We opened up an outside wall in our family room because of suspicious looking drywall. After removing the insulation, we found that the sheathing behind the wall frame is all wet and moldy smelling. The area that is wet is 6' x 6'. We think it is leaking because the roof needs replacing. The outside has brick. Would we be able to replace the sheathing on the inside, removing the studs and replacing the bottom plate and bracing (both of which are showing signs of deterioration and mold)? Or is the only way to replace it to tear down the brick on the outside to get to it? Any input would be appreciated.