Genesis 6:16
6:16 Make a roof for the ark and finish it, leaving 18 inches 1 from the top. 2 Put a door in the side of the ark, and make lower, middle, and upper decks.
1 tn Heb “a cubit.”
2 tn Heb “to a cubit you shall finish it from above.” The idea is that Noah was to leave an 18-inch opening from the top for a window for light.