Missing floor insulation leads to high energy cost.
Hidden wood rot from a leak in the roof flashing lead to the need to remove the wall to install new wood framing.
Missing hot water tank pipe extension to the pressure relief valve can lead to getting scalded with very hot water. Plumbing standards require the pipe extension to end within 6" of the floor or discharge to the exterior.
Failed glazing in a glass sliding door means there is moisture between the glass panels; replacement is the only option.