Tie beam formation apparatus includes parallel opposed sidewalls defining a channel constructed to receive concrete for the formation of a tie beam. The sidewalls are disposed to become a fixed part of the tie beam. The apparatus further includes mounting structure attached to the sidewalls for holding the sidewalls in the channel defining position. The mounting structure is designed to hold the sidewalls on an upper surface of a block wall and to engage the sidewalls with the block wall at regular intervals. The mounting structure is further designed to allow a flow of concrete into openings in the block wall at spaced apart regular intervals.