# Twenty Minutes With A Knuckle And A Meter Twice a year, twenty minutes, a knuckle and a moisture meter, in one fixed order: roof perimeter from a ladder, the penetrations, the slide corners, the floors at each opening, the lower seam. Most of what becomes a five figure repair here was audible or measurable long before it was visible. ## The time budget, and why it is fixed The reason owner inspections do not happen is not lazi, it is that nobody has told anybody how long one takes or what order to do it in. An open ended instruction to check the coach over converts into an afternoon that never gets scheduled. A twenty minute sequence with five stops and a fixed order is a task, and tasks get done. Spring and autumn is the cadence that matters in Southern California, because the wet months and the hot months damage a coach in different ways. Two tools. A knuckle, which is free and covers laminate condition, and a moisture meter, which is the only thing on this list that costs money and is the cheapest diagnostic instrument in the trade. Everything else is a ladder and a torch. The order below is not arbitrary: it runs downhill, because water runs downhill, and every stop is below the previous one on the path water actually takes through a recreational vehicle. ## The roof perimeter, seen from a ladder Do this from a ladder at each corner rather than by walking on the roof. Many roofs will carry a person and some will not, decking condition is exactly what is in question, and a foot through a membrane converts an inspection into a repair. What you are looking for along the roof to sidewall joint is sealant that has shrunk back from one side of the joint, cracked across it, or lifted at a corner. A lifted corner is the finding that matters most, because wind turns a lifted edge into a peeling edge and it does not stop on its own. The membrane surface itself tells you less than owners expect. Chalking is normal ageing. Small punctures matter. What matters most is not visible from a ladder at all, which is whether the decking underneath is dry and solid, and that is the question that decides between a recoat and a replacement. Roof recoat and reseal runs $750 to $4,500 or more, membrane replacement runs $3,500 to $18,000 or more, and recoating over wet decking seals moisture in rather than out. So the ladder inspection is a triage rather than an answer on the roof. Sealant condition, seam and corner condition, and anything obviously punctured. If any of those look wrong, the next step is a proper look at the decking with a meter, and that is a job for a shop with a booth and a ladder rack rather than for somebody balancing on a rung with a torch. ## The penetrations, in the same order every time Every hole through the roof or the wall is a candidate, and the list is short enough to memorise. Vent and fan flanges. The skylight, if there is one. Antenna and satellite mounts. Solar panel feet and the gland where the cable enters. Marker lights. The awning rail and every fastener along it. Window frames, particularly the upper corners. The refrigerator vent. Anywhere something was screwed through a laminate is a hole with a sealant lifespan on it. The check is the same at each: look at the sealant bead, press it with a fingernail, and see whether it has gone hard, shrunk away from the flange, or split. Soft and adhered is fine. Hard and separated is a hole. Take a moisture reading beside any bead that fails that test if the meter reaches, and note it. The point of doing them in a fixed order is that a list done the same way twice becomes a comparison, and comparison is where the information is. ## The four corners of each slide Run the room out and look at the seal from outside, along the top and down each vertical. A wiper seal that has hardened, gone shiny, cracked or taken a set is at the end of its life whether or not anything is wet yet. Then look at how the room sits in its opening: the gap along the top should be consistent from one end to the other, and it frequently is not on a coach that has had a heavy season or a knock. Then run it in and out once and watch it rather than the wall. A room that hesitates, that needs help at one corner, or that stops short of its seal on one side only, is a geometry finding rather than a motor finding. That distinction is worth more than it sounds, because a seal that failed because the room is out of square is a symptom, and replacing the seal without correcting the geometry buys about one season. Slide out mechanism service runs $500 to $8,500 and seal replacement alone runs $400 to $3,000. Tap the wall on each side of the opening while you are there, low down, and compare it with the same height a few feet away. The wall beside a slide opening is where water that got past a seal ends up, and a dead note there is the earliest audible warning available for the most expensive failure sequence on a recreational vehicle. ## The floors at each opening, and the lower seam Inside, stand at each slide sill and at the entry door threshold and shift your weight. Any measurable give at one point that is absent three feet away on the same floor is a substrate finding. Do the same in the bathroom, where the water source is internal and the cause has nothing to do with the roof. Take a meter reading at each of those points and a control reading on the same floor away from any opening, and write all four down with the date. Then go back outside and look along the bottom seam where the sidewall meets the floor, all the way round, on both sides. It is a sealed joint with a service life and it is the joint nobody looks at, partly because it means crouching in a car park. Sealant shrunk away from one side, or a hairline separation running along it, is a joint that is passing water into the floor edge. On a coach kept near the coast it is also working against salt, which shortens everything. ## What to write down, and what triggers a shop visit The whole value of the exercise is in the record, because a single inspection is a snapshot and two inspections are a trend. Keep it on one page per session: date, the meter readings with their positions and the control, sealant condition at each penetration, seal condition at each slide, and any deflection measured at a sill. Photograph anything that looked wrong, wide and close. Then there are five findings that mean booking rather than watching, and the reason to name them is that everything else on this list can reasonably be monitored to the next session. - A membrane lifted or peeling at a corner or along a seam. Wind makes this worse quickly. - Any measurable deflection in a floor, at any of the four locations, however small. - A moisture reading well above its control that has not fallen after a dry fortnight. - A dead note on a sidewall that was not there at the last session. - A slide that hesitates, needs help at one corner, or no longer sits parallel in its opening. ## What twenty minutes does not find It does not find structure. A frame or a body out of published tolerance is invisible to every check on this list, because the panels above it can be perfectly square while the chassis under them is not. That is a measurement job with a reference figure, and no amount of tapping or metering substitutes for it. If the coach has been in an incident, the structural question is separate and it is not answerable in a car park. It also does not find anything inside a wall, which is the honest limit of every non destructive method in this trade. A knuckle locates, a meter quantifies, and neither of them can tell you whether the substrate behind a suspect area is swollen lauan or intact Azdel, or whether the bottom rail of the wall frame has gone. Those answers cost a teardown. What twenty minutes twice a year does is decide when a teardown is worth paying for, which is the only decision an owner is actually in a position to make. ## Related - [/the-center/guides/](https://ocrv.guru/the-center/guides/) - [/services/additional/inspection-evaluation/](https://ocrv.guru/services/additional/inspection-evaluation/) - [/services/roof-slide-awning/roof-repair-replacement/](https://ocrv.guru/services/roof-slide-awning/roof-repair-replacement/) --- Source: https://ocrv.guru/blog/damage-diagnosis/twenty-minutes-with-a-knuckle-and-a-meter/ 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/.