Depending on how long ago you bought your home, contact your home inspector and ask him to review his report and the conditions at the property. Without reading his actual report and knowing the conditions at the time of the inspection, it's difficult for me to go beyond that recommendation at this time.
I had an instance several years ago that was somewhat similar but didn't involve fire damage. I simply couldn't get into the attic because the access was in the laundry closet. The washer and dryer installation prevented me from setting up a ladder, and that wasn't half of it. I don't think the washer and dryer had been used in several years because the closet was full of everything. I barely even saw the attic access. Nonetheless, when my Clients called to complain about the conditions in the attic, I referred them to Item 4 and Figure 1 in the report, which told them that I didn't get into the attic and that they should have the attic inspected before close of escrow. Even offered to do it (at a cost, of course--I charge for my services). No one ever did anything, so I didn't think I could be held responsible for advice not taken.