Can You Build Decks or Platforms on Top of the Shipping Container?

The strength in the shipping container rooftops is not in the actual roof but in the four corner posts. It is not recommended for several people to be on the roof at the same time. The weight range that the roofs can support is from 400lbs to 500lbs. The roof will not collapse, but it most certainly will dent, and dents collect water. Water collection leads to corrosion then leaking. Do not be alarmed if you notice that the roof of your container is dome shaped. This is how they were designed in order to allow water run-off. So if you are considering constructing a roof top deck then you will want to design the deck using the corner posts and sidewalls as the main locations for support of your deck.
Side Note: We have met with several other builders who have built roof top decks on containers by simply welding fencing and strips of metal to the side bars and corner posts and then filling in the corrugated roof with cement. Now we have never done this or have never seen it done, but apparently these builders stand by their work and claim it to be safe. We have built a wooden roof top deck on several containers.
We generally spaced the 1.5x1 steel tubes 18” apart going along the 20ft side of the container roof, 90 degrees from the corrugated steel roof seams.

We used galvanized steel for the railing and welded the railing to the top container, but only on one side due to the sliding steel door opening on the other side.

The deck looks great and is super strong. This deck has a welded frame underneath and is structurally sound. When we jump on it there is very slight movement felt in the container below.