What is Yatzi'a?
Rashi (citing Bava Basra 61a): It is the same as Tzela and Tei (cells surrounding the Heichal built into its wall).
What is the meaning of "Es Kiros ha'Bayis Saviv"?
Rashi: Opposite the Heichal and the Devir 1 (Kodesh ha'Kodoshim), he made the Tzela'os outside, to the south, west and north. The end of the verse explains the beginning. He built on the wall of the Bayis, near the wall of the Bayis, a Yatzi'a around. How did he make the walls of the Bayis? For the Heichal and for the Kodesh ha'Kodoshim, he made cells [around them],
Radak: He made cells around the entire Bayis (Heichal and Devir). Afterwards it says how he built them with the walls of the Bayis outside. I.e. the wall of the Bayis was thick below, and narrowed on the outside opposite the cells.
Here, Rashi, the Vilna Gaon and Malbim explain that 'Devir' is the Kodesh ha'Kodoshim, like our verse ("Saviv la'Heichal vela'Devir") implies. Below (verses 19-21), they explain that it is the Amah Traksin, a wall one Amah thick that divides between the Heichal and the Kodesh ha'Kodoshim; verse 20 implies like this. They hold that sometimes the word is used for one of these, and sometimes for the other. (PF)
Why does it say "Saviv la'Heichal vela'Devir"?
Malbim: This excludes the Ulam; there were not cells around the Ulam.
What is the meaning of "va'Ya'as Tzela'os"?
Malbim: He divided the Yatzi'a into three rooms (bottom, middle and top).
What were the cells made of?
Malbim: They were of wood, but the inner wall was the wall of the Bayis, which was of rock.
QUESTIONS ON RASHI
Rashi writes that Yatzi'a is the same as Tzela and Tei. Why does it have three names?
Gra: Yatzi'a refers to the interior hollow. Tzela refers to the wall. Tei refers to the interior and the wall.
Malbim: Regarding the Bayis, it is a Yatzi'a (a room outside a house). Regarding the cedar beams that separated one cell from another, it is called Tzela. Verse 6 discusses the cells in general (their dimensions), so it says only Yatzi'a. Verse 8 discusses the [divisions between] rooms, so they are called Tzela'os. They are called Tei'im only regarding the cells by the gate in the Bayis in [the Nevu'ah of] Yechezkel.
