'Roof' in the Bible

You are to make a roof, finishing the sides of the ark to within 18 inches of the roof. You are to put a door in the side of the ark. Make it with lower, middle, and upper decks.

Behold now, I have two daughters which have not known man; let me, I pray you, bring them out unto you, and do ye to them as is good in your eyes: only unto these men do nothing; for therefore came they under the shadow of my roof.