Fiberglass
Fiberglass Repair
In short: Fiberglass on an RV is a laminate rather than a solid panel, so a crack that looks like a surface problem is usually a delamination problem underneath, and repairing only the surface guarantees it comes back.
- Typical range
- $800 to $12,000+
- Labor hours
- 4 to 60 hours
- Updated
Fiberglass on a recreational vehicle is not what most people picture. A boat hull is a thick solid laminate. An RV sidewall is a thin outer skin, often under two millimetres, bonded to a substrate of luan plywood or foam, with framing behind that. It is a sandwich, and it gets its strength from the bond between the layers rather than from the thickness of any single one.
That construction is why fiberglass repair on an RV is a different trade from fiberglass repair on a boat, and why the intuitive fix, filling the crack, is the wrong one.
What a crack is actually telling you
Fiberglass does not crack because it is weak. It cracks because it flexed past its limit, and a bonded laminate only flexes when the bond behind it has failed or the structure supporting it has moved.
So a crack is a symptom. The causes we find behind them, in rough order of frequency:
Delamination. The skin has separated from the substrate over an area, so it is unsupported and flexes as an unsupported membrane until it fails. This is the most common by a wide margin.
Water-softened substrate. Luan that has been wet is no longer structural. The skin over it is effectively unsupported even where the bond survives.
Structural movement. A frame or cage member that shifted in an impact, or a sidewall that has racked, puts the skin into a load it was not designed for.
Impact. A genuine puncture from a branch, a road hazard, a low overhang. This is the one case where the damage really is local, and it is the minority.
Stress concentration at an opening. Cracks radiating from a window corner, a door corner or a compartment opening. The opening is a stress riser and something is loading it.
Repairing the crack without addressing which of these caused it produces a repair that fails again, typically within a season, typically over a longer run than the original.
How the repair runs
Assess first, including behind the skin. Tap testing and moisture metering across the affected area and well beyond it, because the delaminated zone is almost always larger than the cracked zone.
Open the area. The skin is cut back to sound bonded laminate. This routinely means removing considerably more material than the visible damage suggests, and it is the step where owners get uncomfortable. Removing less means repairing it again.
Replace failed substrate. Wet or crushed luan comes out and new material goes in. Where framing is involved it is repaired or replaced first.
Re-laminate. New glass laid up in layers, wetted out, and bonded to the surrounding sound laminate with a tapered overlap rather than a butt joint. A butt joint is a stress riser, which is to say a future crack.
Fair and finish. Filled, blocked flat, primed. Fairing is slow and it is what separates a repair you cannot find from a repair you can see from thirty feet in raking light.
Gelcoat or paint. Colour matched to the vehicle as it is now, not to the original formula.
What it costs
| Job | Typical range | Labor hours |
|---|---|---|
| Single crack or puncture, local repair and blend | $800 to $2,500 | 4 to 12 |
| Crack with delamination behind it | $2,500 to $6,500 | 12 to 32 |
| Large section, structural involvement | $6,500 to $12,000+ | 30 to 60 |
| Fabricated replacement section, discontinued panel | Quoted after assessment | Varies |
Body labor is $210 per hour and body supplies calculate at $5 per body hour. Paint labor is $210 with supplies at $55 per paint hour. Full rates are on the pricing page.
What we work on
Class A, B and C motorhome caps and sidewalls, fifth wheel front caps and sidewalls, travel trailer shells, toy hauler walls and ramp surrounds, teardrop and A-frame camper bodies, truck camper shells, molded fiberglass trailers, and fiberglass on commercial and mobile business builds including food trucks and mobile medical units.
Front and rear caps are the most common single item. A cap is a large moulded part that takes road debris, low overhangs and every parking mistake, and on most coaches it is also the single most expensive body panel to replace, which is why repairing one properly is usually the better economics.
Gelcoat, paint and the colour match problem
A gelcoat finish that has been in California sun for eight years is not the colour it left the factory. It has chalked and shifted, unevenly, more on the roof and the south-facing side than elsewhere.
This means matching to the factory colour code produces a visible patch. We match to the vehicle as it is, and where the surrounding finish is too degraded to match against, we say so and recommend refinishing a larger area. That is a more expensive answer and it is the one that produces a vehicle you are not annoyed by.
Related work often runs alongside: delamination repair when the bond has failed over a large area, panel replacement when repair is no longer economic, and paint and refinishing when the finish work extends beyond the repair area.
Estimates are $150 and credited back against an authorized repair.