Full Fiberglass Panel Replacement When the Substrate Is Gone
Written by Structural Repair Lead, Structural and Frame Lead, OCRV Center. Reviewed by Claims Coordinator
In shortWhen the wood behind the skin has failed across a whole panel, there is nothing left to bond to. The panel comes off and a new one goes on, at $4,500 to $25,000+.
When does an RV need full fiberglass panel replacement?
Panel replacement is the answer when the substrate behind the fiberglass has rotted, crushed or separated across too much area to splice. At our Yorba Linda facility, Rancho Santa Margarita owners get windows and rails removed, the framing repaired, and a new bonded panel fitted and refinished end to end.
- Every window, light, rail and molding comes off before the panel does
- Framing damage is usually found only after the old skin is removed
- OEM sidewall skins run long lead times and drive the schedule
- A discontinued panel may mean a fabricated section instead
- Price range
- $4,500 to $25,000+30 to 120 labor hours at $210 per hour
- Labor rate
- $210 per hourBody and paint department
- Typical turnaround
- 3 to 10 shop weeksPanel lead time, not labor, sets most of this schedule
- Deposit
- 50 percent over $2,000Additional 25 percent at parts arrival on jobs over $10,000
- Facility
- 35,000 square feet, indoor bays that take a 45 foot coach with a wall off
Last verified
There is a point where patching stops being the honest recommendation. When the plywood behind a sidewall has gone to pulp along an eight foot run, when a framing member has corroded through at the bottom of a wall, or when an impact has folded a panel rather than cracked it, there is nothing sound left for new material to bond to. At that point the panel comes off.
This is the largest job in the fiberglass department and the one with the most moving parts. It touches windows, doors, awning rails, clearance lights, decals, interior finish and sometimes the roof edge. It also depends on a part arriving, and panel lead times are the single largest reason these jobs are measured in weeks rather than days.
When a panel is genuinely past repair
Three findings move a wall from repairable to replaceable. The first is substrate failure across a wide area, meaning the plywood or composite behind the skin is soft over most of the panel rather than in one patch. The second is framing damage, since a wall bonded to corroded aluminum has no foundation regardless of what goes on the outside. The third is a fold, because folded laminate has broken fibers along the entire crease and cannot be brought back to a true surface.
Everything short of those three is worth trying to save. We re-laminate walls with separated areas the size of a door, splice substrate under a window bank, and rebuild caps with cracking across a third of their face. Replacement is expensive, it is disruptive, and it depends on a supply chain we do not control, so it is the last recommendation rather than the first.
Everything that comes off before the panel does
An RV sidewall is not a bare surface. It carries windows, an entry door, an awning rail, clearance lights, a compartment door or two, moldings, a city water inlet, a cable port and a decal package that runs the length of it. Each of those is fastened and sealed into the panel, and each has to come off before the panel does. On a wall with three windows and an entry door that is most of a day before the actual removal starts.
Everything that comes off gets tagged and stored, and everything that goes back on gets new butyl, new lap sealant and new fasteners. This is where a panel job either produces a dry wall for the next fifteen years or reproduces the leak that caused the whole problem. Reusing hardened butyl on a window frame you just spent three weeks getting to would be an odd way to finish.
Sourcing a skin and why lead time drives the schedule
Manufacturers build sidewall skins to order and they are large, awkward items to ship. Realistic lead times run from a few weeks to a few months depending on the brand and the model year, and that clock starts when the order goes in with a serial number and a build sheet, not when the unit arrives at the shop. We source and date the panel before we open the wall, every time.
On discontinued panels the options narrow quickly. Salvage yards occasionally produce a usable skin from a wrecked unit of the same floor plan. Failing that we fabricate from sheet stock, matching thickness and surface texture, and plan a seam at a molding line where it can be finished cleanly. That is a legitimate outcome, it just needs to be a decision rather than a surprise.
Note
Bring the VIN, the build sheet and a photograph of the data plate to the estimate. Sidewall skins change within a model year, and window locations two inches off make a panel unusable.
Bonding, seams and getting the wall flat
The new panel is dry fitted first, with every opening checked against the component that goes into it, before any adhesive is mixed. Structural methacrylate or two component urethane is then applied in a planned pattern rather than laid down by feel, since adhesive that pools in one area and starves another produces exactly the hollow spots we set out to eliminate.
Pressure and cure follow. The panel is pressed against the framing and held for the full cure window, and the wall is checked for flat with a long straightedge before the clamps come off rather than after. Where a seam is unavoidable, on a fabricated section or a partial panel, it is placed at a molding line so it can be finished honestly instead of buried under filler that will crack along it later.
The realistic schedule on a panel job
Three to ten shop weeks is the honest range, and the labor hours are not what fills that calendar. Panel lead time, adhesive cure windows, and the framing work that gets discovered after the skin is off account for most of it. A job with sixty labor hours in it can easily run six weeks, and telling an owner otherwise at authorization is setting up a bad conversation later.
For anyone with a trip booked, the useful question at estimate is not how many hours the job takes but what date the panel is expected to land at the shop. That date is the schedule and everything else moves around it. We put it in writing alongside the order confirmation, and if it slips, that gets communicated on the day we learn about it rather than at pickup.
What full panel replacement costs
This is the largest job in the fiberglass department and the range reflects it. A small panel on a single axle trailer with one window in it is a different animal from a full length sidewall on a forty foot fifth wheel with a slide opening, three windows, an awning rail and a full graphics package. Both are on this page and they are separated by ninety labor hours plus a very different parts number.
Parts carry standard markup, sales tax applies to parts and materials, and labor is not taxed. A deposit of 50 percent applies above $2,000 and a further 25 percent is due at parts arrival on jobs above $10,000, which reflects the fact that a sidewall skin ordered for your serial number cannot be sold to anybody else. The written estimate is $150 and is credited in full against an authorized repair.
On cost
Budget for framing repair before we open the wall. It is the most common supplement on this job, it cannot be assessed with the skin on, and pretending otherwise only moves the surprise to week three.
Units we replace panels on
Towables lead this category by a wide margin. Long unbroken wall spans, more openings per foot of wall than a motorhome carries, and outdoor storage between trips add up to exactly the conditions that destroy a substrate. Park models are a category of their own because they never move, so nobody walks the roof edge, and a slow leak has a decade to work before anybody notices anything.
Vintage units land here for a different reason. A 1978 coach may have a wall that is structurally fine and a skin that has simply run out of life, and on those we are frequently fabricating rather than ordering. Our 35,000 square foot facility takes those units indoors for the full duration, which matters when a wall is going to be open for several weeks.
Panel replacement, supplements and total loss thresholds
On a claim, panel replacement is where total loss math starts to matter. A job at the upper end of this range against an older unit with a modest actual cash value can push past a carrier's threshold, and that determination is made on the estimate plus expected supplements rather than on the initial number alone. Owners are better served knowing that possibility exists at authorization.
Where the loss is covered and the unit is being repaired, the framing photographs taken with the skin off are the most valuable documents in the file. A supplement for corroded aluminum that arrives with dated images of the exposed structure gets approved. The same supplement described in a paragraph of text gets questions and a delay measured in weeks.
On the claim
Ask your adjuster to view the unit with the panel off, or at minimum to accept the exposed framing photographs before we close the wall. Nothing in this job is reviewable once new material is bonded in place.
What is included
- Full component removal and tagging
- Windows, doors, awning rails, lights, vents, moldings and hardware come off, are bagged and tagged, and everything that gets reinstalled goes back on fresh sealant.
- Panel removal and substrate replacement
- The old skin and its substrate come off together, exposing framing and insulation for the first time since the unit was built.
- Framing inspection, documentation and repair
- Exposed framing is photographed before anything covers it again, and corroded or bent members are cut out and welded in.
- New panel fit, bond and press
- The replacement panel is dry fitted, adhesive is applied to a controlled pattern, and the assembly is pressed while the bond cures.
- Rebedding and reseal of every opening
- Windows and doors go back on new butyl and every roof edge or corner termination in the work area is resealed.
- Refinish and decal reproductionwhere applicable
- The new panel is refinished to match, and factory graphics are reproduced or replaced where the original set cannot be preserved.
How the work runs
Scope and source the panel
2 to 6 hours
Before anything comes apart we confirm the panel exists, price it, and get a real lead time in writing. On a discontinued skin the conversation shifts to fabrication or salvage, and that decision belongs to the owner before the unit is opened up.
Strip the wall
6 to 20 hours
Every window, door, rail, light, vent and molding is removed, tagged and stored. This alone can take a full day on a wall with three windows, an entry door and an awning rail, and shortcuts here show up later as leaks around reinstalled components.
Remove the old panel and expose framing
6 to 24 hours
Skin and substrate come away and the aluminum structure is finally visible. This is where a job most often grows, because corrosion at the bottom rail is common on any unit that has been holding water long enough to destroy a wall.
Repair structure and fit the new panel
10 to 40 hours
Framing is welded, insulation is replaced, and the new panel is dry fitted with every opening checked against its component before adhesive is mixed. Adhesive is applied to a planned pattern and the panel is pressed and held through its full cure.
Reinstall, seal and refinish
12 to 45 hours
Components go back on fresh butyl and sealant, seams are finished, and the wall is primed and refinished. The unit then sits through a controlled water test before anything is called complete, because the entire point of this job was stopping water.
What this costs
$4,500 to $25,000+
30 to 120 labor hours at $210 per hour, body and paint.
- Paint supplies at $55 per paint hour.
- Body supplies at $5 per body hour.
- Hazmat and disposal $45 flat when chemicals, refrigerant or LP is involved.
- Parts at $100 or less carry 100 percent markup. Parts over $100 carry 35 percent. Special order parts require a full non refundable deposit at order.
- Sales tax of 7.75 percent applies to parts and materials. Labor is not taxed.
- A 50 percent deposit is taken at authorization on any job over $2,000, with an additional 25 percent when parts arrive on any job over $10,000. Final balance is due at pickup.
- A single small panel on a trailer with one window sits near the bottom of this range.
- A full length sidewall on a fifth wheel with framing repair and graphics reproduction sits at or above the top.
- Framing corrosion is the most common supplement and it cannot be seen until the old panel is off.
How estimating is billed
- Written repair estimate: $150, credited in full against an authorized repair.
- In depth diagnostic, scan and programming: $285 per hour, one hour minimum, credited in full against an authorized repair.
- In shop pre purchase inspection: $400 to $1,200 depending on unit size and systems count.
- Insurance walk ins are accepted during posted hours. All inspection and estimating work is performed in shop at the Yorba Linda facility.
What you will notice first
- A wall that flexes visibly when you push on it with a flat hand
- Screws along an awning rail or a window flange that will not hold any torque at all
- A soft, spongy area you can indent with a thumb across a wide section of wall
- Interior wallboard that has swollen, stained and separated along a full seam
- A panel folded or creased from impact rather than cracked
- A distinct bow or belly in the wall visible from the front or rear of the unit
- Persistent mildew smell that returns within days of every attempt to dry the coach out
- Previous repairs stacked on top of each other across the same panel
How this fails, and what we do about it
| Failure mode | How we diagnose it | The fix |
|---|---|---|
| Substrate destroyed across the panel | Probe readings sink across the whole area rather than at a spot, tap sounding is hollow over most of the wall, and the interior panel has failed along its seams. | Remove the panel entirely, replace substrate and any failed framing, then bond a new skin. Splicing into material this far gone leaves the repair sitting on a soft foundation. |
| Corroded aluminum framing behind the skin | Found only once the skin is off. Bottom rail and lower verticals show white powder and section loss where water sat for years against the aluminum. | Cut out and weld in new tube, then rebuild the wall. This is the most common supplement on a panel job and it is the reason we photograph the framing before anything new goes on. |
| Folded panel from impact | The panel has a crease that runs across the wall. Fiberglass that has been folded has broken fibers along the entire crease and cannot be straightened back to a true surface. | Replace the panel. Filling a crease produces a thick, brittle section that cracks along its edges and shows in any reflection. |
| Discontinued panel with no source | The unit is old enough or low enough volume that neither the manufacturer nor the aftermarket produces the skin, and salvage sources come up empty. | Fabricate a section from sheet stock, matching thickness and texture, and plan a seam at a molding line where it can be finished honestly rather than hidden. |
Why it happened
- Years of undetected water entry that destroyed the substrate across a wide area rather than at one point
- A framing member corroded at the bottom of the wall where water collected and never drained
- Impact heavy enough to fold the panel and its substrate together, which cannot be pulled back to true
- Delamination that went unaddressed until the separated area covered most of the wall
- A slide opening cut into a wall that was never properly reinforced, so the panel failed along the cut
- Repeated repairs that added stiffness in patches, moving the failure to whatever section had not been repaired yet
Parts and brands we work with
- OEM sidewall skins and molded caps ordered through Winnebago, Thor, Jayco, Keystone, Forest River and Grand Design channels
- Filon and Lamilux sheet stock for fabricated replacement sections
- Azdel composite and lauan substrate sheet
- Aluminum framing tube and welded repair sections
- Structural methacrylate and two component urethane panel adhesives
- Butyl tape, Dicor lap sealant and fresh fasteners for every component that comes off
What not to try yourself
- Screwing a sheet of new material over a failed wall. The rot underneath continues, the fasteners have nothing to hold, and the added weight accelerates the failure of the framing below.
- Ordering a panel from a photograph without a serial number and a build sheet. Sidewall skins change mid model year and a panel that is two inches off in window location is scrap.
- Removing the old skin before the new one is confirmed and dated. An opened wall in a storage lot for six weeks turns a panel job into a full rebuild.
- Reusing old butyl or old fasteners on reinstalled windows. Every component that comes off gets fresh sealant, and that is not the place to economize on a job of this size.
Which vehicles we do this on
Vehicles we perform Panel Replacement on
StandardStandard fifth wheel repair concentrates on the pin box and upper deck welds, the floor at the step up transition, the front cap above the pin and the roof front radius seamLuxury DestinationLuxury fifth wheel repair covers frame flex at the axle hangers under residential weight, independent suspension components, six point auto level hydraulics and hard flooring at slide thresholdsTravel TrailerTravel trailer repair covers A frame tongue welds, the front cap that takes road debris, the roof front radius seam, sidewall delamination starting at a window corner, and equalizer and axle wearClass A GasClass A gas motorhome repair covers the molded front and rear caps, the vacuum bonded laminated sidewalls, the EPDM roof and the F53 chassis underneathVintage and ClassicVintage coach work means riveted aluminum or stick and tin construction over timber or steel framing, bedded in butyl rather than bondedPark ModelPark model repair treats the unit as a sited structure: frame corrosion and sag from years on blocks, pitched roof and flashing detail, residential window sealing, and moisture trapped behind skirtingNobody has ever been happy to hear this recommendation, so I do it with the panel still on and a moisture meter in my hand. I take readings every twelve inches down the wall and write them on masking tape stuck right there so the owner can see the pattern. When forty readings in a row come back saturated, the conversation about replacement makes itself. And I always say the same thing about framing: I do not know what the aluminum looks like until the skin is off, and neither does anybody else, so we budget for it up front rather than surprising you at week three.
Appendix: questions and answers
- What makes you replace a wall instead of repairing it?
- Three findings. Substrate that is soft across most of the panel, framing that has corroded behind the skin, or laminate that has been folded rather than cracked. Any one of those means new material would be bonding to a failed foundation. Short of those, we repair, because replacement is slower and considerably more expensive.
- What is the lead time on a molded fiberglass sidewall panel?
- Weeks to months depending on the manufacturer and model year, and the clock starts when the order goes in with a serial number and build sheet. We confirm and date the panel before opening the wall. An opened wall waiting on a backordered skin is how a panel job becomes a rebuild.
- Why can nobody tell me about framing damage before the work starts?
- Because aluminum framing sits behind the skin and the substrate, and no meter or camera reads it reliably through both. Corrosion at the bottom rail is common on any unit that held water long enough to destroy a wall, so we budget for it at estimate and photograph it the moment the skin is off.
- What if the panel for my unit is no longer manufactured?
- We look for a salvage skin from the same floor plan first. If none exists we fabricate from sheet stock, matching thickness and surface texture, and place any necessary seam at a molding line where it finishes cleanly. That path is decided with you before the unit is opened, not discovered partway through.
- Do the factory graphics survive a panel replacement?
- Rarely on the panel being replaced. Decals bonded to a skin come off with the skin. We either source the factory graphics package if it is still produced, or reproduce the layout from measured photographs of the unit taken before disassembly. Either way it is quoted as part of the job.
- How do you confirm the new wall is actually watertight?
- A controlled water test after every component is reinstalled and every seam is sealed, with the interior open so any entry shows immediately. Given that the original failure was water, finishing without a test would be leaving the most important question of the job unanswered.
Open a file on this repair
Tell us the vehicle, what happened and whether a claim is open. We will tell you what the scope looks like and what it takes to get you back on the road.
Or call (949) 799-3387