Heat treatment (HT)
The ISPM 15 treatment that heats wood to at least 56 °C at the core for 30 minutes.
Heat treatment is one of the approved ISPM 15 treatments for wood packaging. In a conventional kiln, the fundamental requirement is a minimum of 56 °C for at least 30 continuous minutes throughout the entire profile of the wood, including its core.
Pallets treated this way carry HT in their ISPM 15 mark. Heat treatment kills pests without adding chemicals, which is why HT-marked pallets are the usual starting point for DIY reuse.
HT doesn't mean the pallet is clean. It says nothing about later paint, spills or what the pallet carried. See HT pallets for the checks to make before reuse.
Heat treatment is a one-time event at manufacture or treatment; it doesn't stop a pallet picking up contamination later in its working life. Repaired pallets used in export need replacement wood that is itself treated, which is one reason repaired export pallets may carry more than one mark.
Sources
- ISPM 15: Regulation of wood packaging material in international trade (2018 edition) IPPC / FAO. Accessed October 27, 2026. Annex 1: heat treatment (HT) to a minimum of 56 °C for 30 continuous minutes through the whole profile of the wood.