Is de-lamination a big problem? Can Azdel help?

One would have to know how any water that leaks inside the layers affects the adhesive bond. Azdel is not going to save your bacon if water leaks inside the bonded wall composite.

Delamination, although not rare, is not a given occurrence. There are many filon sided trailers that suffer no delamination. The trick is to keep up with sealant maintenance or upgrade to a sealant that doesn't need constant upkeep, like Eternabond tapes.