KJV:
And there was an enlarging, and a winding about still upward to the side chambers: for the winding about of the house went still upward round about the house: therefore the breadth of the house was still upward, and so increased from the lowest chamber to the highest by the midst.
NASB:
The side chambers surrounding the temple were wider at each successive story. Because the structure surrounding the temple went upward by stages on all sides of the temple, therefore the width of the temple increased as it went higher; and thus one went up from the lowest story to the highest by way of the second story.