in a foundation assembly , a moisture barrier is placed on a footing and a foundation wall is on the moisture barrier . the moisture barrier thus isolates the foundation wall from the footing . the footing defines a keyway . the moisture barrier comprises a waterproof layer , a bottom layer attached to bottom side of the waterproof layer , and a top layer attached to the top side of the waterproof layer . the waterproof layer blocks passage of water therethrough . the bottom layer is for attaching the moisture barrier to the footing , and comprises a material that attracts water and binds to cement . the moisture barrier comprises a keyway portion sufficiently flexible and configured to fit the keyway in the footing . when the keyway portion fits to the keyway on the footing , it defines a secondary keyway for receiving a key portion of the foundation wall .