וַיִּ֤בֶן אֶת־היצוע [הַיָּצִ֙יעַ֙] עַל־כָּל־הַבַּ֔יִת חָמֵ֥שׁ אַמּ֖וֹת קֽוֹמָת֑וֹ וַיֶּאֱחֹ֥ז אֶת־הַבַּ֖יִת בַּעֲצֵ֥י אֲרָזִֽים׃ (פ)
Rashi on I Kings
Five amohs high. Of each one. Therefore, their total height was fifteen amohs besides the thickness of the ceiling.
Rashi on I Kings
And he covered the Beis Hamikdosh. That is the upper covering of the roof, and the covering [=והספון] mentioned above that was the ceiling of the upper story.