Exterior Structures are not covered and colonists will need to wear suits while operating or repairing them. They can be joined to either interor or exterior structures via connectors that allow transfer of water and power only.
“"A place to extract Ore from the ground. Needs to be placed at the base of a mountain." Mine can...Mine
“"Simple pad that can be used to expand the base cheaply" Can be useful to create temporary...Base Pad