Every delam area on my class C was a result of water intrusion due to previous owners not replacing or caring for the EPDM roof. I've since repaired about 90% of it by removing the top layer of damaged wood then using 1 coating of epoxy resin to strengthen the subsurface then adding another coat and clamping down the fiber board in small sections at a time to get the best results as the stuff has only a 15 minute workable time before curing. The delam bubbling looks much better; not 100% but it's just as strong as it was when undamaged. Still, when it's time to get a new rig, I will be running from delam's.