Do heat-treated pallets expire? No. Heat treatment does not expire simply because an ISPM 15 pallet gets older. A properly treated and marked pallet can remain compliant through repeated trips without being heat treated again, provided it has not been repaired or altered in a way that affects its certification. The pallet must also remain structurally sound, properly marked and free of pest concerns.
A stack of heat-treated pallets has been sitting in the warehouse for several years. The IPPC marks are still visible, the pallets appear sound, but nobody can remember when they were purchased. Are they still acceptable for international shipping, or does heat treatment eventually expire?
The date on the calendar isn’t what determines whether an older HT pallet can make another international trip. USDA APHIS states that the intent of ISPM 15 is that treatment does not expire, while Canada’s certification program likewise allows compliant, unaltered wood packaging to be reused and re-exported without retreatment.
Heat treatment doesn’t expire, but pallets do wear out
ISPM 15 treatment addresses the phytosanitary risk associated with pests that may be present in raw wood packaging when it is treated. It isn’t a coating or preservative that gradually wears off.
The pallet itself, however, remains a working piece of material-handling equipment. Years of forklift impacts, weather exposure and repeated trips can leave it with broken boards, split stringers, damaged blocks, protruding fasteners or other problems that make it unsuitable for another load. Our guide to when a wood pallet should be taken out of service looks more closely at those warning signs.
The IPPC mark can deteriorate as well. For wood packaging entering Canada, CFIA requires the ISPM 15 mark to be legible and considers illegible marks noncompliant. See What If the IPPC/ISPM 15 Stamp on a Pallet Is Unreadable?
So an older pallet may have a treatment that hasn’t expired while still being a poor choice for an export shipment.
Repairs change the question
This is where the distinction becomes important. A pallet that has simply been reused isn’t the same as one that has been repaired. Canada’s Heat Treated Wood Products Certification Program states that ISPM 15-compliant wood packaging that hasn’t been repaired or altered may be reused and re-exported without retreatment. It also lays out specific requirements when components have been replaced and the certification is to be maintained.
Current U.S. APHIS guidance is more straightforward for U.S.-certified wood packaging material: repaired or remanufactured wood packaging must be treated again, the old mark obliterated and a new mark applied through the accredited system. Our guide, Does a Repaired ISPM 15 Pallet Need to Be Heat Treated Again?, looks more closely at the difference between the Canadian and U.S. approaches.
That makes the history of an older pallet more important than its age. If a pallet has been sitting in your own controlled inventory, with clearly legible markings and no evidence of repair, its history may be relatively easy to establish. A used HT pallet of unknown origin deserves a closer look. New-looking replacement boards, multiple marks or evidence of previous repairs are reasons to investigate rather than simply relying on the original stamp.
The same considerations apply when buying previously used export pallets. See Should I Buy Used Heat-Treated Pallets for International Shipping?
Treatment doesn’t provide permanent pest protection
There is one other misconception worth avoiding. A valid HT mark doesn’t mean that the pallet can never encounter pests again. Wood packaging entering the United States must be pest-free as well as appropriately treated and marked, and APHIS inspectors look for signs including insects, feeding damage, exit holes and frass.
Storage conditions therefore still matter. A pallet that has spent years outside in poor conditions shouldn’t get a free pass simply because it carries an IPPC mark. Moisture can also create other problems for wood pallets, including mold. See What’s the Best Way to Store Wood Pallets Outside? for practical storage guidance.
What should you check before reusing an older HT pallet?
For an older HT pallet, the practical inspection is straightforward: check the IPPC mark, look for repairs or alterations, inspect the pallet’s structural condition and make sure there are no signs of pests or contamination.
The treatment doesn’t expire. The pallet still has to remain compliant and fit for the trip.
Find answers to more questions about ISPM 15, export pallets, pallet repair, storage and reuse at our Pallet Problems hub.
Have a pallet problem we haven’t covered? Send us your question. We may answer it directly or use it as the basis for a future Pallet Problems article.
Rick LeBlanc, EMBA, is the founder and editor of Reusable Packaging News (subscribe to the free newsletter) and editor of Western Pallet Magazine. A supply chain journalist with more than 30 years of experience, he specializes in pallets, reusable packaging, material handling and related operations. Rick is co-author of Pallets: A North American Perspective and Pallets & Progress: A Collected History of Pallets and Palletized Handling 1922–1945. He is also an advisory board member of the Virginia Tech Center for Packaging and Unit Load Design. Read Rick’s full bio.
