So as far as I understand, to go anywhere on the map you need to be able to reach it. The "Place a New Fitting" action space is placed outside the house on the third floor. Logically, we decided that you can't do that action until you clear a path towards it. This is further compounded by the fact that there's a hole outside that according to the rules blocks passage.
But, the rulebook also states that accessibility is also determined by the image on the save sheet where the action is not depicted at all. Any clues on what's what?
I think it's the placement of the "Place a new fitting" action that is a bit confusing. They have placed it on a section that is outside the shelter but looks like it may be part of the shelter. The other board actions are placed on actual shelter spaces where you have to place a character.