# Damage and Diagnosis Damage diagnosis on a coach starts with one split: is the symptom a load path symptom or a moisture symptom. Those two travel differently through a laminated body, they leave different evidence, and they need different search patterns. Guessing between them is why owners open the wrong wall first. ## Two ways damage travels through a laminated wall A motorhome sidewall is a sandwich: an outer skin bonded to a substrate, over framing, over an inner panel. Two things move through that assembly and they behave nothing alike. A load, from an impact or from a body that has been flexing on a chassis for fifteen years, travels along framing and stops at a joint, so it appears somewhere structurally connected to where it entered and often nowhere near it. Moisture travels by gravity and along a bond line, so it appears below and downstream of where it got in, and it stops nowhere at all until it reaches something absorbent enough to show a stain. Which of the two you are dealing with changes the entire approach. A load path search follows framing and openings: doors, windows, slide cutouts, cap flanges, the places where a wall is interrupted and therefore weakest. A moisture search follows seams and penetrations upward from the wet reading, because water was found where it collected rather than where it entered. Running the wrong search is not merely slow. It ends with a wall opened at the obvious place, nothing found, and a repair order that now includes closing a wall back up. ## Symptoms, and the place each one usually points at These are the pairings that come up most at intake, written symptom first because that is how an owner meets them. None of them is a diagnosis. Each is a starting point that has been right more often than the obvious reading, which is the only useful thing a pattern can offer. - A door or compartment latch that stopped closing cleanly after an impact: an opening that racked out of square, not a hinge. - A long low swell visible only in raking light along a sidewall: a bond line that has released, with or without a mark on the surface. - A soft floor at a slide sill: a wiper or bulb seal, upstream, rather than the floor. - A hollow tap with crisp edges: delamination. A hollow tap with no edge at all: a framing void from the factory. - A star crack in gelcoat with no impact mark on it: load arriving from behind the panel. - A slide that suddenly needs a shove on one corner: the opening moved, and the mechanism is now the victim rather than the cause. - A stain on a ceiling panel: a penetration higher up and usually to one side, never the spot itself. ## What cannot wait and what can wait a season Urgency sorts on two questions: is anything still moving, and is anything still wet. A structure that racked is not going to unrack, but a mechanism operated against it keeps destroying itself, so a slide or a door that binds becomes urgent the day it starts binding. Water is urgent regardless of the calendar, because the cost curve is a step rather than a slope. Wet decking or a wet subfloor turns a sealant job into water damage restoration at $750 to $15,000, and the crossing point is measured in weeks of marine layer rather than in years. Gelcoat oxidation, crazing and cracked decals are genuinely fine to leave until it suits you. ## The limits of what looking can settle The unflattering part is that looking has limits, including ours. An estimate written from photographs is a guess about a closed vehicle, and it is a guess whether a carrier writes it or a shop does. That is why an RV systems estimate here is $150 and an in depth diagnostic is one hour at $285, each credited against an authorised repair. The honest version of finding out involves a meter, a ladder and panels coming off, and those cost time. An owner who understands that stops asking for a figure over the phone and starts asking what the range depends on, which is a question with a real answer. One input costs nothing and outperforms most of the equipment in this building. What you heard and felt. A hollow bang followed by a new rattle over bumps names a bracket or a fastener that let go somewhere nobody has looked yet. A change in how a door sounds when it closes is a structural report delivered as an annoyance. Those sentences decide where teardown starts, and starting in the right place is worth more than a day of searching. ## Related - [The Tap Test Finds What The Eye Misses](https://ocrv.guru/blog/damage-diagnosis/the-tap-test-finds-what-the-eye-misses/) - [Two Moisture Readings And A Dry Control](https://ocrv.guru/blog/damage-diagnosis/two-moisture-readings-and-a-dry-control/) - [A Quarter Inch Of Flex Means Wet Lauan](https://ocrv.guru/blog/damage-diagnosis/a-quarter-inch-of-flex-means-wet-lauan/) - [Damage Stops Where The Adhesive Still Holds](https://ocrv.guru/blog/damage-diagnosis/damage-stops-where-the-adhesive-still-holds/) - [Straight Panels Can Sit On A Bent Frame](https://ocrv.guru/blog/damage-diagnosis/straight-panels-can-sit-on-a-bent-frame/) - [Twenty Minutes With A Knuckle And A Meter](https://ocrv.guru/blog/damage-diagnosis/twenty-minutes-with-a-knuckle-and-a-meter/) --- Source: https://ocrv.guru/blog/damage-diagnosis/ OCRV Center, 23281 La Palma Ave, Yorba Linda, CA 92887. (949) 799-3387. Serving Laguna Niguel, California. All work performed in shop. No mobile or roadside service. Licences: California Bureau of Automotive Repair ARD00288521; EPA CAL000367879. Published ranges are ranges, not quotes. Every figure traces to https://ocrv.guru/prices/.