Most wood pallets in the US are either untreated or heat treated (HT) - heated until the core of the wood reaches 56 °C (133 °F) for at least 30 minutes to kill pests. They are not pressure treated, and modern pallets are rarely chemically treated; methyl bromide (MB) fumigation is being phased out.
Treatment matters for one main reason: international shipping. Under the ISPM-15 standard, solid wood packaging that crosses a border must be treated and stamped, and a missing or wrong stamp can get the whole shipment held at the port. This guide covers what "treated" actually means for pallets, how to read the stamp (including the hyphen rule US Customs started enforcing in 2026), when you need HT pallets, and what happens to the stamp when a used pallet is repaired.
Key takeaways
- Most pallets are untreated or HT. Pallets are not pressure treated, and chemical fumigation (MB) is increasingly rare.
- HT = pests, not strength or hygiene. Heat treatment kills wood-boring insects; it doesn't make a pallet stronger, cleaner or mold-proof.
- ISPM-15 applies to international shipments - more than 180 countries enforce it. Wood moving between the US and Canada is exempt if it is US- or Canadian-origin; Mexico requires ISPM-15.
- The stamp is the proof. IPPC logo + country code + facility number + treatment code. Since January 1, 2026, a missing hyphen between the country code and the number (US-12345) again makes the mark non-compliant for imports into the US.
- Used HT pallets can be re-exported - but repairs must be done with certified HT lumber by an ALSC-program facility, which removes the old mark and applies its own.
56 °C (133 °F) | 30 min | ISPM-15 | 180+ |
|---|---|---|---|
Minimum core temperature | Minimum time at that temperature | Governing standard | Countries that enforce it |
Are pallets treated?
Some are, most aren't - and "treated" almost never means chemicals. A typical domestic US pallet is untreated lumber. Pallets built for export are heat treated (HT) and stamped under ISPM-15. Pressure-treated wood is not used for pallets, and methyl bromide fumigation is being phased out.
Treatment | Stamp code | Chemicals? | Meets ISPM-15? | Common in the US? |
|---|---|---|---|---|
Untreated | none | No | No | Yes - most domestic pallets |
Heat treated | HT | No | Yes | Yes - the standard for export |
Kiln dried | KD | No | No - not on its own | Lumber often KD; not an export treatment |
Kiln dried + heat treated | KD-HT | No | Yes (the HT part) | Available; good choice for moisture-sensitive loads |
Dielectric heating | DH | No | Yes | Rare |
Methyl bromide fumigation | MB | Yes (fumigant gas) | Yes, but not accepted everywhere | Rare and declining |
Pressure treated (CCA, ACQ, etc.) | - | Yes (preservatives) | No - not an approved treatment | Not used for pallets |
Are pallets treated with chemicals?
Usually not. Heat treatment, the dominant method, uses only heat. The one chemical treatment recognized by ISPM-15 is methyl bromide (MB) fumigation, and it is fading out: the EU does not accept MB-treated wood packaging from the US, and China banned it from January 1, 2020. MB is still permitted in the US, but you'll rarely see it on new pallets. A pallet stamped HT or with no stamp at all was not chemically treated by the manufacturer.
Are pallets pressure treated?
No. Pressure treatment (CCA, ACQ, MCA and similar preservatives) is used for decking, fence posts and ground-contact lumber - not for pallets. It is not an approved ISPM-15 treatment, so it does nothing for export compliance. Pallet wood is not rated for outdoor ground contact; it is packaging lumber built for a limited service life.
Are shipping pallets treated?
Pallets used for international shipping are, almost always by heat treatment, because ISPM-15 requires it. Pallets used for domestic freight usually aren't, since no federal rule requires treatment for shipments that stay in the US. Some food, pharma and electronics buyers still specify HT pallets in their receiving requirements.
What does HT mean on a pallet?
HT stands for "heat treated." The wood was heated until its core reached at least 56 °C (133 °F) and held there for at least 30 continuous minutes, which kills wood-borne pests such as the Asian longhorned beetle, emerald ash borer and pinewood nematode. It is a phytosanitary treatment - not a strength, durability or hygiene claim.
Heat treatment is done in a kiln or heat chamber, either on lumber before the pallet is built or on the finished pallet. It doesn't change the color or smell of the wood in a way you could use to identify it - the stamp is the only proof.
How to tell if a pallet is treated
Look for the stamp. A treated export pallet carries the IPPC mark on at least two opposite sides, usually on the stringers or blocks. The treatment code on the mark - HT, DH or MB - tells you how it was treated.
Stamp with HT or DH: heat treated, no chemicals.
Stamp with MB: fumigated with methyl bromide. Avoid for food loads and for destinations that don't accept MB.
No stamp: treat the pallet as untreated. Even if the lumber was heat treated somewhere along the way, without a legible mark it is not ISPM-15 compliant.
Stamp worn, painted over or broken across a split board: customs treats an unreadable mark the same as no mark.
You can't tell treatment by color, smell or weight. HT wood looks like any other pallet lumber, and weathered untreated pallets can look darker than new HT stock.
What is ISPM-15?
ISPM-15 (International Standard for Phytosanitary Measures No. 15) is the global rule for treating and marking wood packaging material (WPM) so it can't carry pests across borders. It is published by the IPPC (International Plant Protection Convention) under the UN Food and Agriculture Organization and applied by more than 180 countries.
A pallet that doesn't comply can get the entire shipment held, re-exported or destroyed at the port - at the shipper's or importer's expense.
What's covered vs. exempt
ISPM-15 targets raw solid wood, because that's where pests live.
Covered (needs treatment and marking): solid-wood pallets, skids, crates, boxes, pallet collars, reels, and dunnage - the loose lumber used to block and brace cargo in a container.
Exempt - manufactured wood: plywood, OSB, particleboard, fiberboard and veneer, which are produced with heat, glue and pressure.
Exempt - thin wood: ISPM-15 exempts wood 6 mm thick or less; US import rules (7 CFR 319.40-1) exempt wood less than 6 mm thick.
Exempt - non-wood packaging: plastic, metal and corrugated pallets and boxes.
Exempt - domestic shipments: WPM that never leaves the country.
This is why some exporters use plastic or presswood pallets on overseas lanes: they sidestep ISPM-15 entirely. But solid wood is still the cheapest and most available option, and a properly heat-treated pallet is fully compliant - so the decision is usually about cost and supply, not legality.
Approved treatments
Treatment | Code | How it works | Notes |
|---|---|---|---|
Heat treatment | HT | Wood core held at 56 °C for 30+ continuous minutes in a kiln or chamber | Standard method in the US; no chemical residue |
Dielectric heating | DH | Microwave/radio-frequency heating to 60 °C throughout the wood for 1 continuous minute | Faster process, same purpose; uncommon |
Methyl bromide fumigation | MB | Wood fumigated with MB gas in a sealed chamber | Ozone-depleting; not accepted by the EU for US wood packaging, banned by China since 2020 |
Treatment comes first and the mark second - the stamp is the receipt for a process that already happened. You cannot stamp a pallet and treat it later.
Kiln dried is not heat treated
"KD" means kiln dried: the lumber was dried to lower its moisture content, typically below 19%. That alone does not meet ISPM-15 - kiln cycles aren't required to hold the 56 °C core temperature for 30 minutes, and KD lumber doesn't carry an IPPC mark unless it was also heat treated under the program.
The two do different jobs:
HT kills pests but does not protect against mold. Heat treatment can actually draw wood sugars to the surface, and if the pallet later picks up moisture, mold can grow. According to the USDA Forest Products Laboratory, mold develops when the air at the wood surface stays above roughly 80% relative humidity.
KD controls moisture, which is what prevents mold. Dry wood below about 19% moisture content is far less prone to it.
For ocean containers - long transit, temperature swings, condensation - order KD-HT pallets and keep them dry before loading. For storage practices that prevent mold, see storing pallets safely.
How to read the IPPC stamp (HT mark)
The IPPC mark is stamped or branded into the wood - not a sticker - so it can't be peeled off or swapped. A US mark contains:
Element | Example | What it means |
|---|---|---|
IPPC symbol | wheat logo | Signals an official ISPM-15 mark; always on the left |
Country code | US | Two-letter ISO code of the country where the wood was treated |
Facility number | 12345 | The registered producer or treatment facility, assigned under the national program |
Treatment code | HT, DH or MB | The treatment actually applied |
Inspection agency logo | e.g. TP, SPIB, NELMA | The ALSC-accredited agency that audits the facility (US marks) |
Optional codes | KD, DB | KD = also kiln dried; DB = debarked (seen on some marks) |
Put together, a US mark reads like [IPPC logo] US-12345 HT plus the agency logo. It tells you where the wood was treated, who treated it and how.
IPPC pallet markings: HT vs. MB
The treatment code on the official IPPC mark tells you how the wood was treated:
Code | Treatment | What it means for you |
|---|---|---|
HT | Heat treatment - wood core held at 56 °C (133 °F) for at least 30 minutes | No chemicals; accepted wherever ISPM-15 applies |
DH | Dielectric heating - 60 °C throughout the wood for 1 minute | No chemicals; same purpose as HT, uncommon |
MB | Methyl bromide fumigation | Chemical treatment; not accepted by the EU for US wood packaging and banned by China since 2020 - avoid for export and food loads |
The mark itself is defined in the official standard, ISPM 15, Annex 2, published by the IPPC. Only facilities authorized under a national program - in the US, the ALSC program overseen by APHIS - may apply it, and treatment must happen before the mark is applied.
In the US, the ISPM-15 program is run by the American Lumber Standard Committee (ALSC) under APHIS oversight. ALSC accredits inspection agencies, which audit the individual pallet plants and heat-treatment facilities. Counterfeit stamps exist - if a mark looks off, check the facility against ALSC's list of accredited agencies and ask the supplier for their program number.
The 2026 hyphen rule
The ISPM-15 mark requires a hyphen between the two-letter country code and the facility number - "US-12345", not "US 12345" or "US12345". In 2025, APHIS and US Customs and Border Protection (CBP) temporarily suspended enforcement when the hyphen was the only problem with a mark. That suspension ended on December 31, 2025: since January 1, 2026, wood packaging arriving in the US with a non-hyphenated mark can again be treated as non-compliant.
The consequences are the same as for any non-compliant WPM: an Emergency Action Notification, and the shipment is re-exported, treated or destroyed at the importer's expense. CBP can also assess liquidated damages and penalties under its guidelines for non-compliant wood packaging material. If you import on pallets, or ship pallets that will come back to the US, check that your suppliers' stamps have the hyphen.
Sources: APHIS - suspension of ISPM 15 hyphen requirement ends December 31, 2025; CBP Trade Information Notice # 67373551; CBP - wood packaging material.
What is an EPAL pallet?
EPAL is the European Pallet Association, which licenses manufacturers and repairers of the European standard pallet - 1200 × 800 mm (about 47.2 × 31.5 in), a block design with nine blocks. The EPAL logo in an oval is branded on all four corner blocks. Until 2013, the oval also carried the "EUR" mark of the European rail pool, so older pallets of the same design show EUR.
Every EPAL pallet must carry the IPPC HT mark, so a genuine EPAL pallet is always heat treated. In the US, EPAL pallets matter mainly to exporters shipping into European supply chains that expect the 1200 × 800 footprint. For how that size compares to the 48 × 40 GMA pallet, see standard pallet sizes.
When do you need an HT pallet?
Any time solid wood packaging crosses an international border, unless a specific exemption applies. Domestic US shipments don't need HT pallets unless your customer requires them. The main exemption for US shippers is wood packaging made from US or Canadian lumber moving between the US and Canada.
Shipment | ISPM-15 required? | Notes |
|---|---|---|
Domestic US | No | ISPM-15 governs international trade only |
US ↔ Canada | Not for US/Canadian-origin wood | Exemption under 7 CFR 319.40-3 (APHIS) and CFIA D-98-08; wood from third countries must comply |
US to Mexico | Yes | Mexico enforces ISPM-15 (NOM-144-SEMARNAT-2017); USMCA gives no exemption |
US to EU | Yes | HT or DH; MB-treated WPM from the US is not accepted |
US to China | Yes | MB not accepted since January 1, 2020 |
US to Australia / New Zealand | Yes, plus strict conditions | Wood must be practically bark-free; check current import conditions |
Imports into the US | Yes | Hyphenated mark required since January 1, 2026 |
Plywood, OSB, plastic, metal pallets | No | Not solid wood |
Domestic, customer spec (food, pharma) | Customer-driven | A buyer's requirement, not a regulation |
Do you need heat treated pallets to ship to Canada?
Usually not, if the pallets are made from US or Canadian wood. The US and Canada exempt each other's wood packaging made from domestically grown lumber (7 CFR 319.40-3 on the US side, CFIA directive D-98-08 on the Canadian side). Pallets containing wood from any other country must be ISPM-15 treated and marked. Many shippers use HT pallets on Canadian lanes anyway, because the same pallets may continue to other destinations and HT stock removes any question at the border.
What countries require heat treated pallets?
More than 180 countries apply ISPM-15 - effectively every major trading partner, including Mexico, the EU member states, China, Australia and New Zealand. Requirements beyond the standard vary: the EU and China don't accept MB-treated wood from the US, and Australia and New Zealand require wood to be practically bark-free and apply detailed import conditions (published in Australia's BICON database and by New Zealand's MPI). For the official list of national contacts and rules, see the IPPC.
Do heat treated pallets expire?
No. The ISPM-15 mark has no expiration date - a legible HT stamp on an unrepaired pallet is as valid years later as the day it was applied. What can void it is repair with non-compliant wood, or a mark that has worn, split or been painted over until it can't be read.
That makes used HT pallets a good value for export, with two caveats:
Repairs. Under the ALSC program, a repaired HT pallet stays compliant only if it is repaired with certified HT lumber by a facility in the ALSC program. That facility obliterates the old mark and applies its own. A pallet patched with untreated boards - or repaired by someone outside the program - is off the table for export until it is re-treated and re-marked.
Storage. Can heat treated pallets be stored outside? They won't lose their HT status in the rain, but wet HT wood is prone to mold, and rain and sun fade stamps. Store export pallets under cover, off the ground, and keep them separate from your domestic pool so an unmarked pallet never slips into an outbound container.
What happens if your wood packaging fails inspection?
When a CBP agriculture specialist finds non-compliant wood packaging on an import - no mark, an illegible or incorrect mark (including a missing hyphen since 2026), or live pests - CBP issues an Emergency Action Notification (EAN). The importer then has to re-export the shipment, have the WPM treated, or have it destroyed within the set deadline, under CBP supervision and at their own cost. CBP can also assess liquidated damages and penalties.
Other countries apply similar measures to US exports: the shipment is held, treated, re-exported or destroyed, and the cost of delays, storage and handling falls on the shipper or importer - usually far more than the pallets were worth.
How to avoid it:
Inspect the stamp on every pallet, not just the top of the stack. Check for the IPPC logo, "US-" with the hyphen, a facility number and HT.
Buy HT, not MB, unless you have a confirmed reason - HT is accepted everywhere ISPM-15 applies.
Watch repaired stock. Ask used-pallet suppliers whether repairs are done in the ALSC program with certified HT lumber.
Treat dunnage and bracing the same way - they need the mark too.
Keep export pallets dry and segregated from your domestic pool.
Compliance is about the wood, not the grade. ISPM-15 status and condition grade are independent. A grade B used pallet with a legible HT mark and compliant repairs is export-ready; a pristine grade A pallet with no mark is not. For how condition grades work, see pallet grades explained.
Planning an ocean load? See how many pallets fit in a shipping container.
Heat treatment vs. fumigation
Heat is winning. Methyl bromide depletes the ozone layer and is being phased out under the Montreal Protocol; the EU doesn't accept MB-treated wood packaging from the US, and China has banned it since 2020.
Factor | Heat treatment (HT) | Methyl bromide (MB) |
|---|---|---|
Process | Wood core held at 56 °C for 30+ minutes | Chemical fumigation in a sealed chamber |
Chemical residue | None | Fumigant; some buyers refuse MB wood |
Environmental impact | Energy use only | Ozone-depleting gas |
Acceptance (2026) | Accepted wherever ISPM-15 applies | Not accepted by the EU (US wood) or China; declining elsewhere |
Food loads | Suitable | Avoid |
What are fumigated pallets?
Fumigated pallets were treated with a gas - under ISPM-15, methyl bromide, marked MB on the stamp - instead of heat. They are compliant only where MB is still accepted. If you're buying pallets for export, choose HT.
What does an HT pallet cost?
Heat treatment adds a modest premium. For used pallets it is typically $1–3 more per pallet than equivalent non-HT stock; for new pallets, suppliers typically charge 10–20% more (roughly $4–8 on a new 48 × 40).
For reference, the Repackify pallet price index on October 1, 2026 showed average listing prices of $18.81 for a new 48 × 40, $7.90 for grade A used and $6.00 for grade B used (per pallet, all treatment types). Truckload orders usually price lower per pallet than single-pallet listings.
Where to buy heat treated pallets: Repackify connects you with vetted suppliers of new and used HT pallets, including recyclers that repair within the ALSC program - buy pallets.
Are CHEP pallets heat treated?
Not all of them. CHEP says its pallets "can be heat treated" - HT is available, not a default for the whole pool. If you're exporting on CHEP pallets, request ISPM-15-compliant equipment from CHEP and check the mark before loading. CHEP pallets are rented, not bought, so the export rules of CHEP's pooling agreement apply too. See how CHEP pooling works.
Common misconceptions about heat treated pallets
"HT pallets are chemically treated." No. Heat only - no preservatives, insecticides or fumigants.
"HT makes a pallet stronger." No. Strength depends on wood species, board thickness, construction and condition - see our pallet weight and load capacity guide.
"HT pallets are sanitary." Heat kills insects, not dirt or later contamination. A used HT pallet is only as clean as its history.
"HT pallets can't mold." They can. Keep them dry; for moisture-sensitive loads, order KD-HT.
Frequently asked questions
Are pallets treated?
Most wood pallets in the US are either untreated or heat treated (HT). Export pallets must be treated under ISPM-15, almost always by heat. Pallets are not pressure treated, and chemical fumigation with methyl bromide is increasingly rare.
What does HT mean on a pallet?
HT stands for "heat treated." The wood was heated until its core reached at least 56 °C (133 °F) for 30 continuous minutes to kill wood-borne pests, meeting the ISPM-15 international standard.
Are pallets treated with chemicals?
Rarely. Heat treatment uses no chemicals. The only chemical ISPM-15 treatment is methyl bromide fumigation (marked MB), which is being phased out and is not accepted by the EU or China for US wood packaging.
Are pallets pressure treated?
No. Pressure-treated lumber (CCA, ACQ and similar) is not used for pallets and is not an approved ISPM-15 treatment. Export pallets are heat treated.
How can I tell if a pallet is heat treated?
Look for the IPPC mark on two opposite sides: the wheat logo, a country code, a facility number and "HT." If there is no legible mark, treat the pallet as untreated for export purposes.
Do heat treated pallets expire?
No. The ISPM-15 mark has no expiration date. It becomes invalid only if the pallet is repaired with non-compliant wood or outside the ALSC program, or if the mark can no longer be read.
Can heat treated pallets be reused after repair?
Yes, if the repair is done with certified HT lumber by a facility in the ALSC program. That facility obliterates the old mark and applies its own. A pallet repaired with untreated wood can't be exported until it is re-treated and re-marked.
Do I need heat treated pallets to ship to Canada?
Not if the pallets are made from US or Canadian wood - the two countries exempt each other's domestic-origin wood packaging. Pallets with wood from other countries must be ISPM-15 treated and marked.
Does Mexico require heat treated pallets?
Yes. Mexico enforces ISPM-15 for wood packaging from the US under NOM-144-SEMARNAT-2017, and USMCA does not create an exemption.
What happens if the stamp has no hyphen?
The mark must read "US-12345," not "US 12345." APHIS's temporary suspension of this rule ended on December 31, 2025, so since January 1, 2026 wood packaging entering the US with a non-hyphenated mark can be treated as non-compliant: an Emergency Action Notification, then re-export, treatment or destruction at the importer's expense.
What does EPAL mean on a pallet?
EPAL is the European Pallet Association. The EPAL oval mark means the pallet was built or repaired by a licensed EPAL producer to the 1200 × 800 mm European standard. Every EPAL pallet must also carry the IPPC HT mark.
Are heat treated pallets safe for food?
Heat treatment uses no chemicals, so HT pallets are widely used in food and beverage supply chains. But HT is not a sanitation treatment and doesn't prevent mold - for food loads, use clean, dry pallets, preferably KD-HT, and avoid MB-marked wood.
Bottom line
Most pallets are untreated or heat treated - not pressure treated and rarely chemically treated. If your wood packaging crosses a border, it needs a legible ISPM-15 mark with HT (and, for imports into the US, the hyphen), unless you're moving US or Canadian wood between the US and Canada. Used HT pallets are a smart, lower-cost option for export as long as the mark is intact and any repairs were done within the ALSC program. Domestic-only? You don't need HT unless your customer's spec says so.