Case 1

Cause of Defects

The cracking of masonry wall may be caused by one of the following factors or the combination of several factors:

• Insufficient tolerance is provided between the window frame and brick wall.
• Differential structural movement; such as the joint between window frame and wall
• Structural deficiency;
• Drying shrinkage of cementitious materials
• Slight expansion of bricks as they absorb water. Process is not completely reversible as the material dries out and can cause stresses in the wall.

Other reasons include:

• Normal service loads,
• Internal stresses
• Overloading of the structure
• Excessive shrinkage of concrete, which together with a drop in temperature gradient causes a decrease in volume. When this volume decrease is restricted by rigid joints, tensile forces are developed which leads to cracking of the tile multi-layer system. Due to the presence of such differential movements between the tiles and the backing wall, cracks resulted.
• Differential movement as a result of the differential settlement of the building foundation causing structural cracks along the tilework of reinforced concrete walls.

Consequences

If cyclic thermal movement is involved, debris is filling the crack can lead to progressive movement. If left unrepaired, subsequent defects of water penetration and biological growth may occur.

• Dirt may be collected on the cracklines. When rain, this dirt will be carried down to the surface of tiled façade and staining results.
• The cracklines may also permit ingress of water into the backing wall which may cause adhesion failure, corrosion of embedded steel and the formation efflorescence.

One must always be on alert that facades are exposed to external environment under harsh combination effects of changes in (a) temperature, (b) moisture, (c) wind, (d) pollutants.