Abstract: T-shaped building blocks are assembled in a wall structure in horizontal courses of blocks, with alternate ones of the blocks in each course facing opposite directions and with the main body sections of each block overlying the main body sections of the next adjacent blocks. The blocks in the first course are placed on a footing, U-shaped clips tie the overlying portions of the main body sections of the blocks together to form rigid wall sections, and the wall sections are leveled by inserting wedges beneath the bottom course of blocks. Mortar is poured into the vertical openings of the bottom course of blocks to rigidly mount the blocks on the footing. As the wall increases in height, vertical tie rods are inserted internally through the course of blocks to tie the blocks in adjacent courses together. Insulation is placed in the vertical openings in the blocks to reduce the passage of heat and moisture through the blocks in the wall structure.

Abstract: Interfitting building blocks are disclosed of both T-shaped and Z-shaped configurations and both blocks define external slots, internal openings and corner bevels for receiving expandable locking elements. The blocks are arranged in a wall in stacked, overlying relationship in horizontal courses of blocks, and the courses of blocks are locked together with U-shaped clips extending between adjacent ones of the blocks in a single course, and vertically extending laterally expandable locking elements extending through adjacent courses of blocks. Mortar is poured down through the aligned openings in the blocks and the locking elements to hold the locking elements in their expanded positions.