Deck Repair - not attached to stringers

[FLexpat]

Man that sucks!
My deck was only bonded to the stringers by blobs and drizzles of 'potter putty' on the tops of the stringers - since the tops of the stringers were not parallel with the underside of the deck, the gap ranged from ~1/4" to about 1.5". If the deck is flexing a whole lot I would suspect the deck core is separated from one or both skins - it may be rotted as well. The core is probably a combination of 3/8" balsa and plywood squares. A good panel with a 3/8" core is pretty stiff.