As described in Edward R Ford's The Details of Modern Architecture vol. 2, the second design of the Eames House was not actually entirely built out of the same materials (plus one additional beam) from their first design.
From The Details of Modern Architecture vol. 2:
A. Trusscon OT 125 steel bar joist (RJ-1) supporting rood with metal deck above.
B. 12 WF 27 steel beam (RB-1) and 12 I 16.5 steel beam (RB-2) at edge supporting joists.
C. 12 C 10.6 edge channel (RJ-2).
D. Trusscon OT 141W steel bar joist (FJ-1). The joists span the long dimension of the box so that they can be lowered where the deck occurs. The floor joists are more closely spaced than the rood joists because of their greater load.
E. 14 WF 43 steel beam (FB-1).
F. 12 C 10.6 edge channel (FB-2).
G. 2 steel columns.
H. Story-high truss from steel angles.
I. 8 x 4" I section at studio. Although the framing of the studio is similar in the final design, it is much lighter.
J. Studio floor framing of 6 x 4" I section with Ferroboard metal deck.
K. Retaining wall.
A. OT 125 roof joists 7' 4" oc (RJ-1). Numbers in parentheses refer to elements from the initial design.
B. 4 x 4" x 10 lb. column partially embedded in concrete wall.
C. OT 141 floor joists 1' 10" oc (FJ-1).
D. Two-story 4 x 4" x 10 lb. column. Although columns occur in the first design, there are only two, whereas the second uses 18.
E. 12 C 10.2 channel at second floor to support floor joists. Although a similar member is used in the first design, it was of a different length and with different connections.
F. Concrete retaining wall.
G. Studio framing similar to house.
H. 3 x 3 x 1/4" continuous steel angle at top. This was a truss part in the initial design.
I. Nonstructural 4 x 4" columns at ends. These do not support beams or joists, only windows.
As shown by the above details, the oft-repeated story from Esther McCoy of how Charles Eames completely redesigned Case Study #8 and used the same materials (with one additional beam) is in fact an over-exaggeration. If the working drawings of both houses are compared, it reveals that although there are clear correspondences between many of the old and new components, many new components were required, such as 38 4-inch H columns and base plates. Similarly, the 12-inch-deep edge channels at the floor although of the same cross section as used in the first design, are of different lengths and have different openings.