What is "Ulam ha'Amudim"?
Rashi: It was an Ulam (hall) in front of the pillars, an entrance to the house. Its length was along the width of the house, both were 50 Amos.
Radak: It is called a Beis Sha'ar. It had a dome roof.
What is "v'Ulam Al Pneihem"?
Rashi: It was a tall Ulam on the entire house. Gra - it was 130 Amos long (the length of the house and the width of the lower Ulam in front of the house).
Radak: It was on the four [rows of] pillars on which the house stood (verse 2).
What is the meaning of "v'Amudim v'Av Al Pneihem"?
Rashi: On top of the Kerusos on the lower pillars, he set up other pillars, and beams from pillar to pillar. The [upper] pillars are to weave Tzela'os (walls) from one to another, and the Avim (beams) for a ceiling over the Aliyah. Radak, Malbim - Avim are thick beams (Bava Kama 67a).
Gra: The pillars were covered with planks, and there were beams on top of them.
