Heat-treated pallets with the HT mark for export loads

BOX 01What the HT mark says

ISPM 15 is the international standard that regulates wood packaging material in international trade. It exists so that pests do not travel inside pallets, crates and dunnage. Wood must be debarked first, then either heat-treated or fumigated. Heat treatment means the core of the wood reaches at least 56 °C (133 °F) for at least 30 minutes, per the ISPM 15 summary.

Once the wood is treated, the producer marks it. The mark has four parts: the IPPC logo, a country code, a producer and region number, and a treatment code. HT stands for heat treatment. You can read the mark yourself, step by step, in how to read the HT stamp.

BOX 02Rules that surprise first-time buyers

• Debarked wood. Allowed bark must be under 3 cm wide, or if wider than 3 cm, under 50 square centimeters in surface area.
• Heat treatment is not mold treatment. Pallets loaded into vans while still hot can grow mold. A treated pallet is not immune.
• Canada. Wood packaging coming into Canada from the continental United States is exempt from CFIA policy D-98-08 for now, pending a phased move to full ISPM 15 implementation (CFIA, reviewed 2026). Check before you ship.
• Repairs. A pallet repaired after treatment needs to be treated and marked again for the mark to mean anything.

BOX 03Which loads in Memphis need it

Air freight forwarders near the airport and ocean-bound containers loaded at the river and rail ramps are the common cases; air cargo and forwarding is the clearest. Domestic loads do not need the mark, so there is no reason to pay for it if the freight never crosses a border.

In a request, say yes to heat treatment. Related: export pallets and ISPM 15 for exporters.

BOX 04What to check on arrival

Check the mark on both sides of the pallet, on a stringer or block, where the producer burned or stamped it. A mark that is faint, smeared or painted over is a reason to ask, not to accept. A pallet with the mark but with obvious bark or a damp feel is worth a second look.

Keep treated pallets dry and off bare ground. Treatment does not stop mold, as noted above, so storage still matters in a humid summer. See keeping pallets dry.

BOX 05Wording a heat-treated request

Say yes to treatment, the size, the count, the destination country if you know it and whether the mark has to be visible on a particular face. Forwarders in the airport district often have a specific need, and a plain line saves a round trip. If you are not sure the destination accepts treated wood from a given producer, ask the receiver.

BOX 06Kiln drying is not the same thing

Kiln-dried wood is dried to a moisture level, and heat-treated wood is heated to a core temperature. A pallet can be one without the other, though a pallet that is both is common. For export, the temperature and the time are what ISPM 15 requires, not the dryness. A kiln-dried pallet without the mark is not an export pallet.

The reverse also holds. A heat-treated pallet is not guaranteed to be dry. Wood treated at the mill can be wet again by the time it arrives, and mold needs only moisture and time. Dryness and treatment are separate questions.

BOX 07Questions for a forwarder

• Which countries on this shipment require ISPM 15 wood?
• Do they accept a mark from any registered producer, or only certain ones?
• Does the mark have to be on two sides or only one?
• Is a certificate required in addition to the mark?

Your forwarder knows the answers for your lanes. The pallet supplier knows what the pallet carries. A request needs both.

BOX 08Certificates and what they cover

Some shipments ask for a treatment certificate in addition to the mark. The certificate comes from the producer and refers to a batch. Ask for it when you place a request, not when the load is on the dock, and keep it with the shipping papers.

BOX 09Heat treatment and the pallet's history

A heat-treated pallet that has been repaired with untreated boards is no longer compliant. If you buy used heat-treated pallets for export, ask whether any have been repaired since treatment. A pallet whose boards all show the same mark and the same age is safer.

FAQStraight answers