Heat-treated pallets

For regulated solid-wood packaging moving across borders, heat treatment is one approved way to reduce pest risk. The treatment, mark and authorization matter; wood color and the letters “HT” by themselves do not.

When ISPM 15 applies

ISPM 15 addresses wood packaging material used in international trade because raw wood can carry pests. Pallets, skids, crates, dunnage and similar packaging made from regulated solid wood can fall within its scope. The standard does not make every pallet in every shipment subject to treatment.

Packaging made wholly from processed wood products such as plywood, oriented strand board or similar material created with glue, heat or pressure is generally outside the standard’s regulated solid-wood scope. All-plastic and metal pallets are also different materials. Mixed packaging can still contain regulated solid-wood components.

Check the destination, route and current national rules. ISPM 15 is an international standard implemented by national plant-protection organizations. The shipper remains responsible for the requirements that apply to the actual shipment.

What the HT treatment code means

The conventional HT schedule in ISPM 15 requires the wood—including its core—to reach at least 56°C for at least 30 continuous minutes. A treatment facility must use a schedule and monitoring process that achieves that result across the treated wood, not merely heat the air around a pallet.

ISPM 15 also recognizes other treatment codes and schedules, including dielectric heat treatment (DH) and methyl bromide fumigation (MB) under stated conditions. Their availability and acceptability can vary by jurisdiction and facility. Do not rewrite or substitute a treatment code on the pallet.

HT: Conventional heat treatment under the approved schedule.
DH: Dielectric heating under the separate approved schedule.
MB: Methyl bromide treatment under the standard’s schedule and applicable national restrictions.

What a legitimate ISPM 15 mark contains

The official mark combines several elements in a durable, legible, non-transferable format applied by an authorized provider. It normally includes:

the IPPC symbol;
the two-letter country code;
a unique producer or treatment-provider code assigned by the national program; and
the approved treatment code, such as HT.

Marks are normally placed so they are visible, preferably on at least two opposite sides of the wood packaging. Red and orange should be avoided because those colors are associated with dangerous-goods labeling.

This site does not draw a sample certification mark. Inventing a country/provider code can make decorative artwork look like a real authorization. Compare the physical mark with the destination authority or the U.S. program’s guidance.

A mark is a phytosanitary compliance signal. It is not proof of pallet ownership, load capacity, rackability, cleanliness for food use, or safety for furniture and craft projects.

Heat-treated is not the same as kiln-dried

Heat treatment under ISPM 15 is about achieving an approved time-and-temperature schedule to reduce plant-pest risk. Kiln drying is primarily a moisture-reduction process. A kiln schedule may also achieve an approved heat-treatment schedule, but “KD” alone is not the ISPM 15 treatment code and does not replace an authorized mark.

Likewise, heat-treated wood can regain moisture after treatment. The mark does not promise a current moisture content or prevent mold under later wet storage.

Repairs and reused pallets

Reusing a properly marked pallet does not automatically require retreatment if no regulated wood is added and the mark remains valid under the applicable program. Repair, remanufacture and replacement of components can change that status. ISPM 15 and national programs set requirements for obliterating invalid marks, retreating when necessary and applying new marks only through authorized providers.

Do not add an HT or IPPC mark in-house unless the business is authorized under the relevant national program.

Export pallet checklist

Confirm the material. Identify every solid-wood component, including dunnage and blocking.
Check the destination rule. Use the importing country’s current plant-health guidance and your freight or customs professional.
Inspect the mark. It should be legible, durable and tied to an authorized country/provider code and treatment code.
Look for repairs or mixed marks. Replaced boards, multiple conflicting marks or an obscured code need review.
Keep treatment separate from performance. Obtain a separate drawing and rating for the load, handling and support condition.
Check the full shipment. Crates, dunnage, chocks and braces can matter even when the pallet itself is exempt material.

For the broader material and destination workflow, use the export pallet guide.

Primary sources

International Plant Protection Convention, ISPM 15 — regulation of wood packaging material in international trade, treatment schedules and mark requirements.
USDA APHIS — Export wood packaging material — U.S. exporter guidance and program overview.
American Lumber Standard Committee — Wood Packaging Material program — U.S. accreditation and marking program information.

Checked November 14, 2026. Requirements can change; verify the destination before shipment.

Check the destination before loading

A valid treatment mark does not replace the receiver’s size, height, entry or load requirements.

Run a receiving check