--- title: "Reefer Liner Delamination and When a Box Needs Relining" description: "A refrigerated box loses efficiency long before the liner looks bad. Here is how reefer liner delamination starts, how to find it and when relining is the answer." canonical: https://ocrv.xyz/library/blog/reefer-box-liner-delamination/ business: "OCRV Center" phone: "(949) 799-3387" address: "23281 La Palma Ave, Yorba Linda, CA 92887" market_served: "West Covina, California" --- # Reefer Liner Delamination and When a Box Needs Relining Published 2026-02-12. Reefer liner delamination starts as a soft spot behind an intact surface, usually low on a sidewall or at a seam. Once the bond releases, moisture reaches the foam core and insulation value drops. We find it by tapping and probing, then repair locally or reline the affected wall depending on how far the wet core has traveled. ## How an insulated box is put together A refrigerated body is a sandwich. There is an outer skin, usually painted aluminum or a smooth FRP, then a foam core that provides the insulation value, then an inner liner that is typically a bonded FRP sheet or an aluminum liner in heavier duty applications. The whole assembly is glued and the bond is what makes it work. The foam is closed cell and it is poured or laid up in place during manufacture. Its insulating performance depends on it staying dry. Water in the core displaces air, and water conducts heat far better than trapped gas, so a wet core is a cold bridge running through the wall. The liner is the only thing keeping the core dry from inside. Every time a pallet corner, a hand truck axle or a load bar end punches or scuffs that liner, the seal is at risk. That is why liner damage on a reefer is not a cosmetic issue the way scuffed interior panels are on a dry freight body. ## What delamination actually is on a reefer wall Delamination is a loss of bond between the liner and the foam core, or between the core and the outer skin. It is not a hole and it is usually not visible. The liner stays where it is because it is fastened at the edges and at the rails, so the failure hides. The mechanism is usually mechanical first, then moisture. An impact breaks the adhesive bond over an area larger than the contact. That creates a void. Condensation forms in the void because it is now a small unventilated cavity in a wall with a large temperature difference across it. The moisture then attacks the surrounding bond, and the loose area grows outward from there. In Southern California the temperature differential is the driver. A reefer body running produce out of the San Gabriel Valley in August has interior temperatures near freezing and exterior skin temperatures well above ambient in direct sun. That gradient across the wall is what pumps moisture into any void that exists. ## Finding a soft area before the whole wall goes The inspection is done from inside, with the box empty and the unit off so the surfaces have equalized. Work systematically along each wall in a grid pattern rather than randomly. - Tap along the liner with a plastic mallet and listen for the note dropping to a dull thud - Press with a flat palm, looking for any give the surrounding wall does not have - Sight along the wall in low light for a bulge or a hollow the eye catches before the hand does - Check every seam and every rivet or fastener line for staining or a dark halo - Look at the floor to wall junction, where water collects and the bond is loaded - Check behind the scuff liner if one is fitted, because damage hides under it - Feel for temperature differences with a bare hand after a cold run, since a wet core reads cold on the inside surface ## Testing whether the core is wet or just debonded A dry debond and a wet core are different repairs, so we establish which one before writing anything. The simplest method is a small probe hole in an unobtrusive spot inside the suspect area, taken to core depth, with the extracted material examined. Dry foam comes out as clean crumbs. Wet foam comes out damp, discoloured and often smells. If the probe brings out water, the core has been compromised long enough for the moisture to travel, and the affected area is always larger than the soft spot you found by tapping. We also weigh the evidence from the outside. A wall with a wet core will often show a frost or condensation pattern on the exterior in the right conditions, because the cold bridge is chilling the outer skin locally. Fleet drivers spot this without knowing what it means: a patch of the outside of the box that sweats when the rest does not. ## Local repair versus relining a wall Small dry delamination gets injected. We drill a pattern of small holes through the liner into the void, inject structural adhesive, and clamp the liner flat against a board while it cures. The holes get sealed afterwards with an approved sealant so the vapour barrier is restored. Damage where the liner itself is punctured or cracked gets a bonded patch or a liner section replacement. The patch overlaps sound liner, is bonded and sealed at every edge, and is finished so the interior stays washable and does not trap product residue. Wet core means relining. There is no way to dry a foam core in place inside a bonded wall. We remove the liner from the affected area, cut back to dry core, replace the wet foam with new insulation board bonded in, then install new liner over the whole section and seal every joint. That is the honest answer even though it is the answer nobody wants to hear. ## The cost of ignoring it, in operating terms A reefer with a wet wall does not fail. It just works harder. The refrigeration unit runs a longer duty cycle to hold setpoint, and the fleet pays for that in fuel every day the unit is loaded. The second cost is product. A cold bridge means the wall surface near it runs warmer than the rest of the box, and cargo stacked against that wall sits in a different temperature than the load sensor is reading. On temperature sensitive freight that becomes a claim. The third cost is spread. A void that could have been injected in a single day grows across a season into a wall that needs relining, and a wall that needs relining becomes a body that needs two walls done. Catching this early is one of the highest return inspections a refrigerated fleet can do. ## Bringing a refrigerated unit to the shop from West Covina This is in shop work. Adhesive bonding on a reefer wall needs controlled temperature and clamping time, and cutting out wet core makes a mess that has to be contained. We do not offer mobile service for any of it. The box needs to arrive empty, washed out and dry inside, and the refrigeration unit needs to have been off long enough for surfaces to come to ambient. A wall that is still cold will condense on itself the moment we open it up, and no adhesive bonds to a wet surface. We work on the body, the liner and the insulation. We do not perform engine or drivetrain work, and we do not service the refrigeration machinery itself. If the unit needs both, coordinate the reefer service first and bring us the body afterwards. Call (949) 799-3387 to book a slot that lines up with your produce or distribution schedule. ## Frequently asked questions ### How can I tell if my reefer liner is delaminated without opening the wall Tap and press. With the box empty and at ambient, tap along the liner with a plastic mallet and listen. Sound bonded wall gives a sharp click. Delaminated wall gives a dull hollow thud. Press with a flat palm and feel for give. Always compare against a known good area of the same wall, because different bodies sound different. Any area that reads soft over more than a hand span is worth having looked at. ### Does a wet core in one wall affect the whole reefer body It affects the refrigeration duty cycle for the whole box, because the unit has to work against the heat gain wherever it is. It does not automatically spread to other walls, since the walls are separate assemblies, but water in a core travels downward and sideways within that panel and will reach the floor to wall junction. From there it can migrate into the floor structure, which is why we probe the floor edge whenever a lower wall reads wet. ### Can a punctured reefer liner just be patched with sealant Sealant closes the surface but does nothing about the void behind it, and it does not restore the bond. It buys time on a small puncture in an otherwise sound wall. It is not a repair on anything larger. What we do instead is bond a proper liner patch over sound material with full edge sealing, so the vapour barrier is continuous and the surface remains washable. Sealant alone tends to fail at the perimeter within a season. ### How long does relining one wall of a refrigerated box take Plan on roughly four to seven working days for a single wall section, longer for a full wall. The variable is cure time on the adhesive, which cannot be rushed, and the amount of wet core that has to be cut back once the liner is off. We often find the wet area is larger than the tap test suggested, so the estimate is written with a supplement expectation. Multi wall jobs are staged rather than done all at once. ### Should the reefer unit be running when I drop the truck off No. Bring it empty, washed and with the refrigeration off long enough that the interior has come up to ambient. A cold wall condenses the moment it is opened, and adhesive will not bond to a wet or cold surface. Twenty four hours off is usually enough in Southern California. If the unit has been running a produce load right up until drop off, expect us to hold it a day before starting work. --- OCRV Center, 23281 La Palma Ave, Yorba Linda, CA 92887. Phone (949) 799-3387. All work is performed in shop at the Yorba Linda facility. We do not run mobile, roadside or fleet route service. Ranges are planning figures, not a quote. Final numbers come from a written estimate on your vehicle.