Fiberglass Repair, in detail

Two failures look alike from six feet away and cost very differently. Gelcoat spider cracking is a web of fine cracks in the pigmented surface layer, usually radiating out from a stress point: a screw hole, a tight corner radius, a mounting boss on the back side of the panel. The laminate under it is sound. Sunlight and thermal cycling did that, and coastal Southern California supplies more of both than the original brochure allowed for. It is a surface repair.

A through crack is a single line, often with a slight step or a dark edge, and it moves when you press either side of it. That is the glass, not the coating. Left open it wicks water into the laminate and the job grows from a panel repair into a panel and substrate repair. The tell is simple and needs no instrument: tap along the crack with a coin. Sound laminate rings. Wet or separated laminate thuds.

Impact repair starts with grinding, not filling. The damaged area gets opened out to sound laminate, which is almost always wider than the visible crack, and tapered into a shallow scarf so new material has surface area to bond to. Filling a crack from the front without grinding produces a repair that telegraphs a line back through the paint inside two seasons of sun, and every owner who has been sold that repair recognises the description immediately.

New laminate goes in from both sides wherever access allows. The back side gets reinforcement: chopped strand mat for conformability over a curve, plus woven roving where the panel has to carry load again, wet out in resin and rolled to drive the air out. The front is built slightly proud, blocked back flat, then primed and refinished. A hole punched through a rear cap by a ladder mount tearing out is four to eight hours. A cracked upper cap with a damaged windshield flange is a different number entirely.

• Grind out to sound laminate and taper a scarf, never a vertical edge
• Chopped strand mat for conformability, woven roving where load has to return
• Back side reinforcement wherever the interior panel can be opened up
• Build proud, block flat, prime and refinish, rather than fill and paint

Two very different constructions share the word fiberglass. A Filon sidewall is thin flat fiberglass sheet bonded to a substrate and framing as a sandwich, supplied on a roll, replaced in sections cut to the framing. A moulded cap is a thick contoured part pulled from a tool, supplied as one piece, replaced whole. The estimates barely resemble each other: a Filon section is mostly labour, a moulded cap is mostly a part with freight attached.

Cap replacement runs thirty to a hundred and twenty hours depending on the coach, and the part travels on a dedicated truck because it cannot be crated small. Fitting is dry first. The cap gets hung, gapped, the windshield opening checked, marker and clearance light locations transferred, and only then bonded and mechanically fastened by the coach maker method before any seam is sealed and refinished.

A moulded cap for a coach that went out of production has a real chance of simply not existing. The tool was scrapped, the supplier closed, or the model ran two years and nobody stocked spares. Owners hear that and assume a sales pitch is coming. The opposite is true: at that point fabrication is faster than sourcing. We take a mould off the undamaged side or off a sister coach, lay up a replacement, and fit it.

That is not a cheap answer and there is no point pretending it is. Fabricating a cap sits near the top of this band. What it does is turn an unfixable coach into a fixable one, and carriers generally accept it once we have documented that the part is unavailable rather than merely inconvenient. Documentation is the whole battle: supplier confirmations in the file, not a phone conversation nobody wrote down.

Restoration is the other half of this trade and it has nothing to do with an impact. Gelcoat on a fifteen year old coach in coastal Orange County goes oxidised and chalky, often crazed across the whole upper sidewall and cap, and worst on whichever side faced south in storage. An owner asks about a repaint. Sometimes the correct answer is that the gelcoat is thick enough to be cut and polished back instead, at detail labour of $95 per hour rather than paint labour, which is a materially smaller bill.

Where the gelcoat has crazed all the way through, polishing only makes the crazing shinier and it returns within a season. Then the surface has to be sanded, sealed and refinished, and we say so rather than selling a polish with a countdown on it. The test is easy to run on arrival: polish one small section and let the owner look at both. That decision belongs to whoever is paying for it, made with the evidence in front of them.

Fiberglass is the line most often questioned on a claim, because an appraiser trained on steel sees a body labour figure that looks high for the size of the damage. The answer is that grinding, laminating and cure time are not the same work as pulling a dent, and that a laminate repair has a cure schedule no shop can compress. So the operations get written out individually rather than as one lump, and each step stands or falls on its own terms.

Blend is the other contested line. A repair in the middle of a sidewall cannot be cut in at an edge that does not exist, so refinish has to carry into the adjacent area to disappear. Adjusters challenge that when the adjacent panel is undamaged. It is also the line deciding whether the repair is invisible in daylight or shows as a soft halo, and arguing for it is preferable to handing a coach back with a visible edge on it.