As border controls tighten and environmental scrutiny increases on supply chains, one compliance area continues to trip up experienced exporters: wood packaging.
While commercial documentation often receives most of the attention during shipment preparation, the physical packaging itself — pallets, crates, and dunnage — is frequently what triggers inspection holds at borders. When solid wood packaging is not ISPM 15 compliant, the result is not just a compliance query. It can mean delays, rework, and avoidable operational costs that no amount of correct paperwork can fix.
Pallet2Ship, a UK-based pallet shipping platform that has worked with thousands of exporters since 2009, says the problem is rarely that businesses do not know the rules exist. It is that the practical application gets missed in everyday warehouse operations.
“In day-to-day operations, solid wood packaging is one of the most common inspection triggers,” says a spokesperson for Pallet2Ship. “Compliance sits right at the point where your packing decisions, carrier handover, and border clearance all meet. When any of those three slip, you can end up with a shipment sitting in a depot while marks are verified or packaging is reworked.”
The Biosecurity Stakes of Wood Packaging
ISPM 15 (International Standard for Phytosanitary Measures No. 15), developed under the International Plant Protection Convention, exists for a straightforward reason: to stop invasive pests spreading across borders inside untreated timber.
Any solid wood packaging thicker than 6mm used in international trade must be heat-treated, or treated using an approved alternative method, and stamped with an official IPPC mark showing the treatment provider, country code, and treatment type.
On paper, it is simple. In practice, failures happen at the margins — and they happen often.
The Treatment Shift: From Methyl Bromide to Heat
One of the biggest changes in recent years has been the move away from Methyl Bromide fumigation.
MB was widely used for decades but is now heavily restricted globally due to its environmental impact. The industry has shifted toward cleaner and more sustainable treatment methods:
Heat Treatment (HT) — Timber heated to a core temperature of 56°C for at least 30 minutes. This is now the standard method and accounts for the vast majority of compliant pallets in circulation.
Dielectric Heating (DH) — Microwave or radio-frequency treatment, less common but recognised under authorised schemes.
Sulfuryl Fluoride (SF) — A fumigation alternative used in specific regulated contexts, mainly for quarantine or pre-shipment situations.
For most exporters, the practical default is heat-treated pallets stamped with “HT” on the IPPC mark. It is reliable, widely accepted, and avoids much of the environmental baggage associated with older fumigation methods.
Post-Brexit Confusion: What Actually Applies Where
This is where a lot of UK exporters still trip up.
ISPM 15 applies to solid wood packaging in shipments between Great Britain and the European Union. It also applies to shipments from Great Britain to Northern Ireland, because Northern Ireland follows European Union plant health rules under the Windsor Framework.
The requirement does not apply to shipments from Northern Ireland to Great Britain, and wood packaging moving from Northern Ireland to the European Union is treated as intra-European Union trade, so ISPM 15 is not required on that route.
Many exporters assume that because some movements feel “domestic” in practice, ISPM 15 does not apply. That assumption is wrong and can cause problems at consolidation hubs or during carrier inspections.
Another mistake is assuming that because some road freight shipments to the European Union seem to pass without inspection, compliance is optional. Enforcement intensity does vary — by route, carrier, commodity, and inspection point — but the underlying requirement does not change.
For higher-risk destinations like Australia, New Zealand, and the United States, enforcement is stricter. Non-compliance on those lanes more frequently results in holds, rework, and in some cases refusal or destruction of packaging.
Common Operational Failure Points
Pallet2Ship’s detailed compliance guide identifies these as the top four failure points exporters should control:
The 6MM Misunderstanding
ISPM 15 applies to solid wood components thicker than 6mm. Thinner wood is generally exempt — but standard pallets, crates, and timber bracing are almost always well over this threshold. The exemption is relevant for thin backing boards or slats, not for pallets themselves.
The Repair Trap
A pallet can start life fully compliant, stamped and treated correctly. Then someone in the warehouse patches a broken board with a scrap piece of untreated timber. The original stamp is still there, but the pallet is now non-compliant. Ad-hoc repairs using unknown timber invalidate compliance instantly.
Stamp Visibility
IPPC marks must be visible on at least two opposite sides of the pallet. If you wrap the pallet tightly and cover the stamps with stretch film or apply shipping labels over them, an inspector cannot verify compliance. If they cannot see it, they will often treat it as missing.
Last-Minute Dunnage
Everything is packed correctly on a compliant pallet. Then at the last moment, someone adds an offcut of timber to stop something shifting in transit. That piece of wood is now part of the packaging, and if it is not ISPM 15 compliant, the whole shipment can be flagged.
Most of these problems are not deliberate. They happen because decisions are made quickly on the warehouse floor, often by people focused on getting the shipment out rather than checking compliance details.
Exemptions and Alternatives
For businesses that want to reduce wood-related compliance exposure altogether, there are alternatives.
Processed wood products such as plywood, OSB, MDF, and particle board are generally exempt from ISPM 15 because the high-heat manufacturing processes involved in their production destroy pests. Presswood or wood-fibre pallets fall into the same processed wood category and are also outside the scope of ISPM 15.
Plastic and metal pallets also fall outside the scope of the standard because they are not made from raw solid wood.
For some trade lanes, switching to these materials can simplify border compliance while still meeting load-bearing and sustainability requirements.
The trade-off is usually cost. Processed wood and plastic pallets tend to be more expensive upfront than standard heat-treated timber pallets, so the decision comes down to shipment volume, destination risk, and whether the cost of potential delays outweighs the cost of switching materials.
A Practical ISPM 15 Compliance Framework for Exporters
Pallet2Ship has published a detailed ISPM 15 pallet compliance guide that breaks down the controls exporters should build into daily operations. The ten-point checklist covers everything from supplier verification to pre-dispatch photo evidence.
The core advice is straightforward:
- Segregate export pallets from domestic pallets in the warehouse. Do not let them mix.
- Verify stamps before wrapping. Check that the IPPC mark is legible on two opposite sides and includes a valid country code, facility code, and treatment code, usually HT.
- Control all timber additions. Any dunnage, bracing, or blocking added during packing must also be ISPM 15 compliant.
- Take photos before collection. A quick snapshot of the pallet from multiple angles provides evidence of compliance if a query arises later.
- For high-risk routes, use new pallets. Reused pallets can be compliant, but faded marks, hidden repairs, and contamination are more common. For Australia, New Zealand, the United States, or high-value time-sensitive shipments, new heat-treated stock removes uncertainty.
None of this is complicated, but it does require discipline. The best time to catch an ISPM 15 issue is before the vehicle leaves your loading bay. Once it has been collected, your options narrow significantly.
Building Compliance Into Operations, Not Fixing It Later
ISPM 15 compliance is not a paperwork exercise you can sort out retrospectively. It is a warehouse discipline that needs to be built into everyday packing routines.
Treating pallet compliance as part of standard operational control, rather than something to fix after collection, reduces disruption, protects margins, and keeps cross-border shipments moving smoothly.
For businesses moving goods internationally, it is not about ticking a regulatory box. It is about avoiding preventable delays that cost time, money, and customer confidence.
Pallet2Ship’s full ISPM 15 compliance guide, including the practical ten-point export checklist, is available on its website.