This two-layer roofing system had started to leak into one of the upstairs bedrooms which initiated the call to us for a repair. We found the second layer to be too old and brittle to effectively service and recommend a full replacement. Upon ripping the roof, we found excessive evidence of poor attic ventilation, causing premature failure of the plywood roof deck. Most of the nails holding the deck had popped and the boards were slowly dry rotting. We ripped the entire deck off the roof and replaced with new plywood which gave us a great, sturdy base to install our new GAF shingle system over top. We added ridge ventilation to the entire house to help prevent this problem from occurring again in the future. The house is now properly ventilated, high and dry, and under ours and GAF's leak-free-guarantee and warranty.