How long does a body take to decompose in a vault?

When a concrete vault comes with plastic, it can take even 500 years until the body start gets to dirt. Anyone looking to come back to earth, should go with a biodegradable casket/wood caskets and not use embalming. Don’t eliminate cremation, which is the easiest way to turn your body into dirt.

Do burial vaults collapse?

Burial vaults do not prevent the decomposition of the human remains within. Vaults which are installed incorrectly and too tightly sealed may not allow gases generated by the decomposing body to escape. Pressure then builds up within the vault until the vault ruptures, causing the vault to fail.