The side rooms were arranged one above another in three levels of thirty rooms each. There were ledges all around the wall of the temple to serve as supports for the side rooms, so that the supports would not be fastened into the wall of the temple itself.

1 Kings 6:5
Against the walls of the temple and the inner sanctuary, Solomon built a chambered structure around the temple, in which he constructed the side rooms.

1 Kings 6:6
The bottom floor was five cubits wide, the middle floor six cubits, and the third floor seven cubits. He also placed offset ledges around the outside of the temple, so that nothing would be inserted into its walls.

1 Kings 6:10
He built chambers all along the temple, each five cubits high and attached to the temple with beams of cedar.

Ezekiel 41:5
Next he measured the wall of the temple to be six cubits thick, and the width of each side room around the temple was four cubits.

Ezekiel 42:6
For they were arranged in three stories, and unlike the courts, they had no pillars. So the upper chambers were set back further than the lower and middle floors.

And the side chambers were three, one over another, and thirty in order; and they entered into the wall which was of the house for the side chambers round about, that they might have hold, but they had not hold in the wall of the house.