How do you get heavy equipment into a building, when you cannot get it up the stairs? A deadman's door is the solution.
Usually, builders have different methods for dealing with heavy equipment, and in commercial buildings, this can be handled by a deadman's door. I wanted to post this photo, because I have never seen one in residential construction. If you have an office building with windows, workers will take out a window if they are doing demolition which has to be removed, or if they need to move heavy equipment into a certain floor. In residential homes, heavy items like the water heater and air heating equipment is moved into place before the roof and walls are installed. When the home is complete, and new equipment is needed, they will move larger, heavier equipment in through attic access points. (Older equipment could be left in the attic, when the crew does not want to deal with it). In commercial buildings with solid walls, you may see a door up high on a wall, and there are no stairs to it. These doors exist to be access points for heavier equipment, which needs to be installed after the building is complete. Movie theaters have them to allow the projectors to be installed. These doors are sealed to prevent anyone from opening them, but the term deadman's door comes from when you would open it and fall out.
The door on this home may be meant to be used with a future stair and/or patio. I had never seen a deadman's door on a home before, so I thought this was interesting. The homeowner was constructing some rooms in the attic, and they were adding some heavy framing. This door became the solution for getting the items into the attic. Good idea, since their framing blocked the original attic entrance, making it harder to move larger items through that opening. Well, you always see something new on each home inspection. Your home inspector , Frank Schulte-Ladbeck