Walk-In Cooler Panels and Insulation: Damage, Wet Foam and Repair

The panels are the walk-in itself: the walls, ceiling and often the floor. Refrigeration systems get replaced every several years, but panels are meant to last much longer, as long as water stays out of the insulation. Once foam gets wet, it stops insulating, and the problem spreads.

How walk-in panels are built

A walk-in panel is an insulated sandwich: a metal skin on each face (galvanized steel, painted steel, aluminum or stainless) with insulation in between. Panels lock to each other along their edges.

Insulation types

• Foamed-in-place polyurethane. Liquid foam is injected between the skins and expands to fill the panel, bonding to the metal. It is the most common type in modern walk-ins.
• Polystyrene. Rigid boards (expanded or extruded polystyrene) laminated between skins, often with wood or composite framing at the edges.

The two perform differently and age differently. JayComp's article on polystyrene vs polyurethane insulation compares them in detail.

How panels join

• Cam locks. Most panels use cam locks: a hook on one panel edge engages a pin in the next, and turning the cam with a hex wrench pulls the panels tight against each other. The access holes are closed with plugs.
• Tongue and groove edges with gaskets or sealant keep air and moisture out of the joint.
• Seams between wall and ceiling panels and at the floor are sealed, often with a food-safe sealant or trim.

The federal minimums. Walk-ins built on or after 1 Jan 2009 need wall, ceiling and door insulation of at least R-25 for coolers and R-32 for freezers, plus R-28 floors in freezers (10 CFR 431.306). Glazed sections and structural members are exempt.

How panels fail

Water is the common thread. Wet foam insulates poorly, so the inside skin at that spot runs colder and the outside skin sweats. The sweat keeps water around, more moisture migrates in, and in a freezer it can freeze and push the skins apart.

Signs of wet or failed insulation

• Sweating on the outside of the box in one area, not the whole thing. See walk-in cooler sweating outside.
• Frost or ice lines on the outside along a seam or patch.
• Frost and ice inside at a joint, a corner or a ceiling seam. See ice buildup in walk-in freezer.
• Soft, spongy or hollow-sounding spots when you press or tap the skin.
• Stains, rust or mold at seams or along the base. See walk-in cooler smells or mold.
• A panel that bulges or a ceiling that sags.
• A system that runs more than it used to, with no refrigeration fault found.

A technician or panel installer may use an infrared camera to map cold spots from the outside, which shows where insulation is wet or missing without cutting into the panel.

Checks staff can do safely

1. Walk the outside of the box once a month with a flashlight. Look for sweating patches, stains, rust and dents. Check behind shelving and along the base.
2. Check the ceiling from inside and, if you can see it safely, from above. Don't climb on the ceiling of the box; most walk-in ceilings are not designed to be walked on.
3. Look at the seams inside for frost lines, open joints, missing sealant and missing cam lock plugs.
4. Press gently on suspect areas of the outside skin. Soft or crunchy spots are a red flag.
5. Stop water at the source. Don't hose down walls, keep drain lines working (see walk-in cooler leaking water) and report roof leaks on outdoor boxes promptly.
6. Protect the walls. Keep pallets and carts away from panels and use bumpers or rails where traffic is heavy.

Safety: Don't cut or drill into panels to "look inside." Wires for lights, heaters and controls run through panels, and you can create a new path for water.

Repair options

What's possible depends on how much damage there is and whether the panel manufacturer still supports the model.

• Re-tighten and reseal. Loose cam locks can be retightened, missing cam plugs replaced and failed seams resealed with the right sealant. This is often the fix for frost lines at joints.
• Patch skins. Small punctures and tears in the metal skin can be sealed or covered with a patch plate to stop water getting in. It doesn't restore insulation that's already wet.
• Inject foam. In some cases, a small void or crushed area can be refilled with foam. Results vary and it doesn't dry out soaked foam elsewhere in the panel.
• Replace the panel. A single wall or ceiling panel can often be replaced if the manufacturer or a panel supplier can match its size, thickness and locking system. Panels with a door frame, a relief port or a refrigeration penetration are more involved.
• Roof repairs on outdoor boxes: fixing the roof membrane stops ongoing damage but won't dry out wet ceiling panels.

Repair or replace

DOE modeled walk-in panels at an average life of 12 years, with a range from 2 to 25 years. Moisture, abuse and installation quality account for most of that spread. Panel warranties also vary a lot. KPS Global's published limited warranty covers panels for 1 year, not labor and not the refrigeration system; Leer's has been quoted at 10 years. DOE's market survey found panel warranties ranging from 1 to 20 years. Check the actual document for your box and see walk-in cooler warranty claims.

Replacing the box starts to make sense when water has reached many panels, the floor is also failing, you'd be matching an obsolete panel system, or the layout no longer fits the store. Panel condition and refrigeration condition are separate decisions: a new condensing unit doesn't fix wet panels, and new panels don't fix a worn-out compressor. See repair or replace your walk-in and walk-in cooler lifespan.

When the answer is new panels, JayComp designs and installs walk-ins using Leer and KPS/Kysor panel systems, among others.