While reading through an article the other day in a very popular magazine, I came across a listing for persons seeking to install an underground property.  Missile Bases: 20th century Castles has some extremely unique solutions that also apply to the protection against an undead invasion.  Will this modern day approach work against a horde of zombies?
Missile Bases

Of most interest, obviously, would be the underground portion of the home.  Traditionally, zombies in large numbers, though clumbsy, prove time and time again to be dangerous.  They have turned over vehicles and penetrated areas of buildings otherwise thought to be secure. 

Yet this underground structure looks to be very solid.  The entrances could easily be sealed with heavy metal doors, not unlike hatches on submarines.  Plenty of living area is offered, and according to the illustration, almost more exists below ground than above.  There are also further escape routes allowing homeowners to retreat if necessary into deeper recesses of the earth.  There appears to be ample storage space in addition to the ability to add creature comforts so that a family could easily defend their homefront and wait out an attack of the undead.

True, the genious minds behind Missile Bases most likely did not have a zombie epidemic in mind when developing and marketing their product.  However, this could easily provide a safe-haven during times of the undead.

Does anyone see any other potential strengths or even design flaws?