Albert Barnes Commentary Ezekiel 41:9

"The thickness of the wall, which was for the side-chambers, on the outside, was five cubits: and that which was left was the place of the side-chambers that belonged to the house." — Ezekiel 41:9 (ASV)

And what was left – that is, the passage (F) between the side-chambers and the temple wall, was five cubits (Ezekiel 41:11).

The place of the side chambers that were within – Within the side-chambers belonging to the house. The seer is first giving the height of the side-chambers (Ezekiel 41:8), and then the breadth, from the outside of the wall of these chambers to the temple wall.