Repairing delamination

I really depends on where the delamination is located and how badly the substructure is rotted. If it is under a window for example you are better off removing the window first and putting wedges between the outer FG skin and the wet substrate and allowing that section to dry first before attempting to bond the skin back to the substrate. This way you can actually see how bad the luan is rotted underneath. There are a number of expensive products that are highly viscous like Git Rot or Water glass that you can use to penetrate the luan. It is cheaper to just use an epoxy and add acetone which will thin it down to the same viscosity as these other products. The acetone will flash off quickly leaving just the epoxy bond. Another reason for removing the window is to reseal it to prevent water from entering that area again.