# Class C Motorhome Repair, Starting at the Cab Over

> Class C motorhome repair usually starts at the cab over bunk, because the seam where the coach cap meets the original van or truck cab is the single most reliable leak on the vehicle. Work runs from about $1,500 for seam and seal repair to past $90,000 for structural rebuilds. Body and paint labor is $210 per hour.

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| Business | OCRV Center |
| Service area | Westminster, Orange County, Southern California |
| Facility | 23281 La Palma Ave, Yorba Linda, CA 92887 |
| Phone | (949) 799-3387 |
| Email | info@ocrvcenter.com |
| Typical range | $1,500 to $90,000+ |
| Source | https://ocrv.online/vehicles/class-c-motorhome/ |

Class C motorhome repair means working on two vehicles that were never designed to be one. A coach builder takes a cutaway chassis with a factory cab still attached, bonds a fiberglass and laminated body to the back of it, and caps the whole thing with a bunk that sticks out over the cab. Westminster owners bring us that joint over and over, because it flexes every mile and it is the first thing to leak.

## The Cab Over Bunk Is the Whole Story

On a Class C, the coach body extends forward over the factory cab and forms a bunk. To do that, the builder cut into or sealed against the original cab roof and bonded a fiberglass cap over the top. You now have two structures with different stiffness, joined at a seam, cantilevered out over the front axle where every bump works it. Nothing else on the vehicle sees that combination of load and exposure.

When the seam opens, water does not stay at the seam. It runs rearward along the bunk floor, soaks the plywood and framing under the mattress, and eventually shows up as a stain on the interior ceiling well behind the actual entry point. By the time an owner sees the stain, the bunk floor is usually already soft across a two or three foot span.

The right repair depends on how far it went. A caught early seam job is stripping the old sealant, inspecting the bond and fasteners, and re bedding the joint, roughly $1,500 to $4,000. Once the bunk floor is soft, the cap comes up, framing and decking are replaced, and the job runs $6,000 to $18,000 depending on how far back the rot traveled.

- Press the bunk floor at the front corners, not the middle
- Look for a ceiling stain behind the bunk, not at the seam
- Check the underside of the cab over from inside the cab
- Meter the front sidewall corners where the cap wraps down
- Inspect marker light and clearance lamp gaskets on the cap face

## Where the Coach Meets the Factory Cab

The other joint that defines this vehicle is the vertical one at the back of the cab, where the coach body was bonded to the cutaway. On many builds there is a rubber or sealant filled gap there specifically because the two structures have to move relative to each other. Owners often see that gap opening and assume a shop did a bad job. It is usually working exactly as designed until the sealant hardens and cracks.

A collision that hits the front of the coach body loads this joint directly. We check it for displacement on any front or corner hit, because a coach body that has shifted on the chassis will never seal again no matter how much sealant goes into the gap.

This joint is also why a Class C corner repair needs both trades. The cab side is automotive sheet metal with published procedures. The coach side is bonded laminate and fiberglass. We do both in house, which matters because a shop that only does one will fix its half and hand the other half back to you.

## Rear Wall Separation and the Ladder Nobody Checks

The rear wall of a Class C carries the spare, often a ladder, sometimes a rack, and always the rear cap seam. Fasteners through that wall into laminated panel loosen over time, and each loose fastener is a water path into the core. A rear wall that has begun to separate shows as a slight step or shadow line where the sidewall meets the rear cap.

The repair sequence is to remove everything mounted through the rear wall, open the seam, evaluate the framing behind it, rebuild what has gone soft, then re bond and refinish. Where a ladder or rack is going back on, we add backing plates so the load spreads instead of concentrating on four screws in foam.

## Sidewall Lamination on a Shorter Body

Class C sidewalls are built the same way as a Class A wall, thin fiberglass skin bonded to foam and framing, but the body is shorter and the wall is broken up by more openings: entry door, windows, refrigerator vent, bay doors. Every opening is an edge, and every edge is where a bond line can start to release.

The good news is that a shorter wall usually means a smaller repair area. Injection is more often viable on a Class C than on a 43 foot coach, because the delaminated zone tends to stay local to the opening that caused it. A window corner delamination caught within a season is often a $1,500 to $3,500 job.

The bad news is that owners on this class often defer it. Heat cycling in Southern California will grow a small bond failure across a wall in a couple of summers, and once it crosses an opening the repair changes from injection to section replacement.

## What a Class C Repair Actually Costs

Our posted rates are the same for every vehicle: body and paint at $210 per hour, mechanical at $260, diagnostic at $285 credited against an authorized repair, and a $150 systems assessment that is also credited. Parts carry 100 percent markup at or under $100 and 35 percent over $100, plus 7.75 percent California tax on parts and materials.

A worked example on the most common job we see: cab over seam opened, bunk floor soft across roughly three feet, no framing rot beyond the front two members. That is typically 30 to 44 hours of body labor at $210, so $6,300 to $9,240, plus $900 to $2,200 in decking, framing, sealant and refinish materials. Add paint if the cap surface has to be refinished.

Anything above $2,000 takes a 50 percent deposit so the material order goes in the day you approve it. On a Class C the long lead item is almost always a molded cap or a model specific window, and ordering a week earlier is often a week off the calendar.

- Seam reseal caught early, roughly $1,500 to $4,000
- Bunk floor and framing rebuild, roughly $6,000 to $18,000
- Window corner delamination injection, roughly $1,500 to $3,500
- Rear wall separation with rebuild, roughly $4,000 to $12,000
- Corner collision across cab and coach, commonly $12,000 to $40,000

## Frequently asked questions

### Why does my Class C leak over the cab even though I resealed it?

Because the leak is usually not where the stain is. The cab over cap is bonded to the factory cab at a seam that flexes constantly, and water entering that seam runs rearward along the bunk floor before it finds a path down through the ceiling. Owners reseal the spot above the stain, which is often two feet behind the actual entry. We water test the vehicle from the front working back, and moisture map the bunk floor with a meter, so the repair goes where the water is getting in. Resealing the wrong seam is the most common thing we undo on this class.

### How do I know if the bunk floor is rotted?

Press hard on the bunk floor at the two front corners with the mattress out, not in the middle where the framing supports it. Any give, sponginess or crackling means the decking has taken water. Then look at the underside of the overhang from inside the cab for staining or a wavy line in the fiberglass. A musty smell in the bunk after the coach has been closed up is another reliable sign. Our $150 systems assessment includes metering that area, and it is credited against the repair. Caught early it is a seam job. Caught late it is a floor and framing rebuild.

### What does Class C motorhome repair cost?

The range runs about $1,500 to past $90,000. A cab over seam reseal caught before the floor softens is $1,500 to $4,000. A bunk floor and framing rebuild is commonly $6,000 to $18,000. Rear wall separation repair runs $4,000 to $12,000. A front corner collision that involves both the factory cab and the coach body typically lands between $12,000 and $40,000. Structural rebuilds with extensive water damage go higher. Body and paint labor is $210 per hour, mechanical is $260, and authorized repairs above $2,000 carry a 50 percent deposit.

### There is a gap opening between the cab and the coach body. Is that bad?

Not necessarily. On many Class C builds there is an intentional expansion joint at the back of the cab, because the automotive cab and the coach body are different structures that move relative to each other. That joint is filled with a flexible sealant that has a service life, and when it hardens and cracks the gap becomes visible. Normal service is to cut the old material out and re bed the joint. What is not normal is a gap that has changed since a collision, or one that is wider at the top than the bottom. That points at the coach body shifting on the chassis, which is a structural repair.

### Can you repair the fiberglass cap instead of replacing it?

Usually yes. Fiberglass takes repair very well when the laminate behind the damage is sound. We grind the damage out to a taper, lay structural glass on the backside where access allows, rebuild the front face, fair the surface and refinish. That is typically a third to half the cost of a molded cap. Replacement is the right call when the cap has separated from the cab over a large area, when the framing under it has failed, or when the damage runs into the roof seam. On older Class C units the cap may also simply not be available anymore, which makes repair the only real path.

### My coach was hit on the front corner. Do I need two different shops?

No, and that is exactly the problem most owners run into. A Class C front corner hit damages automotive sheet metal on the cab side and bonded fiberglass laminate on the coach side, plus the joint between them. An automotive shop will fix the cab and hand you back a coach that still leaks. An RV shop without collision capability does the reverse. We do both under one roof, which also means one estimate, one set of measurements and one party responsible for the joint in the middle. That joint is where the repair either holds or fails.

### How long does this kind of work take?

A cab over seam reseal is three to six business days. A bunk floor and framing rebuild is two to four weeks. Sidewall injection is roughly a week including cure and refinish. A corner collision across the cab and coach is four to eight weeks, driven mostly by whether a molded cap or a model specific window has to come from the coach builder. When a part is far out and the coach is drivable, we do the teardown and documentation, place the order, and return it to you until the material lands. That keeps your season rather than parking it here.

### Is a Class C worth fixing if it has water damage?

It depends on where the water went and what the unit is worth. Water confined to the cab over bunk is a contained repair and almost always worth doing, because the rest of the coach is unaffected. Water that has traveled down a front sidewall into the floor structure is a different conversation, since the repair scope grows with every foot of soft framing. We meter first and give you a real map of the wet area before you commit to anything. If the numbers say the repair passes the value of the coach, we will tell you that up front.

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OCRV Center performs all work in shop at 23281 La Palma Ave, Yorba Linda, CA 92887. Serving Westminster and Orange County. Call (949) 799-3387 or email info@ocrvcenter.com. Posted labor rates are published at https://ocrv.online/prices/.