Why do walls buckle or bow?
Bowing, leaning or bulging in external walls are a result of insufficient lateral restraint. Walls tend to be rather high but extremely slender structures and this slenderness ratio leaves then vulnerable to thrusting or buckling forces. In construction restraint is provided by strapping external walls to floor diaphragms and by the brick-bonded connection of the buttressing partition walls running that run at right angles. Problems often occur when the restraint between the external walls and the floor joists and partitions are defective or are missing, as is often the case in older buildings.
How do Lateral Restraint Ties work?
Remedial lateral restraint ties are retrofit tie rods that reconnect the facade of a building back to its main structure to enhance resistance to thrusting and buckling forces. Some of these tying systems are designed to tie the external wall to the timber joists of the structural floor diaphragm or to stud walls.
Others constraining systems are designed to reconnect and strengthen masonry wall junctions to transfer lateral forces back to buttressing walls.
The combination of both restraint types helps to form small box-like structures within a larger structure, thus increasing lateral restraint and stabilising the external wall.