What does "Es ha'Bayis" refer to?
Rashi: It is the Kodesh ha'Kodoshim.
Malbim: It is the Heichal. It was totally covered with gold.
What is the meaning of "va'Ya'aber"?
Rashi: It is an expression of bolts. Radak - the Targum of "Berichim" is Ivrin.
What are "Ratukos"?
Rashi: They are chains. Gra - the Heichal was taller than the Kodesh ha'Kodoshim. In order that the roof the Kodesh ha'Kodoshim not be seen, there were gold chains from the top of wall [between the Heichal and Kodesh ha'Kodoshim] until the end of the roof, along the entire width of the Heichal, and he covered the chains with gold plates.
Malbim: The wall between the Heichal and Kodesh ha'Kodoshim was not covered with cedar wood (Bava Basra 3b 1 ). In order to cover it with gold, Ratukos were fixed in the rocks, and the gold was on the Ratukos and did not move.
Malbim citing Mahari: The wall between the Heichal and Kodesh ha'Kodoshim was only 20 tall, so the smoke of the Ketores could enter; we can say that the Ratukos were like layers. However, Chazal (Bava Basra 3b) say that the wall was 30 tall.
The Gemara did not say so explicitly, but it is clear there that the rock was one Amah thick. If there were a wood covered with any thickness, it would diminish the interior of the Heichal or Kodesh ha'Kodoshim. (PF)