Deflection and cracking in unreinforced concrete block basement walls can be repaired by a process of placing reinforcement and concrete in the hollow cores of masonry. The method is said to work for walls up to 5 inches out of plumb. An average residential installation takes 3 to 4 days and is done by a three-man crew inside the basement.
Three- to four-inch-wide openings are cut into the cells of distressed block walls, at points no farther than 4 feet apart. The cells of the block are then cleaned out down to the footing through a hole made in the wall at the very bottom of each point. Two reinforcing bars of suitable diameter and grade of steel are inserted at each point. A threaded rod is then inserted into the top of the cutaway wall opening and run up through a drilled hole in the sill plate where it is fastened with a nut. Metal anchors are installed which securely fasten the joists and sill plate together.
Form boards are then placed over the open cells and 3000 psi concrete is poured into the open cells, encasing the reinforcement, until each point is completely full. With the use of water-reducing agents, the form boards can be removed early enough so that the surface of the concrete can be leveled and roughened to resemble the texture of adjacent blocks. Joints are tooled into the new concrete to present a continuous joint appearance.