If you're shipping anything internationally on wood, you've heard "ISPM-15" and probably seen the "HT" stamp burned into a stringer. Here's exactly what it means, when you're legally required to use it, and how to keep a shipment from getting turned away at the port.

What ISPM-15 actually is

ISPM-15 (International Standards for Phytosanitary Measures No. 15) is a global rule that governs wood packaging materials crossing international borders. It exists to stop wood-borne pests — pine beetles, longhorn beetles, wood-boring larvae — from hitchhiking between countries inside pallets, crates, and dunnage.

To meet the standard, the wood has to be treated by one of two approved methods:

HT — Heat Treatment. The wood is heated until its core hits 56°C (133°F) for at least 30 minutes. Most U.S. pallet manufacturers use HT.
MB — Methyl Bromide fumigation. Largely phased out due to environmental rules; almost never used domestically now.

The stamp — what to look for

A compliant pallet carries an IPPC stamp burned (not stickered) into at least two opposite sides. The stamp includes:

The IPPC wheat-sheaf logo
The two-letter country code (US for the United States)
The certified facility's unique number
The treatment method (HT)
Optionally "DB" for debarked

If the stamp is stickered, printed on paper, or missing — the pallet is not compliant. Customs will refuse the load.

When you legally need ISPM-15

You need HT/ISPM-15 pallets when:

The shipment is crossing any international border, including Canada and Mexico in most cases.
You're shipping by ocean container to or from any signatory country (essentially the entire developed world).
Your receiver, broker, or freight forwarder asks for it — most will, automatically, on any export.

You do not need it for purely domestic U.S. shipments, even cross-country. Many manufacturers spec HT pallets for domestic loads anyway, because it simplifies sourcing — they don't have to keep two separate inventories.

What gets a shipment turned away

We've seen all of these cause real problems at the Port of Savannah and inland container terminals:

Missing or unreadable stamp. If customs can't read it, it's not there.
Stamp only on one side. ISPM-15 requires the mark on two opposite sides.
Bark present on a "debarked" requirement. Some countries (Australia, China) require DB (debarked) in addition to HT.
Pallet looks freshly repaired. If a stringer or deck board is obviously newer than the rest, customs may suspect it was patched in after treatment — and reject the load.
Painted-over stamps. Don't paint your pallets after treatment.

Cost and lead time

HT/ISPM-15 pallets typically run a small premium over untreated — the cost is mostly kiln time and certification overhead. Lead time is comparable to standard new-build pallets. We schedule HT runs weekly for Georgia exporters, primarily out of the Savannah and Charleston corridors, and recurring exporters get priority slots.

How to order them

On your RFQ, specify "HT / ISPM-15 stamp required" and let us know the destination country. We'll confirm whether DB is also required and route the order to a stamped facility. If you're not sure, we'll ask your forwarder for you.

Heat-Treated vs Untreated