The nethermost chamber was five cubits broad, and the middle was six cubits broad, and the third was seven cubits broad: for without in the wall of the house he made narrowed rests round about, that the beams should not be fastened in the walls of the house.
The lowest room was 5 cubits wide, the middle room was 6 cubits wide, and the top room was 7 cubits wide. Inside the walls, he created small ledges (about 3 feet apart) so the wooden beams wouldn't need to be attached directly to the walls.