A Eucalyptus Limb Through a Cabover Bunk Floor

A Class C cabover is a fiberglass or aluminum skinned box built on aluminum tube framing, cantilevered forward over the chassis cab and supported at the rear by the main body structure and at the front by nothing at all. It is designed to carry a mattress, two people and its own weight while resisting road induced flex. It is not designed for a concentrated impact from above.

The limb struck about eighteen inches back from the front face of the cabover, roughly on the centerline. That location is the worst case, because it is the point of maximum bending moment for a cantilevered structure with no support at the front. The load broke the membrane and roof deck immediately, then continued down into the framing.

Two transverse roof bows split at the impact point. The load then transferred into the bunk floor, which is a thin plywood panel on light framing, and punched through it, dropping limb material into the bunk area itself. Then the residual load spread to the corners of the cabover box, opening the joint between the cabover side panels and the roof panel on both sides, and cracking the fiberglass at the front corner radius on the driver side.

Photographs of the limb in place before removal, with the vehicle identifiable in the frame. That establishes cause beyond any question. Then a set of photographs after the limb was cut away and removed, showing the damage in daylight. Then the National Weather Service wind advisory for the date, which the owner printed the same week.

The other useful item was the owner call to the carrier the same day. A same day report on a dated weather event is about as clean as a first notice of loss gets, and the adjuster was on site within four days. Their initial estimate was $11,600 and it covered the roof and the visible fiberglass, which was reasonable given what could be seen from outside.

The supplement after teardown was $9,300, covering the split bows, the cabover framing, the bunk floor, the opened corner joints and the windshield surround work described below. It cleared in seven business days with a photograph sequence of 41 images tied line by line to the added scope, and one reinspection visit that took about twenty minutes because the coach was staged torn down with the measurements posted next to it.

The bunk mattress and the interior cabover finish panel came out first, which exposed the underside of the roof structure. Both split bows were fractured cleanly through the tube wall, and a third bow immediately aft showed a crease on its lower face indicating it had yielded without fracturing. All three came out.

Insulation across the entire cabover was wet, not from the impact but from the eleven days between the event and intake, during which the coach sat with a tarp and two rain events happened. Moisture readings ran 19 to 36 percent across an area considerably larger than the impact zone, because water had run rearward along the bows and down into the front of the main roof.

The finding that expanded the job was the windshield surround. The cabover front face sits directly above the windshield, and the load had pushed the lower cabover front rail downward by about three sixteenths of an inch, which loaded the top of the windshield opening. The windshield itself was cracked from the upper passenger corner. Once we measured the opening, the upper rail needed correction before glass could be installed, and that is structural work in an area with a lot of adjacent trim and wiring.

Structure first and in a specific order. The cabover front rail was corrected back to its designed position with the windshield opening measured continuously during the pull, because that opening is the reference that matters. Then the three roof bows were replaced with matching tube section, bonded and mechanically fastened to the side rails.

Then the bunk floor: new plywood panel with its supporting framing repaired, bonded and fastened, and this is the point where we added something. The original bunk floor framing was two longitudinal members. We added a third on the centerline, which costs very little and meaningfully stiffens a floor that was marginal to begin with. That is a judgment improvement rather than a restoration, and it was disclosed and authorized.

Then the corner joints, which were opened, cleaned, re bonded with structural adhesive and mechanically fastened before the exterior skin repair. Then new insulation, new interior panel, roof deck panel replacement across the impact area, and a new membrane across the entire cabover roof and forward four feet of the main roof, with a new termination bar bedded in non sag sealant and fastened at four inch centers.

Total repair was $20,900. Labor came to 147 hours: 38 structural, 21 roof membrane and sealing, 24 water damage and insulation, 16 interior, 12 electrical inspection and repair, 8 glass and trim, and 28 body and refinish. Body and paint bills at $210 per hour and mechanical and electrical at $260, with a $45 hazmat charge because sealant and adhesive chemicals were involved.

The refinish deserves a note because it is where the number grew more than the owner expected. This coach had a three color graphic scheme with a metallic mid tone running across the cabover and back along both sidewalls. Repairing the front corner radius meant refinishing the cabover front and both cabover sides, and carrying the metallic meant blending back into the first three feet of each sidewall, plus recreating the graphic break. Twenty eight hours plus paint supplies at $55 per hour times paint hours.

The calendar was 19 working days. Three were the drying period after wet insulation removal, verified with a meter rather than a schedule. Two were waiting on the windshield, which is a specific part for this cab and had to come in. Nothing else waited. The owner drove it out with a new membrane across the whole front of the coach, which is a better roof than it had before the tree fell on it.