Today, people are choosing caskets vault more and more. The reason for this is that the cemeteries may require a vault and a dual casket vault is now considered a good choice. Parents are finding that this option covers all bases, it seals very well in comparison to wood and the cemeteries in most cases, will the not require the family to pay for the additional vault cost and the stress factor this may include.
The materials these vault caskets are made of are usually polystyrene. This is a solid, strong product, and this not made for many other uses in this way other than for caskets. Most are made in the USA. The Elixir Butyl, a putty-like sealant, and is a popular sealer because of the incredible strength it has. It is used in aircraft to seal windows.
If you are considering a vault casket be sure that to contact the cemeteries with your choice so they do not surprise you with any local requirements. It is unusual, but the is best to be sure.