Clark Grave Vault’s dome-shaped design allows air pressure inside the vault to keep water below casket level — just as the air in submerged inverted glass keeps the water from coming up inside.
The box-shaped design causes the casket to soak in water. Liners are often made of porous materials such as concrete, which allows water to pass through, soaking its contents, and compromising its weight bearing strength over time.
A casket will not withstand the weight of the earth’s load or heavy cemetery digging equipment driving over grave. Without the protection of a grave vault, the casket and its contents may be crushed. A depression may appear above ground.