Mausoleum crypts are typically first sealed with a piece of sheet metal that's sealed along the edge with caulking or glue. After the first seal is in place, the crypt is then sealed with a second seal that's typically made of granite, marble or stone.

Once a casket is placed in the crypt, the space is sealed with an “inner shutter,” which is usually sheet metal. It is sealed with common glue or caulking. After this is completed, the “outer shutter” is placed on the crypt. This is usually marble or granite – whatever facing the mausoleum has to make it pretty.