How long did Noah take to build the Ark?

How many years did Noah take to build the Ark?

In Genesis 5 we read:

Gen. 5:32 Noah was five hundred years old, and Noah became the father of Shem, Ham, and Japheth.

Then in Genesis 6 we read:

Gen. 6:13 Then God said to Noah, “The end of all flesh has come before Me; for the earth is filled with violence because of them; and behold, I am about to destroy them with the earth.
Gen. 6:14 “Make for yourself an ark of gopher wood; you shall make the ark with rooms, and shall cover it inside and out with pitch.
Gen. 6:15 “This is how you shall make it: the length of the ark three hundred cubits, its breadth fifty cubits, and its height thirty cubits.
Gen. 6:16 “You shall make a window for the ark, and finish it to a cubit from the top; and set the door of the ark in the side of it; you shall make it with lower, second, and third decks.
Gen. 6:17 “Behold, I, even I am bringing the flood of water upon the earth, to destroy all flesh in which is the breath of life, from under heaven; everything that is on the earth shall perish.
Gen. 6:18 “But I will establish My covenant with you; and you shall enter the ark — you and your sons and your wife, and your sons’ wives with you.

Finally, in Genesis 7 we read:

Gen. 7:10 It came about after the seven days, that the water of the flood came upon the earth.
Gen. 7:11 In the six hundredth year of Noah’s life, in the second month, on the seventeenth day of the month, on the same day all the fountains of the great deep burst open, and the floodgates of the sky were opened.

From these three passages, we can determine the time required for Noah to build the ark.

First, we see Noah began to have sons in his 500th year of life (Gen 5:32). Next, Noah's sons were already alive when the Lord appeared to Noah and gave him instructions to begin building the ark (Gen 6:18). Finally, the flood came in the 600th year of Noah’s life (Gen 7:11).

Therefore, Noah must have spent a maximum of 100 years (and probably slightly less) building the Ark.