Delamination Repair in San Juan Capistrano

Pull an RV sidewall apart and you find five or six layers that were pressed together as one piece. Outermost is the skin, either a smooth fiberglass sheet or a textured Filon panel. Behind it sits a substrate board, historically luan plywood and on newer units frequently Azdel, which is a polypropylene and fiberglass composite. Behind that is the insulation, usually block foam cut to fit between the framing. The framing itself is an aluminum tube cage, and an interior decorative panel closes the assembly on the inside face.

That whole stack was assembled with adhesive and pressed in a heated hydraulic press or under vacuum, cured flat, then cut to length and fitted with windows and doors. The wall gets its stiffness from the sandwich acting as a unit, exactly like an aircraft floor panel. The skin carries tension, the studs carry compression, and the bond between them transfers shear. Break the bond and each layer is suddenly working alone, which none of them were designed to do.

This is why delamination is a structural finding and not a cosmetic one. A wall with two square metres of dead bond has lost stiffness in that area, which lets it flex further, which peels more bond at the edges of the failure. Delamination grows. It does not sit still and wait for you to get around to it, and the growth accelerates once the skin can move enough to work the adhesive at the boundary.

Azdel changed the arithmetic on newer coaches, and mostly for the better. It does not absorb water, does not rot and does not lose structure when wet, so a leak into an Azdel wall produces a very different outcome from the same leak into luan. What Azdel does not do is prevent bond failure. It resists the consequences of moisture rather than the moisture itself.

Water is the headline cause and the entry point is almost never where the bubble appears. Water gets in at a window frame whose butyl has hardened and shrunk, at a marker light screwed through the skin without sealant behind the flange, at an awning arm bracket, or along the roof-to-wall seam where the lap sealant cracked. It then runs down inside the wall along the path gravity offers, soaking the substrate somewhere entirely different from where it entered. Owners chase the bubble and never find the leak.

Thermal cycling does the rest. A coach parked on asphalt in Orange County sees a dark sidewall reach well past 140 degrees on a summer afternoon and drop forty degrees within an hour of the marine layer arriving. Skin and substrate have different coefficients of thermal expansion, so every one of those cycles works the adhesive in shear. It is a fatigue process, and it explains why delamination shows up on the sun-facing side of coaches far more often than on the shaded side.

Manufacturing variance accounts for a real share of it too. Press temperature, adhesive open time, spread rate and clamp pressure all have to be right, and a panel that came out of the press slightly under-bonded will look identical to a good one for the first five years. Certain model years from certain builders are notorious in the trade for exactly this reason, and a coach that delaminates in three unrelated places on the same wall usually has a build problem rather than a leak.

Finally there is mechanical insult: a peel-mode side swipe, a ladder loaded past its rating, a bike rack cantilevered off the rear wall, or a slide room that has been binding and levering against its opening. Any of these can break bond locally, and the local failure then propagates through the thermal cycling described above. Owners often remember the event, which makes these the easiest cases to date and the easiest to submit to a carrier with a credible causal chain attached.

The tap test is the primary tool and it costs nothing. A bonded panel returns a tight, high, solid note. A delaminated area returns a lower, hollow, drum-like sound. Working outward from the visible defect in a grid, the boundary between the two sounds is unmistakable once your ear is calibrated, and it is nearly always significantly larger than the visible bubble. We mark that boundary in tape on the vehicle and photograph it, because it defines the repair area and it defines the price.

The moisture meter answers the question the tap test cannot: is the substrate wet, and is it still wet. Pin readings taken through the interior panel or at the edges give a moisture content percentage. Sound dry luan sits in the single digits. Anything above roughly sixteen percent is actively wet and anything above twenty five has almost certainly begun to rot. Readings are taken at the failure and at control points on undamaged wall, because absolute numbers mean little without a baseline for that coach.

A long straightedge held against the wall shows the geometry of the failure. A gentle dish means the skin has relaxed away from the substrate over a broad area. A sharp ridge means the substrate itself has swelled or separated at a seam. Combine that with the low-sun shadow read, standing at one end of the coach early or late in the day and sighting down the wall, and the entire failure map becomes visible in a way that no amount of standing directly in front of the panel will reveal.

Last comes the leak hunt, and it is the step most often skipped. Repairing delamination without finding the water source is repairing a symptom. We pressure or water test the suspect penetrations, pull a window frame if the evidence points there, and inspect the roof seam above the failure. The written scope names the leak source, and if we cannot find it we say so rather than implying the problem is solved.

Where the substrate is dry and structurally sound and the failure is isolated, resin injection is the right repair. Small ports are drilled through the skin into the void, a low viscosity epoxy is introduced, and the panel is drawn flat and held with cauls, a clamping frame or a vacuum bag while it cures. Done properly it restores the shear transfer that was lost and the finished wall is flat, sound and quiet under the tap test.

Done improperly it is the most common failed repair in the industry. The failure modes are consistent: resin injected without adequate clamping cures with the skin still bowed, so the wall is now permanently bubbled and permanently bonded that way. Resin injected into a wet cavity cannot bond to saturated wood and gives you a stiff patch surrounded by a growing failure. Too few ports leave uninjected voids between them. Too much pressure blows the skin outward and enlarges the delamination in the act of repairing it.

The limits are worth stating plainly. Injection does not work on rotten luan, because there is nothing left to bond to. It does not work where the foam insulation has crushed or separated, because the void is too large and too irregular to fill. And it does not fix a wall that has been wet for three seasons, no matter how many holes you drill. When we look at a coach and say injection is not the answer, that is why.

When the substrate has failed, the repair is surgery. The exterior skin is cut at a planned boundary, ideally at a graphic line, a body seam or a panel joint so the eventual finish has a place to hide. Windows, lights, awning brackets and anything else penetrating the repair area come off. The skin is peeled back or removed entirely, and the ruined luan, degraded foam and any corroded aluminum framing behind it are removed down to sound material.

Rebuild goes back in the reverse order with better material than left the factory. Azdel or marine-grade substrate replaces luan wherever the original construction allows it, since it will not repeat the failure. Foam is cut to fit the bays properly rather than stuffed. Aluminum framing that corroded, usually where a steel fastener sat against it and set up a galvanic cell, gets replaced and isolated. Adhesive goes on at the specified spread rate, and the assembly is clamped or vacuum bagged flat for the full cure.

The finish work is what owners actually see and it is not trivial. A re-laminated section has to fair into the surrounding wall within a tolerance the eye cannot detect in raking light, which means long-board blocking and patience. Then the panel is refinished and the graphics are reproduced or re-run. On a coach with complex multi-colour swoops, that reproduction can be as much work as the lamination.

A rebuild of this scale sits at the upper end of the published band, and it is a real conversation about value. On a well-maintained diesel pusher with an otherwise sound interior it is straightforward economics. On a fifteen year old trailer with a soft floor and a marginal roof it may not be, and we will tell you that before you spend money finding out.

By the time a wall has delaminated from a leak, water has usually been in the structure for a season or more, and it did not stop at the wall. The classic path runs from a window or roof seam, down the interior of the sidewall, into the floor at the wall-to-floor joint, and then laterally through the subfloor. Owners find the bubble on the outside and are surprised when the estimate includes floor work.

We check the floor at the base of any delaminated wall as a matter of course: probing for softness, reading moisture at the perimeter, and pulling a section of interior trim where the evidence suggests it. We also look at the wiring and any appliance vent passing through the wet zone, because chronic damp in an aluminum-framed wall around copper and steel produces corrosion that shows up later as an intermittent electrical fault nobody can trace.

Mould and odour deserve a direct answer. A wall that has been wet long enough to rot luan very often smells, and the smell lives in the substrate and the insulation, not on the surface. Removing the material removes the odour. Sealing over it does not, and any repair that leaves saturated foam in the cavity will still smell in July no matter how good the exterior looks.

This is the hardest conversation in the shop. Most recreational vehicle policies exclude damage from gradual water intrusion, wear, deterioration and manufacturing defect, and delamination that developed over three seasons from a hardened window seal falls squarely into all four categories. Owners frequently arrive expecting coverage and leave with the news that this is theirs to pay for, and we would rather deliver that news at the estimate than after a teardown invoice has been run up.

There are real exceptions. Delamination caused by a covered event is a different claim entirely: a side swipe that peeled bond in the impact zone, a hail event that fractured the skin and let water in, a tree limb through the roof, or a slide that failed and levered against its opening. In those cases the delamination is consequential damage from an insured loss, and the way to get it paid is to establish the causal chain in writing with photographs from the day of the event forward.

Manufacturer coverage is worth checking on newer units through your selling dealer, and some builders have historically extended goodwill on known lamination issues. That path runs through the manufacturer rather than through us. What OCRV Center can supply either way is the documentation: tap test boundary photographs, moisture readings with control points, the identified entry path and a written scope. Whoever ends up paying, that file makes the case.

Delamination is cheap to fix small and expensive to fix large, and the gap between those two states is measured in seasons rather than years. A coach stored outdoors near the coast, taking marine layer moisture at night and full sun by eleven, moves through that gap faster than one kept inland under cover. If you store in San Juan Capistrano and you have noticed anything on the sidewall, the useful move is to have it looked at now rather than after the summer.

Owners drive up the 241 or Interstate 5 and drop the vehicle with us in Yorba Linda, roughly 26 miles north and about forty minutes clear of commute traffic. A diagnostic visit is a couple of hours: tap test, moisture readings, straightedge, shadow read and a leak hunt, with a written scope and photographs at the end. You leave knowing the size of the problem and the size of the number, which is more than most owners have.

Call (949) 799-3387 before you make the drive if the wall is visibly bubbled or the interior smells damp, because we may want to schedule the diagnostic differently. Do the sighting exercise yourself first: stand at the front corner early in the morning, sight down the sidewall with the sun low, and take a photograph. That single image tells us more than a dozen close-ups.