How long did Noah take building the ark?
NOAH TOOK ABOUT 40-50 YEARS TO BUILD THE ARK
All verses mentioned are noted below for reference.
When God decided to do away with the wicked humankind during Noah's time, Genesis 6:3 says that the decree was issued 120 years prior to the flood , at the time of the flood Genesis 7:6 says that Noah was 600 years old. Therefore at the time of the issuance of the decree, Noah was 480 years old, Noah was not informed by God of his decision until after he had three sons, which grew up and got married,Genesis 6:18.
Obviously time was required, during the 120 years Noah had a family which helped him build the ark, Genesis 5:32 says that Noah became a father at the age of 500 years , so it was 20 years after God decreed , that Noah and his wife decided to have children.
If we assume that by the age of 510 Noah had his three sons, then allowing for his sons to grow up and get married another 30 -50 years ,Noah would then be about 550 to 560 years old. It was at this time that Noah was informed to build the Ark , Genesis 6:18 says ," 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." Read also Genesis 6:13-18 below
Since Noah was about 550 to 560 years old at the time that God made the covenant with him , and 600 year old at the time of the flood ,it is reasonable then to estimate that Noah took about 40-50 years to build the ark.
Genesis 6:3 (NASB)
3 "Then the Lord said, “My Spirit shall not strive with man forever,
because he also is flesh; nevertheless his days shall be one hundred
and twenty years.”
Genesis 5:32 (NASB)
32 "Noah was five hundred years old, and Noah became the father of
Shem, Ham, and Japheth."
Genesis 7:6 (NASB)
6 "Now Noah was six hundred years old when the flood of water came
upon the earth.
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. 14 Make for yourself an ark
of gopher wood; you shall make the ark with rooms, and shall [a]cover
it inside and out with pitch. 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.
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. 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. 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."