# Glossary of RV and Repair Terminology

> This glossary defines the vocabulary that appears on estimates, claim correspondence and repair discussions without ever being explained. It covers construction and materials, roofing and sealing, electrical and systems, body shop process, and insurance terminology, using the meanings a technician or estimator actually intends.

Source: https://ocrv.biz/glossary/
Business: OCRV Center, 23281 La Palma Ave, Yorba Linda, CA 92887. (949) 799-3387. Serving Tustin, California.

## Why does this vocabulary matter?

Because an estimate is a technical document written in shorthand, and most owners are handed one without a translation. Knowing that a supplement is expected rather than alarming, or that delamination describes a bond failure rather than a cosmetic blemish, changes the questions you ask and the decisions you make.

It also changes how a claim goes. Describing damage to a claim intake representative in the correct terms determines whether your file gets a virtual photo assignment or a field appraiser, and that assignment type determines everything downstream. The words are not decoration.

The definitions below reflect how these terms are used in this shop, on real estimates, at the posted rates on the [prices page](/prices/). Where a term has a looser meaning in casual use, the working definition is given rather than the dictionary one.

## How are these vehicles actually built?

**Laminated sidewall**: A wall built as a bonded sandwich: exterior skin, adhesive, foam or block insulation, aluminum or wood framing, and interior panel, pressed as one unit. It is strong as an assembly and weak once any layer separates.

**Stick and tin**: The older construction alternative: a wood or aluminum frame with corrugated aluminum sheet screwed over it and fiberglass batting between. Heavier and less rigid than lamination, but far easier to open, repair and reskin.

**Delamination**: Failure of the adhesive bond inside a laminated panel, so the layers separate and the surface bubbles, waves or sounds hollow. It spreads outward from the failure point and cannot be fixed by patching the skin.

**Luan**: The thin plywood layer used inside laminated panels as a substrate for the interior surface and as a bonding face. It absorbs water readily, which is why intrusion into a laminated wall spreads much further than the visible stain.

**Filon**: A brand name used generically for the smooth fiberglass reinforced exterior sheet bonded to many laminated sidewalls. It is the shiny outer skin most people picture when they think of a modern coach exterior.

**Gelcoat**: The pigmented outer resin layer on a molded fiberglass component such as a front or rear cap. It is the finish and the weather barrier, and it chalks, crazes and cracks with age and impact.

**Cap**: The molded fiberglass front or rear end of a coach, usually a single large piece incorporating compound curves, lights and often a windshield opening. Cap repair runs $750 to $12,000 while full replacement runs $4,500 to $25,000.

**Substrate**: Whatever sits behind the visible surface: luan, foam, framing, plywood. Damage assessment is really substrate assessment, because the outer skin only reports a fraction of what happened.

**Aluminum skin**: Riveted or bonded aluminum sheet used as an exterior surface, most famously on Airstream trailers. Panel replacement is $2,500 to $25,000 and is its own discipline, closer to aircraft practice than to automotive body work.

**Composite panel**: A bonded panel using a synthetic core rather than wood, common on newer coaches and commercial box bodies. It resists rot far better than luan and requires different adhesives and different repair techniques.

**Subfloor**: The structural floor deck beneath the finished flooring, usually plywood over frame members. Soft or spongy floor is a subfloor symptom, and replacement is a substantial operation because everything above it has to come out first.

**Soft spot**: A localized area of flex in a wall, roof or floor indicating that the substrate underneath has absorbed water and lost strength. It is the most reliable field indicator of hidden water damage.

**Chassis**: The frame, running gear and drivetrain the body is built on. On a motorhome the chassis and the house are two separate engineering problems that meet at the mounting points, which is exactly where collision forces concentrate.

**Coach**: Trade shorthand for the living body of a motorhome, and by extension the whole vehicle. When an estimator says the coach is racked, they mean the body structure has been pushed out of square.

## What do the roofing and sealing terms mean?

**EPDM**: A synthetic rubber membrane widely used as a recreational vehicle roof surface. Flexible, repairable and prone to chalking with age. Membrane replacement across all types runs $3,500 to $18,000.

**TPO**: A thermoplastic roofing membrane, whiter and stiffer than EPDM, that can be heat welded at seams. It is common on newer units and behaves differently under repair.

**Lap sealant**: The self leveling compound applied over roof seams, terminations and penetrations to shed water. It is consumable, it shrinks and cracks over years, and inspecting it is the single highest value maintenance habit an owner can build.

**Butyl tape**: A non hardening sealing tape installed under mounted components such as windows, vents and trim. It is the actual seal on most penetrations, while the visible caulk is a secondary barrier.

**Termination bar**: The metal strip that clamps a roof membrane edge down at a wall or transition, sealed over the top. A lifting termination bar is a common and easily missed entry point for water.

**Penetration**: Any hole through the roof or wall envelope for a vent, antenna, air conditioner, solar mount or plumbing. Every penetration is a potential leak and each one has its own sealing method.

**Roof recoat**: Cleaning, preparing and applying a fresh coating over a sound membrane along with resealing seams and penetrations. It runs $750 to $4,500 across 4 to 20 hours and extends membrane life rather than replacing it.

**Water intrusion**: Water entering the structural envelope through a failed seal, seam or penetration. It is the primary long term failure mode for this entire category of vehicle and the reason sealing is treated as structural work.

**Moisture mapping**: Metering a wall, ceiling or floor at grid points to establish how far water has spread and where it is likely entering. The readings are recorded by location and date, which makes them evidence as well as diagnosis.

**Slide topper**: The fabric awning mounted above a slide room to shed water and debris off the slide roof when it is extended. Replacement runs $450 to $1,800, and a failed topper is a common cause of slide roof water damage.

**Wiper, bulb and D seal**: The three common slide seal profiles. Wipers sweep the slide face, bulb seals compress at the perimeter, and D seals seal against the sidewall. Replacement across the set runs $400 to $3,000.

## What do the systems and power terms mean?

**Shore power**: External 120 volt supply from a campground pedestal or a household connection. Faults here typically involve the inlet, the cord end, the transfer switch or the distribution panel rather than anything downstream.

**Transfer switch**: The device that decides whether the coach draws from shore power or the generator, switching automatically when one becomes available. A failed transfer switch presents as intermittent total power loss and diagnostics run $285 to $1,500.

**Converter**: Converts 120 volt shore or generator power down to 12 volt to run the house systems and charge the batteries. Distinct from an inverter, and confusing the two sends a lot of diagnostic effort in the wrong direction.

**Inverter**: Converts 12 volt battery power up to 120 volt so household outlets and appliances work without shore power or a generator. Replacement runs $750 to $4,500.

**House battery**: The battery bank powering living systems, separate from the chassis starting battery. Replacement runs $500 to $5,500 depending on chemistry and bank size.

**LiFePO4**: Lithium iron phosphate battery chemistry, now common in house banks for its depth of discharge and cycle life. It requires a compatible charging profile, which is why a battery swap often becomes a charging system conversation.

**MPPT**: Maximum power point tracking, the controller type that extracts the most usable current from solar panels across varying conditions. Solar installation runs $1,500 to $12,000 across 8 to 40 hours.

**Schwintek**: An in wall slide mechanism using vertical gear racks driven by synchronized motors. Compact and common on lighter units, and sensitive to synchronization and alignment, which is why slide service spans such a wide range.

**Through frame slide**: A slide mechanism using rails and rams mounted through the floor structure rather than in the wall. Typical on heavier rooms, and repair usually means access from underneath.

**Leveling system**: Hydraulic or electric jacks that level and stabilize the vehicle when parked, often with automatic control. Service runs $350 to $6,500 and faults are frequently sensor, pump or control related rather than mechanical.

**LP system**: The propane supply, regulation and distribution serving the furnace, water heater, cooktop and sometimes the refrigerator. Service and leak repair is certified technician work and runs $285 to $2,500.

**Absorption refrigerator**: A refrigerator that runs on LP or electric heat with no compressor, common in older units. It requires level operation and adequate ventilation, and diagnosis differs completely from a residential or compressor unit.

**Macerator**: A pump that grinds waste tank output so it can be moved through a small hose. Replacement runs $400 to $1,800 and failures are frequently caused by what was put into the tank.

**Hydronic heat**: A heating system that circulates heated fluid through the coach for both space heating and domestic hot water, common on higher end units. Service runs $750 to $8,500.

**Driver assistance calibration**: Realignment of radar and camera systems after body, windshield or suspension work so they aim where the software expects. Scan and recalibration runs $275 to $1,800 and is documented with pre and post scan reports.

## What do the body shop process terms mean?

**Teardown**: Authorized disassembly to expose concealed damage so the true scope can be documented. Removed parts are tagged and stored beside the vehicle so a reinspection never requires a second disassembly.

**Blend**: Feathering new color into an adjacent undamaged panel so the transition is invisible under all light. Blending is why refinishing a single damaged panel frequently involves two or three panels of work. Blending runs $500 to $5,000.

**Masking**: Covering everything that is not being refinished, and on a segmented coach scheme with multiple accent colors and hard boundaries, this is a major share of the paint hours rather than a preliminary.

**Remove and install**: Labor for taking components off to gain access and putting them back, distinct from repairing anything. On interior access work it is frequently larger than the repair itself and it is itemized separately on our estimates.

**Structural pull**: Correcting frame or body geometry with anchoring and measuring equipment before any panel is refitted. Frame and structural work runs $750 to $20,000 and is certified technician work.

**Panel replacement versus repair**: The per panel decision, made on hours against cost. If repairing takes more hours than replacing plus refinishing the new part, replacement wins. If the part is discontinued, repair wins regardless of hours.

**Hazmat line**: The $45 flat charge applied when work involves chemicals, refrigerant or LP requiring regulated handling and disposal. It appears when the work actually involves regulated material rather than by default.

**Paint supplies**: Materials calculated at $55 per paint hour covering primer, sealer, base, clear, reducer, hardener, masking materials and booth consumption. Tying it to hours keeps a short blend from subsidizing a full respray.

**Body supplies**: Materials calculated at $5 per body hour covering abrasives, filler, adhesives, butyl, sealants, one time use fasteners and weld consumables. Automotive style estimates routinely omit the entire category.

**Special order part**: A component ordered specifically for your vehicle that the supplier will not accept back. It requires a full deposit at order because it is model specific and not resellable.

## What do the insurance terms mean?

**Supplement**: A second estimate filed after teardown covering damage that could not be seen from outside. On structural work it is routinely larger than the original estimate and it is the normal shape of the job.

**Actual cash value**: What the vehicle was worth immediately before the loss, built from comparable sales and adjusted for condition and equipment. It drives total loss decisions and it is where valuation disputes concentrate.

**Agreed value**: A policy that fixes the settlement amount in writing at inception, so a total loss pays that figure without a comparables argument. Common on vintage, custom and high value units.

**Total loss replacement**: A policy that replaces the vehicle with a new comparable unit rather than paying a depreciated figure, usually only within a defined age window from original purchase.

**Betterment**: A charge back to the owner when a genuinely worn part is replaced with a new one. Legitimate on tires at half tread, frequently misapplied by formula to items with no wear relationship such as structural framing.

**Depreciation holdback**: Money withheld until a repair is complete on a replacement cost policy, then released. Some policies never release it, which is worth checking on your declarations page rather than at settlement.

**Diminished value**: The reduction in market value that can remain after a correct structural repair, simply because the vehicle now has a damage history. Recoverability depends on your policy, the at fault party and the jurisdiction.

**Appraisal clause**: A provision in nearly every policy for resolving disputes about the amount of a loss. Each side appoints an appraiser, the appraisers select an umpire, and the resulting valuation binds.

**Salvage retention**: Keeping a vehicle the carrier declared a total loss. The salvage value is deducted from the settlement and the title is branded permanently, which affects both insurability and resale.

**Declarations page**: The policy summary listing coverage types, limits, deductibles and whether you hold agreed value, total loss replacement or actual cash value. The single most useful document an owner can bring to a shop.

**Direct repair program**: An agreement where a shop accepts negotiated rates and process concessions in exchange for steered volume and faster approval authority. It suits passenger car work and fits laminated forty five foot bodies poorly.

**Loss of use**: Rental or accommodation reimbursement while a vehicle is being repaired, capped by day and by total. Those caps were written for repairs measured in days, not structural coach work measured in months.

## Questions

### What is the difference between delamination and a soft spot?

Delamination is a bond failure between the layers of a panel, which shows as bubbling, waviness or a hollow sound. A soft spot is loss of substrate strength from absorbed water, which shows as flex underfoot or under hand pressure. They frequently occur together, since water is the usual cause of both.

### Why do estimators care so much about sealants?

Because on these vehicles sealing is structural rather than cosmetic. Water intrusion is the primary long term failure mode for the whole category, and the seams that fail are always the invisible ones. Lap sealant and butyl are consumables with a service life, not permanent fittings.

### Is a converter the same as an inverter?

No, and confusing them misdirects a great deal of diagnostic effort. A converter steps 120 volt shore or generator power down to 12 volt to run house systems and charge batteries. An inverter steps 12 volt battery power up to 120 volt so household outlets work without shore power.

### What should I ask if I do not understand a line on my estimate?

Ask which labor category it falls under, how many hours it carries, and what specifically that operation accomplishes. Every line on our estimates has a rate, an hour count and a purpose, and any of the three should be explainable in a sentence. If it cannot be, that is worth knowing too.

## Related

- [Frequently Asked Questions](https://ocrv.biz/faqs/)
- [Prices and Posted Rates](https://ocrv.biz/prices/)
- [Insurance Help](https://ocrv.biz/insurance/)
- [Our Process](https://ocrv.biz/our-process/)
- [Repair Cost Calculator](https://ocrv.biz/cost-calculator/)
- [Resources](https://ocrv.biz/resources/)
- [Services](https://ocrv.biz/services/)