- Each module must have at least one corridor connection and a module can be only a corridor if the builder chooses.
- Each corridor must end in an airlock built to the standard pattern.
- The floor of each corridor at the airlock must be 10 bricks off the baseplate for a regular corridor.
- Additional airlocks can be built at ground level or at multiples of 10 bricks from the baseplate.
- Each airlock requires a cap in the event no modules connect to that particular corridor.