Case 2

Cause of Defects

For this case:

1. Tiles fall off from the façade and leaves ‘pockets’ where dirt particles can accumulate (Figure 1).
2. During rainfall, such ‘pockets’ alter the runoff pattern, slowing the speed of flow.
3. The rainwater will carry the dirt particles and deposit them below such areas. Hence, heavy streaks of dirt stains can be observed around these areas.

Design issues that may cause the defect:

1. The required chemical properties of the tiles, such as chemical resistance and resistance to staining and water absorption may not be stated in the specifications. The person who prepares the specifications may not have taken into consideration the environmental condition and the maintenance method to be used when drafting the specifications.
2. Wrong choice of adhesive may cause reaction to occur between the tiles and adhesive leading to staining. Multiple joints in a tiled façade allow dirt accumulation in the joints.
3. Maximise the use of large tiles.

Construction issues that may cause the defect:

1. Joints may not be fully filled leading to ingress of water and dirt accumulation.
2. Poor quality grout, wrong selection of grout, poor workmanship and improper cleaning after tile installation are possible causes of dirty or bad pointing. [4]
3. Insufficient protection of completed tiling surface after installation may result in the surface coming into contact with incompatible compounds leading to staining.

Consequences

• The tiled wall becomes aesthetically unpleasing.
• Overtime the overall performance of the wall may be affected since more tiles may debond when dirt and rainwater seeps behind the tiles and cause the bonding agent to deteriorate.

Staining on a facade has a lot to do with the pattern of rainwater runoff, which in turn is dependent on the facade configuration, colour, texture, as well as the “roughness” and “water absorption” properties of the materials used: