After watching
the video a few times over, here's my interpretation of the Gigafactory construction plan:
The Gigafactory will be built in 7 "blocks" to form a superstructure that will have 3 floors (1st floor at ground level, a 2nd to-be-added floor at 23.5 ft, and a 3rd floor at 41 ft), will have a 5.8 M sq ft footprint on the ground (source:
this article), and will have a total 17.4 M sq ft of floor space and 24 M sq ft of concrete (including the roof which will be at 71 ft). The current block ("block 1" or "block A") will have a 833,333 sq ft footprint and 2.5 M sq ft total on 3 floors. The Gigafactory will be the largest building in the world by footprint at 5.8 M sq ft, beating out the Aalsmeer Flower Auction at 5.6 M sq ft. However, the largest building in the world by volume will still be the Boeing Everett Building at 472 M cu ft vs the Gigafactory in second place at 412 M cu ft. Another note: the concrete floors will be 5.5 inches thick, so that would be 10.6 M cu ft of concrete or 1.6 B lbs (800,000 tons) of concrete!
Additional thoughts:
1. When I first heard the 24 M sq ft number, I thought that meant they were expanding the factory to an 8 M sq ft footprint (24 M sq ft / 3 levels), however, he only mentions 3 floors (the original 2 plus one to be added between the first and second floors) and when he said that there will be "24 M sq ft of structure," I think that by "structure" he was referring to the 4 levels of concrete (including the roof). So there are 24 M sq ft of concrete (including roof), but 17.4 M sq ft of floor space. Plus,
this article confirms that the footprint will be 5.8 M sq ft, not 8 M sq ft.
2. Initially, the GF was planned to be 10 M sq ft on two levels with a 5 M sq ft footprint. The new plan calls for a 17.4 M sq ft building on 3 floors with a 5.8 M sf footprint. This represents a 74% increase in floor space. In the Q1 earnings call, Elon suggested that they were looking into ways of increasing production by 50 - 100%. This expansion would certainly provide the room necessary for such production increases.