Knowles built and installed the airtight bunker years ago.
"Everybody wants a secret room in their house - everybody does - either to hide your things or to hide yourself if you have to," Knowles said.
Knowles is one of a growing number of self-proclaimed survivalists around the country. He even appeared on National Geographic's television show "Doomsday Preppers."
Knowles explains he'll survive a nuclear war, and most people won't.
"Bad things could happen," Knowles said.
And according to Knowles, his foxholes are selling like hotcakes all across America and he's even getting orders from other countries.
Anyone can custom-order their own foxhole from Knowles' website, he'll even help you install it under your living room.
It's not just for a zombie apocalypse, he says a lot of people use it for storage or a wine cellar.
"This will hold about 1,300 bottles of wine," Knowles said.
He's outfitted his with food, water, a pump to suck and filter outside air, and the foxholes can even have plumbing.
Knowles is currently working on a 20-foot foxhole designed for businesses and schools in tornado zones. He says it will cost around $50,000.