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ISPM 15: Buying Dunnage with Stamp

If your company ships its products overseas then you probably know all about ISPM 15, the heat treatment of wood, and that exporters face consequences for non-compliant wood products. If you're asking yourself "Why do I need to heat treat wood?" you need to read this other Valley Box article.

dunnage in sea container-1

In a nutshell, Heat treatment (HT) is a non-chemical process to prevent the international transport and spread of disease and insects that could negatively affect plants or ecosystems. The process involves heating the wood material until its core reaches 56 °C or 132.8°F for at least 30 minutes. This method of thermal treatment goes beyond the surface to kill any living organisms along with improve resistance to rot and fungus.

Keep in mind the Heat Treatment measure applies to many wood packaging materials but excludes products made from alternative materials such as OSB, hardboard, and plywood.


Mill HT Stamp

HT millThe Heat Treatment Program was developed in order for the American Lumber Standard Committee to implement a quality control program for the official labeling of heat-treated wood material with an ISPM 15 mark. The wood that has been heat treated is marked with an HT stamp, typically from the mill.

When loose lumber is used in conjunction with the wood shipping crate to restrict the movement of products inside the crate it must bear the HT stamp from VBC.

If we cut it into smaller pieces and sell it as loose lumber? Then VBC adds this Stamp every 12".

DUN Stamp


Dunnage is not used inside or on the exterior of any individual wooden box or crate. It is used within a shipping container (40’ or 20’ ISO Containers) to block individual boxes from shifting in transit. When the individual boxes are unloaded from the shipping container, this material is typically left on the floor or discarded.

Example: Dunnage is used to hold a car in place in transport, but the Dunnage is not part of the car.

WPM Stamp

ISPM 15 stamp for dunnage

Wood Packaging Material (WPM) – Wood crate manufacturers will often use certified heat-treated lumber for the construction of their wood packaging materials and apply the proper WPM stamp on the finished product.

Application Requirements: 2 opposite placements.

If a wood package has been constructed with untreated lumber, then the package can be heat treated and stamped by the company that did the treatment.


HT Stamp

HT loose lumberWhen loose lumber is used in conjunction with the wood shipping crate to restrict the movement of products inside the crate it must bear the HT stamp from the manufacturer.


Options to source dunnage with ISPM 15 heat treatment

dunnage in sea container 2Unfortunately, packaging manufacturers are not legally allowed to sell loose lumber featuring their permitted "ISPM 15 HT" stamp.However, Valley Box can sell lumber stamped “ISPM15 HT DUN” indicating dunnage that's been heat treated. There are a few key things to keep in mind:

  • HT Dunnage can only be used to secure and support a commodity but does not remain with the commodity.
  • The use of the Dunnage stamp is always separate from and outside the package and cannot be used in the construction of pallets, boxes, crates or skids.
  • The seller must inform the customer of requirements of its use.
  • If used improperly the agency/inspector must take corrective action with the producer and/or the customer. If not corrected, at a minimum the agency has to inform the producer or customer of any liability of misuse.
  • ISMP 15 identification numbers can be mixed only when dunnage is used to block and brace the wood crate inside a shipping container and is not a part of the construction.

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Need an inspection?

Package Research Laboratory

The United States Department of Agriculture recommends contacting one of the inspection agencies under the Heat Treatment Programs to get information on obtaining officially marked dunnage. Check out Package Research Laboratory they have friendly inspection agents located throughout the United States.
(973) 627-4405

More Inspection Agencies

For a list of inspection agencies and contact information, visit the American Lumber Standard Committee website.Currently there are 19 accredited independent third-party agencies with operations of these agencies extending to approximately 5,300 facilities. They have a convenient contact list on their site.
(301) 972-1700.

Topics: Wood, Tips

Valley Box Company

Written by Valley Box Company

Valley Box demonstrates what is possible beyond just the typical wooden crate. This specialty crating manufacturer works with a wide variety of materials from wood to plastic, corrugated, metals and more. Discover how to take specialty crating to the next level.