The wall on the left is concrete. The forming technique is called board form. Using a series of wood boards in the forming process allows the wood grain and the widths of the boards to be imprinted into the concrete. Originally this was an early way to form walls, and is used here as an architectural finish. Completed with river rocks in a trough at the bottom of the wall and up lighting to highlight the finish.

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The same structural wall is seen on the floor above in the entry.

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