What is heat treatment (HT) for pallets?
Also called: HT, heat treated, ISPM 15 heat treatment
Heat treatment (HT) is the ISPM 15 method of heating wood packaging until the whole profile of the wood, including its core, reaches at least 56 °C for 30 continuous minutes. Treated pallets carry the IPPC mark with the code HT.
In depth: Heat-treated pallets (HT): what they are, when you need them, and cost
HT is by far the most common ISPM 15 treatment for pallets. It uses a conventional steam or dry kiln heat chamber, run on a schedule approved by the national plant protection organization.
The requirement
| Parameter | ISPM 15 requirement |
|---|---|
| Temperature | At least 56 °C (132.8 °F) |
| Duration | 30 continuous minutes |
| Where | Throughout the entire profile of the wood, including its core |
| Mark code | HT |
Treatment providers measure core temperature with sensors in the wood, or use a schedule proven by test runs that link chamber air temperature to core temperature. ISPM 15 says kiln drying and other heat processes count as HT only if they meet these parameters.
Why it matters
HT is required for most export shipments on solid-wood pallets. It can be done on lumber before assembly or on finished pallets. Once treated and marked, a pallet stays compliant for life unless it is repaired or remanufactured.
On a spec sheet or RFQ
Write "ISPM 15 HT, IPPC mark on two opposite sides" (or four, if your customer asks). PDS lists it as "ISPM-15 Compliance: Heat Treatment (HT)". See the heat-treated pallets guide.
Common confusions
HT is not the same as kiln drying to a moisture content. See KD-HT and heat-treated vs kiln-dried. Dielectric heating (DH) is a separate code with different parameters.
Frequently asked questions
What does HT mean on a pallet?
HT is the ISPM 15 treatment code for heat treatment. It means the wood was heated so its core reached at least 56 °C for 30 continuous minutes, under a program approved by the national plant protection organization.
How much does heat treatment add to the price of a pallet?
Industry sources put it at roughly $1 to $3 per pallet in the US (2026 estimate). The cost depends on energy prices, volume and whether the supplier has its own kiln.
Does heat treatment stop mold?
No. Heat treatment kills pests at the time of treatment but does not keep wood dry. Wood can pick up moisture and grow mold afterward, so ask separately for kiln drying to a target moisture content if mold matters.
Is a heat-treated pallet safe for food?
Heat treatment uses no chemicals, which is one reason it is preferred over methyl bromide. Food-contact suitability also depends on cleanliness and the buyer's own requirements.
Related
- GuidesHeat-treated pallets (HT): what they are, when you need them, and costA heat-treated (HT) pallet's wood core was held at 56 °C (133 °F) for 30 minutes under ISPM 15, then stamped with the IPPC mark and HT. Most countries require it on wood pallets crossing their border. It adds roughly $1–3 per pallet (2026 US estimate) and kills pests; it does not dry the wood.
- GlossaryWhat is ISPM 15?ISPM 15 is the International Plant Protection Convention (IPPC) standard for wood packaging material in international trade. It requires pallets, crates and dunnage made of solid wood to be debarked, treated by an approved method such as heat treatment (56 °C core for 30 minutes), and marked with the IPPC mark.
- GlossaryKD-HTKD-HT indicates wood that is both kiln dried (KD), dried to a target moisture content, and heat treated (HT) to ISPM 15. Only HT is an ISPM 15 treatment code; KD describes moisture and does not by itself make a pallet export compliant.
- ComparisonsHeat treated vs kiln dried pallets: what the stamps meanHeat treatment (HT) heats the wood core to at least 56 °C for 30 minutes to meet ISPM 15 for export. Kiln drying (KD) lowers moisture content, typically to 19% or less, to reduce mold, shrinkage and weight. Choose HT for international shipping, KD for moisture control, and KD-HT when you need both.
- GlossaryDielectric heating (DH)Dielectric heating (DH) is an ISPM 15 treatment that heats wood packaging with microwaves or radio waves until the entire profile of the wood, including its surface, reaches at least 60 °C for 1 continuous minute. Treated wood is marked with the code DH.
- GlossaryIPPC markThe IPPC mark is the stamp that shows wood packaging was treated under ISPM 15. It contains the IPPC symbol, a two-letter ISO country code, a producer or treatment provider code assigned by the national plant protection organization, and a treatment code (HT, DH, MB or SF), inside a border.
More in Standards and compliance
- GlossaryCP palletCP pallets (chemical pallets) are a family of nine standardized wood block pallets, CP1 to CP9, developed for the European chemical and plastics industries. Each type has a defined size and construction for loads such as bagged polymer, drums and bulk containers.
- GlossaryDebarked lumberDebarked lumber is wood from which the bark has been removed. ISPM 15 requires all treated wood packaging to be made of debarked wood, allowing only small pieces of bark: under 3 cm wide of any length, or wider pieces with a surface area under 50 cm² each.
- GlossaryEPALEPAL (European Pallet Association e.V.) is the organization that licenses manufacturers and repairers of EPAL Euro pallets and other EPAL load carriers and controls their quality. The EPAL 1 Euro pallet is a 1200 × 800 × 144 mm block pallet used in open pallet exchange across Europe.
- GlossaryFSMA (Food Safety Modernization Act)FSMA is the US Food Safety Modernization Act of 2011. Under its Sanitary Transportation of Human and Animal Food rule (21 CFR Part 1, Subpart O), pallets are transportation equipment and must be designed and maintained so they are suitable and adequately cleanable, and do not make food unsafe.
- GlossaryGMAGMA stands for the Grocery Manufacturers Association (now the Consumer Brands Association), whose name became attached to the standard 48 × 40 in (1219 × 1016 mm) US grocery pallet: a partial four-way wood stringer pallet with three notched stringers, seven top and five bottom deckboards.
- GlossaryGS1GS1 is a global, not-for-profit standards organization that issues company prefixes and maintains the identification and barcode standards used in supply chains, including GTINs for products, the SSCC for logistics units such as pallets, and the GS1-128 barcode.
Last reviewed 2026-09-24. 235 words.