HT pallets: what heat treated means and what it doesn't
HT means the wood was heat treated to at least 56 °C for 30 continuous minutes through its whole profile, including the core, under ISPM 15. It is a pest-control treatment, not a chemical one. It says nothing about paint, spills or what the pallet carried, so check those separately before reuse.
The standard
ISPM 15's Annex 1 sets the heat treatment schedule for conventional kilns: a minimum of 56 °C for a minimum of 30 continuous minutes throughout the entire profile of the wood, including its core (ISPM 15, 2018 edition). For what each character in an ISPM 15 stamp means, use the stamp decoder at epalrecycling.com.
What HT doesn't tell you
- Whether the pallet was later painted, stained or coated.
- What it carried. A clean HT pallet that held drums of solvent is no longer clean.
- Whether it's someone else's property. Pooled pallets can carry HT marks too; see found a pooled pallet.
- Domestic pallets without a stamp may be untreated or treated; no stamp doesn't mean safe.
For reuse projects
HT plus clean, unpainted, dry wood with no odour is the best starting point for a project. See garden beds and indoor furniture for use-specific advice.
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.