The upper chambers were narrower because the galleries took away more space from them than from the lower and middle stories of the building.

For they were arranged in three stories and had no pillars like the pillars of the courts; therefore the upper chambers were set back from the ground more than the lower and middle stories.

He builds His upper chambers
in the heavens
and lays the foundation of His vault
on the earth.
He summons the waters of the sea
and pours them out on the face of the earth.
Yahweh is His name.