Guide · Compliance
Heat treatment vs fumigation, and why one of them lost
ISPM 15 permits both. In practice heat treatment has won on safety, cost and acceptance, and methyl bromide is being legislated out of existence.
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Heat treatment (HT) heats wood to a core temperature of 56 °C for at least 30 minutes; methyl bromide fumigation (MB) gasses it with a toxic, ozone-depleting fumigant. Both satisfy ISPM 15, but MB is banned outright by a growing number of importing countries.
For any shipment leaving the United States today, specify HT. RePallet Co. does not offer methyl bromide fumigation and will not source MB-stamped material.
How each works
Heat treatment (HT)
Wood is placed in a chamber or kiln and heated until the core of the thickest member reaches 56 °C, held for 30 continuous minutes. Probes verify core temperature, not air temperature. Pests are killed thermally; nothing is added to the wood.
Dielectric heating (DH)
Microwave or radio-frequency energy heats the wood volumetrically to 60 °C for one continuous minute throughout the profile. Fast and suitable for timber under 20 cm, but capital-intensive.
Methyl bromide (MB)
The wood is sealed and fumigated with methyl bromide gas at a specified concentration and duration. Effective, fast, and an ozone-depleting toxic substance restricted under the Montreal Protocol.
The comparison
| Heat treatment (HT) | Methyl bromide (MB) | |
|---|---|---|
| ISPM 15 compliant | Yes | Yes, where permitted |
| Accepted everywhere | Effectively yes | No — banned by many importers |
| Residue | None | Residual gas; off-gassing required |
| Worker safety | No chemical exposure | Acute toxicity; licensed handling |
| Environmental | Energy use only | Ozone-depleting; Montreal Protocol |
| Effect on wood | Reduces moisture; slight strength gain when dry | None |
| Cost per pallet | $0.60 – $1.60 | Comparable, plus compliance overhead |
| Treatment time | 4 – 12 hours | 16 – 48 hours including aeration |
| Re-treatment after repair | Straightforward | Complex |
| EU / Australia / NZ acceptance | Yes | Restricted or prohibited |
Common misconceptions
"Heat treated means kiln dried"
No. Kiln drying is about moisture content; heat treatment is about a specific temperature-time schedule. A kiln-dried pallet may or may not have met the ISPM 15 schedule. KD-HT means both were achieved, and that is what the mark must say.
"Heat treatment sterilises the wood"
It kills pests present at the time of treatment. It does not prevent re-infestation, mould growth or decay afterwards. Storage conditions after treatment still matter, and a treated pallet left in standing water for a month is a mould problem regardless of its stamp.
"The certificate is what counts"
The mark on the wood is what counts. A customs inspector looks at the pallet, not the folder. A certificate supports the mark; it does not substitute for it.
"Treatment lasts a year"
Compliance does not expire. It is invalidated by modification — adding an untreated board to a treated crate breaks compliance for the whole unit, which is the most common way shipments fail after a transit repair.
What the pests are and why anyone bothers
ISPM 15 can feel like paperwork until you look at what it is actually for. Three insects, each of which arrived in wood packaging and each of which has cost a continent billions.
| Pest | Origin | Arrived in | Impact |
|---|---|---|---|
| Emerald ash borer | East Asia | Wood packaging, North America 1990s | Tens of millions of ash trees killed |
| Asian longhorned beetle | East Asia | Wood packaging, multiple continents | Eradication programmes costing hundreds of millions |
| Pine wood nematode | North America | Wood packaging, Asia and Europe | Devastating to pine forests; drove the EU's rules |
| Citrus longhorned beetle | East Asia | Nursery stock and packaging | Ongoing quarantine responses |
| Bark beetles (various) | Multiple | Bark left on packaging | The reason for bark-free requirements |
The bark-free requirement that catches exporters out is directly traceable to the last row. Several jurisdictions require wood packaging to be free of bark regardless of treatment, because bark harbours insects that the heat schedule may not reach at the surface.
What happens when a shipment fails
Worth knowing before it happens, because the costs are not proportionate to the pallet.
- 1
Inspection at the port
Wood packaging is checked visually. A missing, illegible or non-compliant mark triggers a hold.
- 2
Container held
Demurrage starts accruing, typically per container per day.
- 3
Options offered
Re-treat and re-mark on arrival, replace the packaging, or re-export the container.
- 4
Cost lands on the shipper
Handling, re-treatment, storage, demurrage and the delay. Frequently thousands of dollars.
- 5
Record kept
Repeated non-compliance attracts closer inspection of future shipments from the same shipper.
| Item | Cost |
|---|---|
| Heat treating 26 pallets correctly | ≈ $31 |
| — | — |
| Demurrage, 5 days | $400 – $1,500 |
| Re-treatment or replacement at destination | $600 – $2,200 |
| Handling and re-stuffing | $500 – $1,800 |
| Delay cost to the customer | Varies, often the largest item |
| Typical total | $1,500 – $5,500+ |
Alternatives to treated solid wood
Sometimes the cheapest compliance is not complying, because the material falls outside the standard entirely.
| Material | ISPM 15 | Cost vs. treated wood | Trade-off |
|---|---|---|---|
| Plywood | Exempt | +40% to +90% | Heavier, more expensive, very stable |
| OSB | Exempt | +20% to +50% | Less moisture tolerant |
| Particleboard | Exempt | +10% to +40% | Poor in damp transit |
| Plastic pallets | Exempt | +200% to +800% | Only economic on repeat lanes |
| Corrugated pallets | Exempt | −30% to +20% | Light loads, dry transit only |
| Steel pallets | Exempt | +400%+ | Niche; very heavy loads |
| Presswood / moulded | Exempt | +30% to +80% | Nestable, light, one-way |
For a company shipping a handful of export containers a year, treated wood is almost always the answer. For one shipping weekly on a fixed lane, presswood or plastic can remove the treatment step, the marking risk and the repair-invalidates-compliance problem in one decision.
The hybrid that works
Plywood crate on a presswood or plastic base: entirely outside ISPM 15, dimensionally stable, and no stamp to smudge, miss or invalidate. It costs more per unit and it removes an entire category of failure. For high-value export freight it is frequently the right answer and it is rarely offered.
Questions people actually ask
Is methyl bromide banned?
Does domestic US freight need heat treatment?
Can heat-treated pallets be repaired?
How do I know a pallet is genuinely heat treated?
Is plywood crating exempt?
Does the IPPC mark need to be on pallets moving within North America?
Can I re-use a heat-treated pallet for another export?
What if the stamp has worn off?
Is kiln-dried wood automatically compliant?
Do I need a treatment certificate?
Let's keep your pallets in the loop
Whether you have 40 broken cores behind the dock or need 4,000 Grade A pallets a month, the conversation starts the same way.