RV Delamination: What Sidewall Bubbles Mean and How Repairs Work

Most modern RV sidewalls are built like a sandwich. A thin fibreglass outer skin is glued to a lightweight backing layer, which is bonded to a core of foam or wood framing, with the interior wall panel on the other side. The whole assembly gets its strength from those glue bonds. When the layers stay bonded, the wall is light and surprisingly stiff.

Delamination is what happens when those glue bonds let go. The fibreglass skin separates from the layer behind it, and because it is no longer held flat, it bulges outward. That is the bubble or wave you see when light hits the wall at an angle. Press on it and it may flex, creak, or feel spongy compared to the solid wall around it.

The adhesives in a sidewall are strong, but they do not tolerate constant moisture. Water gets in through a failed sealant joint, a cracked corner moulding, a window frame, a marker light, or a roof seam, then travels down inside the wall. Once the backing layer gets wet it swells, softens, and releases its grip on the fibreglass. The bubble you see on the outside is often the last stage of a leak that started somewhere higher up.

Alberta weather makes this worse. Trapped moisture freezes and expands in winter, prying the layers apart a little more each cycle. Strong sun on a dark sidewall then heats the trapped moisture, which pushes on the weakened bond. A small soft spot in fall can be a much larger bubble by spring, which is why delamination should never be treated as a wait and see problem.

It is also worth knowing that delamination is a symptom, not the disease. The disease is the leak. Fixing the bubble without finding and sealing the water entry point means the problem comes back.

The first step in any honest delamination repair is diagnosis. A technician traces where the water is coming from, checks how far the separation extends beyond the visible bubble, and confirms whether the wood framing or floor behind the wall is still sound. Moisture readings and pressing along the wall reveal a lot, because the damaged area is usually larger than what you can see.

If the separation is caught early and the core is still dry and solid, the skin can sometimes be re-bonded. This typically involves injecting adhesive between the layers and clamping or bracing the wall flat while it cures. Done properly, this restores the bond and stops the bubble from spreading, and it is far less invasive than opening the wall.

When water has been in the wall long enough to rot the backing or framing, injection alone will not hold. At that point the repair becomes structural. The affected section of wall is opened, the rotten material is cut out and replaced, insulation is renewed, and the skin is re-bonded or replaced. It is a bigger job, but it is the only repair that actually lasts once rot is involved. Either way, the leak that started it all gets sealed as part of the work.

First, stop water from getting in. Check the caulking and seals above and around the bubble, and keep the RV covered or under a roof if you can. Avoid pressing repeatedly on the bubble, since flexing can spread the separation.

Then get it assessed sooner rather than later. Delamination is one of the few RV problems that genuinely gets more expensive the longer it sits, because dry separation can be re-bonded while wet, rotten walls need rebuilding. If you are in the Calgary area, bring it to Horton RV Services. We will trace the leak, tell you honestly whether your wall can be re-bonded or needs structural repair, and fix the source so you are not back next season with a bigger bubble.