Strength and durability
Shipping containers are in many ways an ideal building material. They are designed to carry heavy loads and support heavy loads when they are stacked in high columns. They are also designed to resist harsh environments - they are transported globally on ocean going vessels or can be covered in road salt when transported on roads.
Modular
All shipping containers are made to the same standard measurements and as such they provide modular elements that can be combined into larger structures. This simplifies design, planning and transport. As they are already designed to interlock for ease of mobility during transportation, structural construction is completed by simply emplacing them. Due to the containers' modular design additional construction is as easy as stacking more containers. They can be stacked up to 12 high when empty.
Transport
Pre-fabricated modular can also be easily transported by ship, truck or rail, because they already conform to standard shipping sizes.
Availability
Used shipping containers are available across the globe. In cases where a company or country receives more containers than it can use to ship in the return directions these containers have no real use, since it is not cost effective to return empty containers to their origin.
Cost
Many used containers are available at a cost that is low compared to a finished structure built by other labor-intensive means such as bricks and mortar - which also require larger more expensive foundations. Construction involves very little labor and used shipping containers requiring only simple modification can be purchased from major transportation companies for as little as $1,200 USD each. Even when purchased brand new they seldom cost more than $6000 USD.
Expandable
The shape and standard measurements of shipping containers make houses that are easily expandable. You can start small and add more containers as needed.
Hurricane-Proof
Either single units or multiple units connected, can withstand MPH winds on a foundation, or 175 MPH winds when easily anchored with pylons. ...extremely solid in Tornadoes or Hurricanes.
Earthquake-Proof
Even in a direct hit, he structure my possibly roll around a little but certainly not collapse. It would be the most perfect safety cocoon in an Earthquake. It would be at least 100 times safer and stronger than a conventional housing structure