FRP laminated onto plywood results in a very strong panel, albeit at a weight penality over other types of construction.

The single problem that can damage the lamination, is a lack of maintenance. Every panel that has an exposed outside opening, is subject to water intrusion. Over time, the interior laminates will seperate and rot, and an expensive repair becomes necessary to save the trailer.

Fortunately this situation can be avoided, by frequent checks of the caulking around the windows and doors that penetrate the panels. This is a very important maintenance with this type of construction, and should not be avoided.

To test for delaminations, take the handle of a screw driver and tap the panel starting a foot or so away from the opening. You want to hear a solid "thunk". When you near the window or door, you do not want to hear a change of the sound. If you hear a softer "thud", you have a serious problem. By moving the impacts around the area, you can determine the scope of the problem. It helps to mark the space with tape or a pencil to determine the actual size of the delamination.

Small areas can be repaired fairly easily, large repairs can involve a whole panel or wall section.