FRP, fiberglass reinforced plastic, is commonly used in the construction of various products. Many types of core materials, including plywood, are laminated between layers of fiberglass, which are then secured and strengthened with plastic resins to make panels or structures.

The result is a very strong panel, and weather resistant on both sides. The problem arises with the edges of the panels, which exposes the end grain of the various laminates. Rarely are these edges completely sealed before the panels' installation, and over time moisture will attack the glues and wood laminations under the fiberglass coating.

This is especially true in trailer construction. On older trailers you will find delaminated areas under windows, at the ends of panels at joints, anywhere an edge of a panel can be exposed to the water. If the caulking and sealant hasn't been maintained, this is where you will find failures.

A delamination will show as a bulging in a panel or loose area that can be moved when is touched. An easy way to test a panel's integrity is to tap it with the plastic handle of a screwdriver. A solid panel will make a sharp striking noise, while a delamination will give off a dull thunking or thud type of noise.

Small areas of delamination can be repaired fairly easily. A large area can also be reskined, but will involve a great deal of labour to effect the repairs. The panels used for interior bulkheads and such, rarely will suffer these difficulties.

I would avoid the purchase of an older trailer with plywood and FRP construction that shows an indication of lamination failures. Any such trailer should be meticulously inspected before a purchase is contemplated. It will be heavier than the newer trailers and always prone to panel failures. It will not hold its resale value as well as an all metal trailer. There are too many good used trailers available in excellent repair, to consider this type of construction.

Gard