This is one good reason why you have your home inspected prior to signing on the dotted line. We found this after we had to remove all the storage in front of the access panel. Home owners have never been up in their attic since buying it. Roof leaks and blocked soffit vents have been the culprit for this mold showing up. We advised our client to have a contractor increase the ventilation rate after they rip off the roof decking and replace the roof.
Cost renegotiated was $6,000.00. The seller gave all $6,000 towards a new roof and placed a new layer of insulation inside the attic. Cost for home inspection $249.00. $6,000.00 towards fixing damaged roof... priceless!