Reference

The Vocabulary an Estimate Uses, Defined in Plain Language

A working glossary of 180 terms that appear on RV and commercial vehicle repair estimates, insurance scopes and parts invoices. Each definition is written the way we would explain it across the counter at OCRV Center, not the way a manufacturer service bulletin would.

Why a glossary is the most useful page on a repair shop website

The single most expensive thing that happens to an owner during a repair is not a high labor rate. It is agreeing to a scope they did not understand. An adjuster writes "R and I fiberglass sidewall, blend adjacent panel," the owner nods, and three weeks later there is an argument about whether the blend was supposed to include the cap. Nobody in that exchange behaved badly. One party knew the vocabulary and one did not.

Every term below is defined at the level a person needs to read their own paperwork and ask a useful follow up question. Where a term has a specific meaning in the RV trade that differs from its meaning in automotive work, the definition says so, because that gap is where most misunderstandings live. A Hacienda Heights owner reading an estimate for a Class A coach is reading a document written in two overlapping dialects at once.

How the terms are grouped

The list is alphabetical rather than categorical, because an owner arrives here with one unfamiliar word from one document, not with a desire to study a subject. Use the browser find command. If the term you are looking for is missing, it is worth telling us, because a term we failed to define is a term we are probably also failing to explain at the counter.

Terms that map to work we perform link to the page for that work, so a definition can become a price band and an hour range in one click. That is deliberate. Knowing what a Schwintek rail is matters less than knowing that a Schwintek rail replacement runs a specific number of hours and a specific parts lead time.

180 terms

A to Z

Delamination: The glue line between an outer fiberglass skin and the substrate behind it lets go, so the wall reads solid but flexes under a palm. Sight down the side in low raking light and the bubble or flat spot shows up long before a moisture reading does.
Luan: The thin tropical plywood laid behind a fiberglass skin on most stick and tin or laminated walls. It bonds well and weighs little, but it drinks water at any open seam and goes to pulp, which is why a small roof leak turns into a sidewall job.
Lauan Substrate: Alternate spelling used on parts invoices for the same thin plywood backer. When we quote a sidewall, the substrate line matters more than the skin line, because replacing pulped backer means peeling the wall open rather than filling from outside.
Filon: Rolled fiberglass reinforced sheet used as exterior skin on many trailers and fifth wheels. It arrives in a roll, so it carries a memory and a gloss direction. We orient replacement sheet the same way the factory did or the finish reads mismatched in sunlight.
Gelcoat: The pigmented resin surface layer sprayed into a mold face, so on a fiberglass cap the color is part of the laminate rather than a coating on top. Repairs get gelcoat paste, then wet sanding and buffing, not primer and base.
Vacuum Bag Injection: Repair method where we drill a grid of small ports into a delaminated area, pull the panel flat under vacuum, and inject structural adhesive through the ports. It restores bond without cutting the skin off, which keeps the original gloss intact.
Panel Adhesive: Two part structural adhesive that carries load across a bonded joint instead of clamping it like a fastener. Open time, mix ratio and clamp pressure all matter. A rushed spread is the usual reason a repaired sidewall lets go a second time.
Azdel: Composite backer panel of polypropylene and fiberglass used instead of plywood on some laminated walls. It will not rot and it does not wick, so a leak stays local. It also sands and bonds differently, so patch prep changes when we find it.
Block Foam Core: The rigid foam sandwiched inside a laminated wall between skin and backer. It gives the panel stiffness and insulation value. Once water tracks through it the foam crushes, and a crushed core is why a wall looks wavy even after the skin is rebonded.
Sidewall Stack: The full layer order of a laminated wall, typically skin, adhesive, foam, framing, backer and interior finish. We write the stack on the estimate because the number of layers disturbed drives labor far more than the size of the visible damage.
Print Through: Framing members or seam tape telegraphing through the outer skin as faint ridges. It shows the adhesive shrank or the panel was pressed unevenly. Cosmetic at first, but print through usually marks where the bond is thinnest and will fail next.
Tenting: A raised ridge running along a bond line or seam where the skin has lifted into a peak. Push it down and it springs back. Tenting means trapped air or a failed adhesive bead, and it traps water at the high edge every time it rains.
Void Mapping: Tapping and probing a suspect panel, then marking every hollow with tape so the true boundary of the failure is on the wall in front of the owner. Mapping is what turns a guess about sidewall damage into a repair plan with a defensible labor number.
Soft Spot: An area of floor, wall or roof that deflects under hand or foot pressure. Softness is a symptom of wet or crushed structure underneath, not a surface issue, so filling it from outside buys weeks and costs the owner the teardown twice.
Scarf Joint: A long tapered overlap cut into old and new laminate so the splice carries load across a wide glue area instead of a butt line. Done right the joint disappears under finish. Done short it becomes a visible crack within a season of flexing.
Sidewall Reskin: Removing the exterior skin over a defined area and replacing it, usually because the backer or core behind it is unsalvageable. Reskin work drives trim, window, awning rail and light removal, so the parts list is long even when the panel itself is cheap.
Resin Injection Repair: Filling a hollow laminate area with flowable resin or adhesive through drilled ports rather than opening the wall. Best on tight local voids with dry structure. If moisture readings are high, injection only seals the water in and hides the rot.
Substrate Rot: Wood behind the skin that has gone soft, black or crumbly from long term wetting. It has no fastener holding power left, so screws for awning rails and hardware spin. Rot dictates how far past the stain line the repair boundary has to move.
Bond Line: The thin adhesive layer that actually holds a laminated panel together. Almost every sidewall failure we open is a bond line failure, not a material failure, which is why surface prep and clamp time get more attention here than the patch itself.
Peel Strength: How much force it takes to lift a bonded skin away from its substrate at an edge. Low peel strength shows as skin that comes off in sheets during teardown. We test small tabs during removal to decide how wide the sound bonding zone really is.
Lamination Press: Clamping and weighting a rebonded panel flat while adhesive cures, using battens, straps or vacuum rather than a single point clamp. Pressure has to be even across the whole area, because a panel cured with a dip in it keeps that dip permanently.
Sidewall Stud: The aluminum or wood vertical framing member inside a wall. Fasteners and cabinet loads land here, so locating studs before drilling matters. A bent stud from an impact will hold a wall out of plane even after the skin is replaced and painted.
Skin Seam Batten: The trim strip over a vertical joint between two skin sheets, bedded on putty tape and screwed down. Battens are the most common entry point for water on older units, because the putty behind them hardens and shrinks away from the fastener heads.
Moisture Meter Survey: Gridded readings taken across walls, floor and roof so wet structure is documented as numbers and locations, not opinions. The survey is the backbone of an insurance supplement, since it shows an adjuster where damage extends past what the photos caught.
EPDM Roof Membrane: Black synthetic rubber sheet, usually with a white top layer, glued over the roof decking. It sheds a chalky residue as it ages and streaks the sidewalls. Patchable in place, but once it gets brittle at the seams a full membrane replacement is the honest call.
TPO Roof Membrane: Thermoplastic single ply roofing that can be heat welded rather than only glued. It stays cleaner than rubber and does not chalk much. Repairs need the right tape and primer, because sealants formulated for rubber do not stick to it reliably.
PVC Roof Membrane: Vinyl based single ply membrane found on higher end coaches. It welds cleanly and holds gloss, but plasticizer loss makes old sheet shrink and stiffen. Material identification comes first, since PVC, TPO and rubber each take a different adhesive family.
One Piece Fiberglass Roof: A molded fiberglass roof panel with no field seams across it. Far fewer leak paths than sheet goods, and it can be sanded, filled and painted like any body panel. Damage repair looks more like collision work and less like roofing work.
Aluminum Roof: Rolled aluminum sheet roofing, common on vintage trailers and some cargo builds. It dents instead of tearing and it works with the frame, so fastener seams loosen over time. Coating and seam treatment matter more here than membrane adhesive does.
Lap Sealant: Flexible sealant run over the top of a horizontal seam or fastener head to shed water. It is the maintenance layer, not the seal itself. Owners who top coat over cracked old sealant trap the failure underneath and keep the leak running.
Self Leveling Sealant: Sealant formulated to flow out flat on a horizontal surface so it wets into a seam without tooling. Used on roof penetrations and flanges. Applied on a vertical surface it simply runs down the wall and leaves the joint open.
Non Sag Sealant: The vertical counterpart to a self leveling product. It stays where the gun puts it on a wall or a cap seam without slumping. Using the two products in each others place is one of the most common reasons a resealed unit still leaks.
Butyl Tape: Non curing putty rope used as the bedding layer under any roof or wall flange. It stays pliable and squeezes out under fastener torque to fill the gap. Butyl does the sealing, and the sealant on top only protects it from sun and abrasion.
Eternabond: Heavy butyl backed seam tape used to bridge a membrane tear or a seam permanently. It bonds hard and does not come back off cleanly, so we place it deliberately. Taped over dirt or chalk it lifts at the edges and channels water sideways.
Dicor: Common brand of roofing membrane and sealants written on many parts lines. Naming the brand on an estimate matters because its rubber, its adhesive and its sealants are a matched system, and mixing families across a repair is what causes early seam release.
Roof Rafter: The lateral structural member spanning the coach width above the ceiling. Rafters set roof shape and carry walking load. A cracked rafter from a tree strike shows as a dip that returns no matter how many times the membrane above it gets patched.
Roof Decking: The sheet layer, plywood or composite, laid over the rafters and under the membrane. Decking is what a foot actually stands on. Once water has reached it, membrane work alone is cosmetic and the soft area keeps spreading outward from the original leak.
Roof Penetration: Any hole cut through the roof for a vent, antenna, air conditioner, refrigerator stack or wiring. Every penetration is a maintained joint with a service interval. Most roof leaks we trace start at a penetration, not in the open field of the membrane.
Vent Flange: The flat perimeter of a roof vent or fan that gets bedded on putty and screwed to the decking. Overtightened screws dish the flange and break the butyl seal. Cracked plastic flanges are cheap parts that cause expensive decking replacement when ignored.
AC Shroud: The plastic cover over a rooftop air conditioner. It is a wind and sun part, not a sealing part, but a shattered shroud lets debris and water into the condenser. Replacement shrouds yellow at a different rate than the original, which owners notice.
Roof Ladder Mount: The bracket set that anchors a rear ladder through the wall or cap into structure. Mounts carry a person and a load, so backing plates matter. A ladder pulling loose usually means the backer behind it is wet, which turns a bracket job into a cap job.
Roof Camber: The designed rise from the sidewall edge to the centerline of the roof. Camber is what pushes water to the drip rails. Lose it through crushed structure and the roof holds standing water over the exact spot that is already failing.
Crowned Roof: A roof built with deliberate crown so it drains both directions. On a crowned unit we set new rafters and decking to the original profile with a batten and string, because a flat rework looks correct in the bay and puddles in the driveway.
Termination Bar: Metal strip screwed over a membrane edge to mechanically hold it and take stress off the adhesive. Used at cap transitions and around large penetrations. The bar needs sealant at its top edge or it becomes a shelf that funnels water under the sheet.
Roof Membrane Shrinkage: Older single ply sheet contracting over years of heat cycling, pulling itself away from corners and flanges. You see it as tight wrinkles near the caps and sealant beads stretched thin. Shrunken sheet cannot be stretched back and needs replacement.
Chalking: The powdery white film a weathering rubber roof gives off, which then streaks down the sidewalls in rain. Chalk also kills adhesion, so any tape or sealant applied over an unscrubbed chalked surface is sitting on dust rather than on the roof.
Ponding: Standing water sitting on a roof after rain instead of draining off the edges. Ponding points to lost camber, a sagged rafter or a crushed section. The puddle marks the low spot precisely, which makes it a useful diagnostic before any teardown starts.
Skylight Dome: The clear or smoked acrylic bubble over a bath or hallway opening. Sun makes it brittle, then a low branch or hail cracks it. Domes are inexpensive parts, but a cracked one over a shower soaks the ceiling panel and the cabinet below within one storm.
Front Cap Seam: The joint where the molded front cap meets the roof and sidewalls. It flexes constantly at highway speed and is a top three leak source on motorhomes. We inspect it with the sealant cut back, because surface cracks hide a much wider open joint.
Rear Cap Seam: The same critical joint at the back of the coach, usually complicated by ladder mounts, camera housings and running lights. Water entering here tracks forward under the membrane, so the stain on the ceiling can appear several feet from the actual opening.
Schwintek In Wall Slide: Slide system with vertical motor and gear tracks mounted inside the side walls of the room itself. Compact and common on lighter trailers. It depends on both sides staying timed together, so a dragging seal or a low battery shows up as a crooked room.
Lippert Through Frame Hydraulic Slide: Heavy room mechanism driven by hydraulic cylinders mounted through the chassis frame, used on large fifth wheel and motorhome rooms. Strong and quiet when maintained. Failures usually trace to fluid level, a leaking cylinder seal or a bent rail rather than the pump.
Lippert Electric Rack And Pinion Slide: Electric motor turning a pinion gear along a toothed rack under the slide floor to push the room in and out. Simple and serviceable. Bent rack teeth from forcing a frozen room are the damage we most often find during teardown on these.
Power Gear Cable Slide: Cable driven room system where steel cables pull the slide in and out through pulleys at each corner. Cable tension is the whole ballgame. Loose cables let the room hang low and cock in the opening, which tears seals and cracks the fascia trim.
BAL Accu Slide: Cable and drum slide system found on many towable floorplans, recognizable by its underfloor drive assembly. It needs the cables adjusted as a matched pair. Adjusting one side to chase a gap is why so many of these come in fighting themselves.
HWH Hydraulic Slide: Hydraulic room and leveling system used on higher end coaches, with its own pump, valve block and control panel. Diagnosis starts at the valve solenoids and fluid condition. Because it shares a pump with the jacks, one weak circuit can affect both systems.
Slide Topper: The fabric awning stretched over the top of an extended slide room to keep debris and water off the roof of the room. When the fabric tears or the spring tension dies, water pools on the slide roof and finds the seam at the header.
Wiper Seal: The stiff blade seal that sweeps the top and sides of the slide room as it travels, scraping grit off before it reaches the interior. A curled or missing wiper is why an owner finds pine needles and water on the floor after every trip.
Bulb Seal: Hollow rubber seal that compresses when the room is closed to make the weather seal against the sidewall. Once it takes a permanent set it stops springing back, and the room will read closed at the switch while daylight shows at the corner.
D Seal: Seal with a D shaped cross section used along slide flanges and floor edges where a bulb would be too tall. It sets and flattens with age. Mixing seal profiles during a repair leaves a step at the transition that leaks and whistles at speed.
Slide Flange: The perimeter frame around the wall opening that the room seals against. If an impact tweaks the flange, no amount of new rubber will seal the room. We measure the opening diagonals before ordering seals so the sequence of repair is correct.
Out Of Sync Slide: One side of a room traveling farther than the other, leaving the slide crooked in its opening. Causes range from a dry seal to a failed motor encoder. Running a crooked room repeatedly bends rails and shears gear teeth, which turns cheap into expensive.
Controller Learn Mode: The procedure that teaches a slide controller the stop positions and motor counts for a given room. After motor, controller or gear pack work, the room must relearn its travel or it will keep stalling short and reporting faults that look like a wiring problem.
Slide Sync Bar: Mechanical link tying the two drive sides of a room together so they cannot travel independently. When a sync bar is bent or a mount is loose the room walks out of square. Straightening the bar comes before touching any electronic adjustment.
Slide Rail Gear Pack: The gearbox and drive assembly bolted to a slide rail. Gear packs are wear items and they are the noisy part when a room groans. Replacing one without inspecting the rail it drives is how the same failure returns within a season of use.
Slide Out Motor Encoder: The counting device inside or behind a slide motor that reports shaft revolutions to the controller. Bad counts mean the controller thinks the room is somewhere it is not. Symptoms mimic a mechanical bind, so we verify counts before condemning hardware.
Slide Room Header: The structural beam above the slide opening carrying roof load across the gap. A sagging header pinches the top of the room and grinds the wiper seal. Any collision to the upper corner of a slide opening gets a header check before seal work.
Hydraulic Slide Cylinder: The ram that pushes and pulls a hydraulic room. Seals weep before they fail outright, so a faint oil film on the rod is an early warning. Fluid on a slide floor also destroys carpet and vinyl, which adds interior work to a mechanical repair.
Slide Manual Override: The mechanical means of moving a dead room, usually a crank socket or a release valve. Knowing the override location matters because forcing a stuck room with the switch is what bends rails. We show owners the override point when the unit is picked up.
Slide Room Sag: A room that droops at the outboard corners when fully extended, from worn rollers, cable stretch or a tired floor. Sag shows as a diagonal gap at the top seal. Measuring the drop with the room out tells us whether rollers or structure is the culprit.
Slide Out Cable Tension: The preload on the pull and push cables of a cable driven room, set to a spec at each corner. Uneven tension is the single most common reason these rooms leak. Setting it takes patience and a test cycle, not a single pass with a wrench.
LP Regulator: The device that drops tank pressure to the low, steady pressure appliances expect. Regulators age and drift, and a drifting regulator shows up as yellow flames, a lazy furnace or a refrigerator that will not hold temperature on gas.
Two Stage Regulator: The standard configuration on a coach, dropping pressure once at high stage and again to delivery pressure. Two stages hold delivery steady as tank pressure swings with temperature. Single stage substitutes cause appliance complaints that look like appliance failures.
POL Fitting: Left hand threaded male fitting that seats inside a cylinder valve on older removable bottles. It seals metal to metal, no tape, no dope. A POL joint that needs sealant is a damaged seat and gets the part replaced rather than dressed up.
ACME Fitting: The large external threaded connection on modern bottle valves that hand tightens without a wrench and includes a flow limiting feature. Cross threading it damages the valve. We check the o ring seat any time a bottle connection has been leaking at the hand wheel.
Manometer: The water column or digital gauge used to read the low pressure side of an LP system in inches of water. Nothing about gas system health is guesswork with one connected. Delivery pressure and leak testing both get documented from this reading.
Timed Pressure Drop Test: Charging the LP system to test pressure, closing it off, and watching for any drop over a set interval. It either holds or it does not. This test is what separates an actual leak from a smell complaint caused by a lazy burner or a stale regulator vent.
DSI Ignition: Direct spark ignition, where a control board sparks the burner and proves flame electronically instead of using a standing pilot. Most furnace and water heater no heat calls on these come down to a dirty electrode, weak ground or wrong gap, not the board.
Thermocouple: The sensor in a standing pilot appliance that generates a small voltage from flame heat to hold the gas valve open. When it weakens, the pilot lights and dies seconds after the knob is released, which owners almost always read as a bad gas valve.
Sail Switch: A vane in the furnace airstream that proves the blower is actually moving air before gas is allowed to flow. Dirty ducting or a sticky vane means the furnace runs the blower and never lights, a symptom that sends people shopping for a new furnace.
Transfer Switch: The device that decides whether the coach runs on shore power or generator power and prevents both from feeding the panel at once. Burned contacts here cause intermittent power loss on one leg, which reads to an owner as a failing air conditioner.
Converter: The unit that turns incoming shore power into twelve volt output to run lights, pumps and control boards while also charging the battery bank. A tired converter shows up as dim lights and short battery life, often blamed on the batteries first.
Inverter: Hardware that converts battery voltage into household style alternating current so outlets and electronics work without shore power. Sizing matters, and so does what circuits it feeds. Most complaints we chase are wiring and load related, not inverter defects.
Inverter Charger: A combined unit that inverts from the battery bank when off power and charges the bank when connected. Programming has to match the battery chemistry installed. A lead acid charge profile on a lithium bank is a common and costly configuration error.
MPPT Charge Controller: Solar controller that tracks the panel array's best operating point and converts excess voltage into usable charging current. It earns its cost on cold, bright days and with higher voltage arrays. Correct wire gauge and fusing decide whether that gain is real.
PWM Charge Controller: Simpler solar controller that pulses the panel connection to regulate charging, giving up some harvest for lower cost. Fine on small arrays matched to the bank voltage. Pairing one with a high voltage array wastes most of the panel capacity an owner paid for.
Shore Power: Utility power fed into the coach through the main cord at a campground pedestal or a home outlet. Everything downstream depends on the pedestal being wired correctly, which is why we test the source before we start diagnosing the coach's own panel.
Thirty Amp Service: A single hot leg service on a three prong cord, common on trailers and smaller motorhomes. It gives one air conditioner and modest loads. Owners who add a second roof unit on this service trip breakers all summer and blame the appliance rather than the supply.
Fifty Amp Service: A two hot leg service on a four prong cord that splits loads across both legs. It supports multiple air conditioners and a residential refrigerator. When one leg drops, half the coach goes quiet, which is the classic symptom of a failing cord end or transfer switch.
Reverse Polarity: Hot and neutral swapped somewhere upstream, usually at a pedestal or an adapter. Appliances still run, so nothing seems wrong, but switches interrupt the neutral instead of the hot and anything touched during service is live. Testing the source takes seconds and prevents that.
Ground Fault: Current escaping its intended path and returning through ground, often through moisture in a water heater element, a pump or damaged wiring. A tripping pedestal breaker that resets fine with the cord unplugged points straight at the coach rather than the campground.
Chassis Bonding: The deliberate connection of metal structure, frame and system grounds so everything sits at the same reference potential. Poor bonding produces mystery symptoms: nuisance trips, tingles at the step and twelve volt gear that behaves differently on generator than on shore power.
Neutral Bond: The single intended tie between neutral and ground, which belongs at the source and nowhere else in the coach. Extra bonds added by a well meaning modification cause protective devices to trip randomly, and they are tedious to hunt down after the fact.
LiFePO4 Battery: Lithium iron phosphate battery chemistry with a built in management board, deep usable capacity and low weight. It requires a charge profile and a cold charging limit the older converters do not provide, so the charging side gets addressed at the same time.
AGM Battery: Absorbed glass mat lead acid battery, sealed and vibration tolerant, still a sensible choice for chassis and house duty. It tolerates the charge profiles already installed in most coaches, and it fails gradually rather than shutting off at a board level.
Battery Monitor Shunt: A precision resistor installed in the battery negative path so a monitor can measure current in and out and report true state of charge. Mount it wrong, with some loads bypassing it, and the display becomes confidently inaccurate, which is worse than having no monitor.
Onan Generator: Common brand of onboard house generator in RVs, feeding coach circuits when no pedestal is available. It is a service item with its own oil, filters, brushes and exercise schedule. The house generator is in scope at this shop, and the chassis engine is not.
Generator Slobbering: Unburned fuel and oil residue weeping from the exhaust of a generator that has spent its life running with almost no electrical load. It is a symptom, not a defect, and it clears up with load and carbon cleanup instead of a parts replacement.
Wet Stacking: The condition behind slobbering, where light loading keeps the generator too cool to burn fuel completely and residue builds in the exhaust. Exercising the unit under real load, not just starting it monthly, is the maintenance habit that avoids this entirely.
Load Bank Test: Applying a known electrical load to a generator to verify it produces rated output under real conditions, not just idles. An unloaded start proves the starter works and nothing more. Load testing is how we confirm output and clear residue in one procedure.
EPA 608 Certification: Federal certification a technician holds to handle refrigerant legally, including recovery from rooftop air conditioning equipment. It matters to an owner because uncertified refrigerant handling is illegal venting, and a documented recovery protects the coach's service records.
LP Certification: The training and testing credential required to service liquefied petroleum gas systems on recreational vehicles, covering piping, appliances and pressure testing. Anyone opening a gas line and handing the keys back should have it, and should test the system before release.
Dogbone Adapter: The short shore cord adapter that lets a coach connect to a pedestal outlet of a different rating. Handy, and also a common failure point, since a heat damaged adapter throws voltage drop symptoms that look like a bad converter or a weak air conditioner.
Base Coat Clear Coat: Two stage refinish where color goes on flat and gloss comes from clear over the top. It is the standard for modern coach finishes because color match, metallic control and repair blending are all easier when the gloss is a separate layer.
Single Stage Paint: Color and gloss in one product, sprayed and done. Faster and often used on utility panels, cargo bodies and older units. It is harder to spot repair invisibly, because any polishing cuts into the color itself instead of into a sacrificial clear layer.
Tri Coat Finish: Three layer system with a ground color, a translucent midcoat and clear over the top. Common on pearl whites found across coach exteriors. Match depends on midcoat film build, so these colors demand test panels before the coach gets sprayed.
Let Down Panel: A test panel sprayed with increasing midcoat passes, each step masked off, so the exact number of coats that matches the coach can be read off the card. On pearl finishes this step is what separates an invisible repair from a panel that reads a shade light.
Spray Out Card: A primed card sprayed with the mixed color and cleared, then held against the coach in daylight before anything is committed. It costs a few minutes and it catches tinting problems while they are still cheap to fix rather than after the whole side is coated.
Blend Panel: An adjacent panel where new color is faded out into existing finish so the eye never catches a hard edge. Blending is real labor with real material cost, and it is the line adjusters most often ask about on an estimate for a large sidewall.
Orange Peel: A finish that dried with a fine dimpled texture instead of flowing smooth, from spray pressure, reducer choice or booth temperature. Light peel polishes out. Heavy peel means sanding the clear back and recoating, so the fix belongs before cure rather than after.
Solvent Pop: Tiny craters where trapped thinner blew through the film as it cured, usually from coats stacked too fast or a bake started too early. It cannot be polished away because the void goes into the film. Flash time discipline is the entire prevention.
Fisheye: Small round craters where the coating pulled away from a contaminant, most often silicone or wax residue. On coaches that have been treated with slick protectants for years, the contamination is deep in the old finish, so decontamination gets extra time up front.
Die Back: Gloss that looks correct leaving the booth and dulls over the following days as the film continues to shrink. It points to too much reducer or an incomplete cure. Buffing early hides it briefly and the panel goes flat again a week later.
Flash Time: The wait between coats that lets solvent leave the film before the next pass traps it. It is not idle time and it changes with booth temperature and humidity. Cutting it to finish a coach on schedule is where solvent pop and die back come from.
Cure Window: The period during which a coating is hard enough to handle but still chemically active, when recoating, taping and sealing behave differently than on fully cured paint. Sequencing decals, trim and sealant inside or outside that window changes how the job holds up.
Downdraft Booth: A paint enclosure that pulls filtered air from the ceiling down through floor extraction, carrying overspray away from the surface being coated. On something as tall and long as a coach, airflow direction is what keeps dry spray off the panel just sprayed.
Bake Cycle: Controlled elevated temperature applied after spraying to accelerate and complete the cure. Ramp rate and hold time follow the coating data sheet, not the clock on the wall. A rushed bake locks in solvent and leaves a finish that never quite hardens.
Mil Thickness: Coating film build measured in thousandths of an inch with a gauge. Too thin and coverage and durability suffer; too thick and the film cracks at flex points and seams. On a coach with several old repaints, measuring first tells us how much can safely be sanded.
Adhesion Promoter: A thin chemical layer that gives coatings something to grip on slick plastics and cured substrates that sanding alone will not key. Skip it on a bumper cover or a plastic trim piece and the paint will lift in sheets at the first pressure wash.
Etch Primer: Acid containing primer that bites into bare metal for corrosion protection and grip. It is the correct first layer on exposed aluminum and steel after collision repair, and it must be topcoated within its stated window or it stops doing its job.
High Build Primer: Thick, sandable primer used to fill sanding scratches and minor low spots so a panel reads straight under gloss. It is a shaping material, not a substitute for bodywork. Over a wavy repair it just makes a smooth surface with the same waves in it.
Guide Coat: A light contrasting dust or spray applied over primer so sanding reveals highs and lows as the block cuts through it. Nothing else shows a long, gentle wave on a sidewall as honestly. It is the difference between straight in the bay and straight in sunlight.
Color Variance Code: The manufacturer's alternate mixing formula for the same paint code, issued because production batches drift. Two coaches with identical codes can need different variants. Chasing the right variant with spray out cards is normal work, not an excuse for a slow match.
Gel Coat Oxidation: The chalky, faded surface of a fiberglass cap or panel after years of sun exposure. The color is still down there under dead resin. Compounding and polishing often bring it back, which is a far smaller job than refinishing the whole cap.
Wet Sanding: Sanding with water or lubricant and fine paper to level a finish without loading the abrasive or burning the surface. Used on gelcoat repairs and on clear before polishing. Grit sequence matters, because skipping steps leaves scratches that no buff will remove.
Cut And Buff: Compounding a cured finish to level texture, then polishing to bring gloss up to match the surrounding surface. This is where a good refinish becomes an invisible one, and it is real hours on the estimate rather than a courtesy step at the end.
Freightliner XC Chassis: Raised rail motorhome chassis used under many diesel pusher coaches, with the frame stepped to clear storage bays. For body work it matters because bay structure, skirt panels and compartment doors all hang off that rail geometry and must be measured to it.
Spartan K2 Chassis: Purpose built motorhome chassis platform found under premium diesel coaches, known for its front end structure and generous service access. Collision work here starts with confirming frame and mount alignment before any cap, skirt or compartment panel is fitted.
Ford F53 Chassis: The stripped chassis used under most gas Class A motorhomes, with the cab structure removed and the coach body built over it. Body mounts, floor structure and the front cap attachment points are what we inspect after any frontal impact on these.
Ford E450 Cutaway: Cutaway van chassis with a factory cab and an open rear, the platform under most Class C motorhomes and many commercial box bodies. The cab to house joint is the critical zone, since that seam takes flex and is where leaks and cracks appear first.
Mercedes Sprinter 3500: Dual rear wheel Sprinter platform used under compact Class C and Class B coaches. Tight body tolerances and unibody style rear structure mean panel and cap repairs need careful fitment. We address the coach body and onboard systems, not the chassis engine.
RAM ProMaster: Front wheel drive cargo van platform popular for camper van conversions because of its low floor and boxy walls. Conversions add roof penetrations, windows and cabinetry, and those additions are usually where water intrusion and panel cracking start.
Workhorse Chassis: Motorhome chassis platform found under a generation of gas Class A coaches still very much in service. Parts sourcing for body brackets and compartment hardware takes longer on these, so we identify the platform early and order before teardown finishes.
Roadmaster Chassis: Chassis platform used under certain diesel coaches, with its own frame rail and suspension layout. Naming it on an estimate avoids ordering body mount and skirt parts for the wrong platform, which is one of the quiet causes of a repair sitting in the bay waiting.
Tiffin: Coach builder whose motorhomes are common in Southern California service bays. Their full body paint schemes and molded caps mean collision repair on these is as much refinish planning as structural work, and matching a multi color scheme drives the paint labor.
Newmar: Builder of higher end motorhomes with heavy laminated sidewalls and complex painted graphics. Repair planning on these focuses on preserving the graphic layout, which usually means blending into adjacent panels rather than cutting a straight tape line.
Winnebago: Long running builder of motorhomes and towables across many price points. Parts availability is generally good, which shortens repair cycle time, but the sheer number of floorplans means verifying the exact model year before ordering skins and trim.
Thor Motor Coach: High volume builder covering many Class A and Class C lines. Their units come through with familiar patterns of cap seam and slide seal work, so a technician who has seen several knows where to look before the moisture meter comes out.
Airstream: Riveted aluminum travel trailers with monocoque shells, where the skin is the structure. Repair is closer to aircraft sheet metal work than to fiberglass panel work: panels are drilled out, replaced and re riveted, and finish work involves polishing rather than paint.
Grand Design: Towable builder with a strong following in fifth wheels and travel trailers. Common repair work on these involves laminated sidewalls, large slide rooms and roof penetrations, so estimates usually cover a system rather than a single damaged panel.
Forest River: Very large towable and motorized manufacturer with many separate brands underneath it. Identifying the specific division and model, not just the parent name, is what makes parts ordering accurate, since components differ across lines built in different plants.
Entegra Coach: Premium motorized brand with heavy insulation packages and full body paint. Refinish work here carries the same expectations as luxury automotive paint, so panel straightness and gloss match get more block sanding and polishing hours than a utility repaint would.
Jayco: Builder of travel trailers, fifth wheels and motorized units seen constantly in Southern California. Their roof and sidewall construction is well documented, which helps when we scope how far a leak has traveled before opening the wall.
Lance: Builder of truck campers and light travel trailers with a reputation for tight construction. Truck campers bring their own repair questions, since the unit flexes independently of the truck bed and takes stress at the tie down and jack mounting points.
GVWR: Gross vehicle weight rating, the maximum the loaded unit is designed to weigh, set by the manufacturer. It matters at the counter because repairs that add material, and owner additions like solar and batteries, both eat into the margin between empty and rated weight.
GCWR: Gross combined weight rating, the ceiling for tow vehicle and trailer together, or coach and towed car. Owners often satisfy each individual rating and still exceed the combined figure, which shows up as hitch, frame and coupler damage over time.
Cargo Carrying Capacity: Often abbreviated CCC, the weight left for people, water, propane and belongings after the unit is built and equipped. It is a small number more often than owners expect, and it shrinks further with every accessory added after purchase.
Unloaded Vehicle Weight: Abbreviated UVW, what the unit weighs as it left the factory with standard equipment and no water, cargo or occupants. Used against the rating to figure real capacity, and it is the starting point when an owner asks how much a repair or upgrade adds.
Tag Axle: The additional non driven rear axle on longer motorhomes, added to carry weight and spread load. It affects turning geometry and rear overhang, and rear cap and skirt damage on tag axle coaches often comes from that long tail catching curbs and driveway ramps.
Kingpin: The vertical pin on a fifth wheel that locks into the tow vehicle hitch and transfers pin weight. Any impact or hard jackknife here loads the front frame section. We check pin box mounting and front cap structure together, not one without the other.
Pin Box: The bolted or welded assembly connecting the kingpin to the trailer frame, sometimes with air or rubber cushioning built in. A bent pin box changes towing height and stresses the front wall, so we measure it before ordering front cap or skin parts.
Coupler: The socket at the front of a bumper pull trailer tongue that latches over the ball. Wear, spread jaws or a bent tongue after a hard stop are safety items, and a coupler that will not latch cleanly holds up delivery of an otherwise finished repair.
Supplement: An additional estimate submitted after hidden damage is found during teardown or repair. Supplements are normal on coach work, because water and impact damage travel behind panels. Documented photos and moisture readings are what get one approved without a second inspection.
Teardown Estimate: A priced inspection where panels, trim and covers come off so the real scope is visible instead of guessed. Collision teardown runs one hour at $210, RV systems estimating is $150, and in depth diagnostic time is one hour at $285, credited toward an authorized repair.
Agreed Value: A policy structure where the insurer and owner set the coach's value in advance, so a total loss settles at that stated figure rather than at a depreciated calculation. Owners of higher end coaches should know which structure their policy actually uses before a loss happens.
Actual Cash Value: Settlement based on what the unit was worth immediately before the loss, with depreciation applied. On an older coach in strong condition, this figure often surprises the owner, and condition documentation is the main lever available to push it upward.
Stated Value: A figure the owner declares at policy inception, which typically becomes a ceiling rather than a promise. Many policies pay the lesser of stated value or actual cash value, so the distinction between the three value structures is worth reading before renewal.
Betterment: A charge back to the owner when a repair leaves a wear item measurably better than it was before the loss, such as a new roof membrane replacing a chalked one. It is negotiable and it should be itemized, not applied as a vague percentage across the estimate.
Diminished Value: The market value a unit loses simply from having a repair history, separate from the quality of the repair itself. Whether it is recoverable depends on jurisdiction and on whether the claim is first party or third party, so ask before assuming it is included.
Total Loss Threshold: The point where estimated repair cost plus salvage value crosses a percentage of the unit's value and the insurer stops repairing. Coaches reach it faster than cars because sidewall and roof work is labor heavy, so an accurate early estimate protects the owner's options.
Salvage Retention: Keeping the unit after a total loss settlement, with the salvage value deducted from the check. Owners do this when they want to repair on their own terms. Title branding follows, so the decision affects resale and future coverage.
Appraisal Clause: The provision in many policies that allows a disputed loss amount to go to independent appraisers, and to an umpire if they disagree. It resolves value disagreements without litigation, and it exists in most policies whether or not an adjuster mentions it.
Right To Appraisal: The owner's ability to invoke that clause when the settlement number and the repair reality do not line up. Invoking it requires a documented, defensible repair plan, which is exactly what a teardown based estimate with photos and readings provides.
Direct Repair Program: An arrangement where a shop agrees to an insurer's rates and procedures in exchange for referrals. It speeds paperwork, and it also means the shop answers to two parties. Owners are entitled to choose a shop outside such a program if they prefer.
OEM Parts: Components sourced from the original manufacturer or its supplier. On coaches this often matters for fit of caps, skins and trim, where an aftermarket equivalent may be dimensionally close but not close enough to line up with adjacent panels and graphics.
Aftermarket Parts: Parts made by a company other than the original supplier. Quality ranges widely in the RV space. We call out on the estimate which lines are aftermarket so the owner can decide rather than discovering it when a panel does not match at the seam.
LKQ Parts: Like kind and quality parts, meaning used or salvage components in comparable condition to what was damaged. Frequently the only realistic source for discontinued coach panels and compartment doors, which makes them valuable rather than a compromise on older units.
Recycled Assembly: A complete used unit, such as a slide mechanism, cap section or compartment assembly, taken from a donor coach. On out of production models this is often faster and cleaner than fabricating, and the estimate should note its source and condition.
Non OEM Crash Part Disclosure: The written notice that an estimate specifies parts not made by the original manufacturer. In California this disclosure is required, and it exists so the owner can question a substitution before the part is installed instead of after it is painted.
Labor Rate Survey: An insurer's collected data on shop rates in a geographic area, used to argue what it will pay per hour. Surveys rarely separate RV and coach specialty work from automotive work, which is the usual root of a rate disagreement on a large repair.
Blend Time: Labor allotted for fading new color into adjacent panels. Formulas often assign a fraction of full refinish time, which underestimates a tall coach sidewall with graphics. Documenting panel size and scheme complexity is how that line gets corrected.
Feather Prime Block: The prep sequence of feathering repair edges, priming, then blocking flat before sealer and color. It is a real line item, not overhead. Skipping or shorting it is why a repair edge becomes visible as a halo six months into sun exposure.
Storage Fee: A daily charge for keeping a unit on the property while a claim is unresolved or authorization is pending. It accrues to whoever ends up responsible, so a stalled claim is not a neutral delay. Prompt authorization decisions keep this line small or absent.
Loss Of Use: Coverage for the cost of substitute accommodation or a rental while the unit is out of service. Coach policies handle it inconsistently and limits are often low, so an owner planning a season around a repair should confirm the limit early in the claim.
Adjuster Reinspection: A follow up visit by the insurer's representative to view newly discovered damage before a supplement is approved. Scheduling one costs days, which is why thorough photo and moisture documentation during teardown often lets a supplement clear without the visit.
Subrogation: An insurer paying its own insured, then pursuing the at fault party for reimbursement. It matters to the owner because a successful recovery can return the deductible, and because the repair file becomes evidence, so accurate documentation serves the owner directly.
First Party Claim: A claim filed with the owner's own insurer under their own policy. Repairs move faster because one carrier controls the file, and the owner usually pays a deductible up front that may come back later if fault is recovered from someone else.
Third Party Claim: A claim filed against another party's insurer, where the shop and owner are negotiating with a company that has no relationship with them. Liability has to be established before repair authorization, which is why these files sit longer before work begins.
Deductible: The portion of a covered loss the owner pays before coverage responds. On coach claims the figure is often high enough that small cosmetic damage is better handled outside a claim, and a priced estimate is what makes that comparison possible.
Proof Of Loss: The formal, often sworn statement of what was damaged and what it is worth, submitted to the insurer. Photographs, an itemized estimate and moisture documentation are what turn a narrative into a defensible filing that an adjuster can act on quickly.

Questions

Questions on this

Why do RV estimates use different words than car estimates?

Because the vehicles are built differently. A car body is stamped steel or aluminum panels hung on a unibody. An RV sidewall is a laminated sandwich of fiberglass, adhesive, foam or luan, and framing, bonded as one piece. There is no automotive word for a bond line failing across four feet of sidewall, so the RV trade uses delamination, and an adjuster trained on cars often has to be walked through it.

If I do not understand a line on my estimate, will you explain it?

Yes, and it is a normal part of the conversation rather than a favor. Call (949) 799-3387 with the line item in front of you. Most confusion resolves in under two minutes because the terms are shorthand rather than jargon, and shorthand expands quickly once someone tells you what it stands for.

Does knowing the terminology change what I pay?

It changes what you agree to, which is usually the same thing. An owner who can read a scope catches the missing operation before work starts, when adding it costs a revision, rather than after, when adding it costs a supplement and two weeks of calendar time.

Still not sure what a line on your estimate means

Read it to us over the phone. Most of these expand in under two minutes once somebody tells you what the shorthand stands for.

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