ISPM-15 Treatment Codes, IPPC Mark and Exemptions

ISPM 15 is the international standard for wood packaging that crosses a border. Pallets, crates, skids, cable reels and dunnage made of solid wood must be debarked, treated by one of four approved methods, and marked with the IPPC mark. The four treatment codes are HT, DH, MB and SF, and a correct mark with any of them meets the standard.

An MB mark is still a valid mark. ISPM 15 lists methyl bromide as an approved treatment and asks national plant protection organizations to promote the alternatives, and the Montreal Protocol phase-out of methyl bromide exempts quarantine and pre-shipment uses. The EU, Canada and the US all accept MB-marked packaging on imports. Where the fumigation itself may be done is a separate question: EU law allows methyl bromide use inside the EU only under temporary emergency authorizations.

Treatment codes

Code	Treatment	What the standard requires
HT	Heat treatment in a steam or dry kiln chamber	At least 56 °C for 30 continuous minutes through the whole profile of the wood, core included.
DH	Dielectric heating (microwave or radio frequency)	At least 60 °C for 1 continuous minute through the whole profile of the wood, surface included.
MB	Methyl bromide fumigation	A minimum concentration-time dose over 24 hours with the wood at 10 °C or warmer. Not for any piece thicker than 20 cm at its smallest cross-section.
SF	Sulphuryl fluoride fumigation	A minimum concentration-time dose over 24 or 48 hours with the wood at 20 °C or warmer. Not for any piece thicker than 20 cm, or wood above 75% moisture content (dry basis).

Source: ISPM 15, Annex 1 (2018).

Kiln-dried (KD) lumber is dried to a moisture target. A kiln counts as heat treatment only when its schedule meets the HT requirement and the wood is marked HT; a KD grade stamp is not an IPPC mark.

Reading the IPPC mark

The mark is a rectangle or square with the symbol on the left and the codes on the right. ISPM 15 requires all four components:

Component	What it shows
Symbol	The IPPC wheat-ear symbol, to the left of the codes.
Country code	The ISO two-letter code of the country where the mark was applied, joined to the producer code by a hyphen.
Producer or treatment provider code	A code the national plant protection organization assigns to the producer or treatment provider. In the US, the American Lumber Standard Committee (ALSC) runs the program for USDA APHIS.
Treatment code	HT, DH, MB or SF.

Source: ISPM 15, Annex 2 (2018).

A mark reading US-12345 HT was applied in the United States by the producer registered as 12345, on heat-treated wood. Nothing else may sit inside the border. Older marks sometimes add DB for debarked. The current standard requires debarked wood for every treatment, so DB is no longer part of the mark, and importing countries are asked to accept marks made under earlier versions.

The mark must be legible, durable and not hand drawn, and it goes where it stays visible in use, preferably on at least two opposite sides. The standard asks producers to avoid red and orange, the colours of dangerous goods labels.

Bark

Every ISPM 15 package is made of debarked wood, whatever the treatment. Small, separate pieces of bark may remain if each one is either less than 3 cm wide at any length, or wider than 3 cm with a surface area under 50 cm². For MB and SF the bark comes off before fumigation. For HT it can come off before or after.

What ISPM 15 does not cover

The standard exempts these as low risk:

Packaging made entirely of thin wood, 6 mm thick or less.
Packaging made wholly of processed wood made with glue, heat or pressure: plywood, particle board, oriented strand board (OSB) and veneer.
Wine and spirit barrels heated during manufacture.
Gift boxes for wine, cigars and similar goods, made from wood processed to be free of pests.
Sawdust, wood shavings and wood wool.
Wood built permanently into freight vehicles and containers.

Plastic, metal and corrugated packaging are not wood, so the standard does not apply to them. A pallet with solid wood stringers and a plywood deck is still regulated: the solid wood needs treatment, and the mark may go on the plywood where it is easier to see.

Trade between the continental US and Canada has its own arrangement. Canada exempts wood packaging made of US or Canadian wood that comes directly from the continental US.

Repaired and remanufactured pallets

A marked pallet that has not been repaired or altered keeps its mark for its whole service life. A repair changes that, depending on how much was replaced:

Change	What the standard requires
Repaired: up to about one third of the components replaced	Replacement wood is ISPM-15 treated and each added piece carries its own mark, or it is processed wood such as plywood. The country where the repair happens may instead require the old marks removed, the whole unit re-treated and a new mark applied.
Remanufactured: more than about one third replaced	Every old mark is permanently obliterated by painting over or grinding, the whole unit is re-treated, and a new mark is applied.

Source: ISPM 15, section 4.3.

A used pallet with an HT mark on its original stringers and an untreated replacement board does not comply. On Repackify, the seller sets the Heat Treated (HT) field on a pallet listing, so for an export load ask the seller whether the pallets were repaired after they were marked, and for a photo of the mark.

At the border

When an importing country finds packaging without the mark, or finds live pests, ISPM 15 lets it detain the consignment and then remove, treat, destroy or re-ship the packaging. In the US, an inspector at the port of first arrival may order unmarked wood packaging re-exported immediately. In the EU, non-compliant packaging may be destroyed or re-exported and the consignment refused entry, depending on the risk; missing, illegible or incorrect marks were the most common problem EU border checks found in 2023 and 2024.

ISPM-15 compliance guide