On Wednesday, September 27, 2017 at 3:40:56 PM UTC-5, Woody wrote:

Structure failure like termites eating your sill plate or house is falling into a sink hole?


BINGO!

I'm betting he has a termite problem. He can repair that crack
until the Second Coming and it will continue to crack until he
gets the problem causing the crack repaired.

(Speaking from experience from my brother's house.)