If you ship internationally on wooden pallets or in wooden crates, your packaging has to clear customs before your product does. The rule that governs it is ISPM-15— International Standard for Phytosanitary Measures No. 15, published by the IPPC (International Plant Protection Convention). It exists for one reason: to stop wood-boring pests like the Asian longhorned beetle and pine wood nematode from hitching a ride across borders inside untreated lumber. A pallet that doesn't comply gets the entire shipment held, re-exported, or destroyed at the port — on your dime.
Key takeaways
- ISPM-15 applies to solid-wood packaging(WPM) used in international trade — pallets, crates, dunnage, blocking, and bracing.
- Compliant wood is treated by heat (HT) to a core temperature of 56°C for at least 30 minutes, or by fumigation (methyl bromide, MB — now being phased out in many regions).
- Proof of treatment is the stamped IPPC mark(the “wheat” symbol) carrying a country code, a producer code, and a treatment code.
- Manufactured wood — plywood, OSB, particleboard — and domestic-only shipments are exempt. Repairing a treated pallet with untreated wood voids compliance.
Who actually needs it
ISPM-15 applies whenever solid-wood packaging material crosses an international border — not when it stays inside one country. So a pallet moving from a warehouse in Ohio to a customer in Texas needs nothing. A pallet leaving the U.S. for Germany, or arriving from China, must be treated and marked. The standard covers the wood that carries or supports the goods, including:
- Pallets— the most common WPM by far
- Crates and boxes built from solid lumber
- Dunnage— the loose wood used to wedge, block, and brace cargo so it doesn't shift in transit
- Skids, pallet collars, and reels made of solid wood
Most countries that trade internationally have adopted ISPM-15, so the practical default for any export is: assume your wood packaging needs to comply unless you've confirmed otherwise for the specific destination.
How wood gets treated: HT vs. MB
There are two recognized treatments. The wood is treated, then marked — the mark is the receipt for a process that already happened. You cannot mark a pallet and treat it later.
| Heat Treatment (HT) | Methyl Bromide (MB) | |
|---|---|---|
| What it does | Heats the wood's core to 56°C for at least 30 continuous minutes, killing pests | Fumigates the wood with methyl bromide gas |
| Treatment code on mark | HT (or DH for dielectric/microwave heating) | MB |
| Status | Standard method, widely used, no chemical residue | Being phased out in many regions over ozone & health concerns |
| Best for | Virtually all modern export WPM | Legacy / specific cases where heat is impractical |
For practical purposes today, heat treatment (HT)is what you'll see and what you should buy. It leaves no chemical residue, doesn't weaken the wood, and is accepted everywhere ISPM-15 is in force. Methyl bromide is restricted or banned for this use in a growing number of regions, so a stack of MB-stamped pallets can be a liability depending on where they're headed.
How to read the IPPC mark
Compliant WPM carries a stamped or branded mark — commonly called the “wheat stamp”because of the symbol next to it. It is not a sticker; it's burned or ink-stamped into the wood so it can't be peeled off or swapped. Every compliant mark has the same components:
| Component | What it means |
|---|---|
| IPPC symbol | The stylized wheat / spike-of-grain logo. Its presence is what signals an official ISPM-15 mark. |
| Country code | Two-letter ISO code for the country where the wood was treated (e.g. US, CN, DE). |
| Producer / facility code | Unique number identifying the certified producer or treatment facility, assigned by that country's plant-protection authority. |
| Treatment code | HT (heat), DH (dielectric heating), or MB (methyl bromide) — the method that was actually applied. |
A complete mark therefore tells you three things at a glance: where it was treated, who treated it, and how. If any of those are missing — or if a pallet has no mark at all — treat it as non-compliant for export purposes.
What's covered vs. exempt
ISPM-15 targets raw solid wood, because that's what pests live in. Wood that has been manufactured through a process that already destroys pests — heat, glue, pressure — is exempt:
- Covered (needs treatment): solid-wood pallets, crates, boxes, dunnage, and bracing.
- Exempt — manufactured wood:plywood, OSB, particleboard, fiberboard, and veneer. These are produced with heat and adhesives, so they don't carry live pests and don't need an ISPM-15 mark.
- Exempt — processed materials: packaging made entirely of metal, plastic, or corrugated cardboard. No wood, no rule.
- Exempt — domestic shipments: WPM that never leaves the country of origin. Treatment is only required for international movement.
This is why many exporters standardize on plastic or pressed-wood (presswood / molded) pallets for overseas lanes: they sidestep ISPM-15 entirely. But solid-wood remains the cheapest and most available option, and a properly heat-treated pallet is fully compliant — so the practical decision is usually about cost and supply, not legality.
Buying compliant pallets
When you source pallets for export, the only thing that matters is the mark. A few habits keep you out of trouble:
- Inspect the stamp on every pallet, not just the top of the stack. Confirm the IPPC symbol, a country code, a producer code, and an HT treatment code are all present and readable.
- Buy HT, not MB, unless you have a specific confirmed reason — heat-treated wood is accepted everywhere and carries no chemical baggage.
- Watch repaired stock.Reused and refurbished pallets are a great value, but any pallet repaired with untreated boards is off the table for export until it's re-treated and re-marked.
- Separate your export pool from your domestic pool. Marked, compliant pallets are worth keeping segregated so an unmarked domestic pallet never slips into an outbound container.
For a deeper walkthrough of the heat-treatment process and what the stamp looks like in the wild, see our heat-treated pallets guide. For everything else about buying and selling pallets — sizes, construction, and reuse — start with the pallets overview.
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Frequently asked questions
Do all wooden pallets need to be ISPM-15 certified?
No — only solid-wood pallets used for international shipments. Pallets that stay within a single country are exempt, and so are pallets made of manufactured wood like plywood, OSB, or particleboard, which are produced in a way that already eliminates pests.
What does the ISPM-15 stamp mean?
The stamp (often called the "wheat stamp") is proof the wood was treated to kill pests. It carries the IPPC wheat symbol, a two-letter country code for where it was treated, a producer code identifying the certified facility, and a treatment code — HT for heat treatment, DH for dielectric heating, or MB for methyl bromide fumigation.
Can I repair a heat-treated pallet and still export it?
Not if you use untreated wood for the repair. A pallet is only compliant if every piece of solid wood in it has been treated. Repairing with an untreated board voids ISPM-15 compliance — the pallet has to be re-treated and re-marked before it can be used for export again.
Is heat treatment or methyl bromide better?
Heat treatment (HT) is the practical choice today. It heats the wood's core to 56°C for at least 30 minutes, leaves no chemical residue, and is accepted everywhere ISPM-15 is in force. Methyl bromide (MB) is being phased out in many regions over environmental and health concerns, so MB-stamped wood can be a liability depending on the destination.