Case 2
Navigation
- Introduction
- Causes of Defects
- Good Practices
- Standards
- Maintenance and Diagnostics
- Remedial
- Similar Cases
- References
Cause of Defects
- Inappropriate choice of bedding adhesive and tile material
- When excessive concrete shrinkage is restricted by rigid joints, tensile stresses are developed leading to cracking of the multi layer tiling system. When tiles are placed over joints or cracks, the shrinkage causes the tiling system to move in the opposite directions. [1]
- The effect of thermal and moisture causes cyclical tile expansion and contraction. This is very significant if the tiles are large in size. Similarly, if movement joints not sufficiently designed and constructed, the movement of the substrate will also induce stress in the tiling system. Cracks will appear on the tiles if the adhesion between the tiles and the backing is rigid and not flexible.
- Differential settlement of a building’s foundation might cause cracks in the walls. This will in turn induce stresses in the tiling system and cause differential movement between the different layers of the tiling system.
- Water from external sources can seep in through the wall due to the porosity of the tiles
Consequences
- Minor water penetration
- These cracks in tiles provide paths for rainwater to migrate into the building, causing staining to the internal finish of the wall.
- 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.
- Cracking of tiles may also be accompanied by delamination and vice versa. Any differential movement between the different layers in a tiling system will induce shear stress along the interfaces and tensile stress on the tiles. If the adhesion bond between the tiles and the substrate is weak, delamination of the tiles will from the substrate will occur. Otherwise, cracking on the tiles will take place. It is therefore common to see a combination of defects/ failures on a façade.
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.
Falling of objects from facades of tall buildings cannot be compromised.