Burial Vaults and Burial Liners
In most traditional funerals, burial vaults and grave liners are generally used. A vault or grave liner is placed into the grave, The casket is lowered into this container during the burial. Burial Vaults or and burial liners (sometimes referred to as grave liners) protect the casket from the weight of the earth above it, and prevent the grave from ‘sinking’ over time as the earth settles.
Grave liners are much less expensive than a burial vault and are typically made of concrete that has been reinforced. Burial vaults are much larger and heavier than a grave liner, and are more expensive.
There are no state or federal laws that require anyone to purchase a burial vault or grave liner. Most cemeteries however, do require that and outer container of some kind is used.
There are companies that sell burial vaults and liners to the public, and in many cases it can be less expensive to purchase it that way than from your local funeral home. Funeral homes are required by Federal Law to use the burial vault or liner (or casket, even) that you purchase from a third party, and cannot require you to purchase only from them.