A metal cover was over the top of the furnace flue. Perhaps while the home was empty and under repairs but not removed once completed. This was very hard to see from the ground but from on top of the roof quiet obvious. From inside the home the furnace flue pipe was not well connected to the flue of the home and I had serious doubts that the homes flue pipe was double walled pipe. I asked that it be confirmed that all the furnace piping in the home is double walled pipe.
The metal sheet on top of the flue stack outside was only part of this problem.
crawl space mystery
Under the family room of a home I recently inspected I found a “room” that few people knew was there. Not part of the interior of the basement I found an access behind a fridge. The room is a crawl space that had cracks in the foundation walls on two sides and water lines on the walls that indicate 2 feet of water was here not so long ago. We found what appeared to be minimal cracks (that had been repaired) on the outside walls of this home,but further research indicated a much larger and significant issue. We advised a structural engineer evaluate this and determine the solution.
Please hire a qualified home inspector.