repair with untreated wood.
If a repaired pallet has any component replaced with untreated wood, the entire pallet must be re-treated and re-marked. This is a frequently overlooked requirement that can cause shipment delays at international borders.
Getting ISPM-15 Compliant Pallets
The simplest way to ensure compliance is to work with a certified provider like USA Pallet Recycle. We can supply new or recycled heat-treated pallets in any standard size or custom dimensions, provide heat treatment services for pallets you already own, and help you navigate the compliance requirements for your specific export markets.