Case 1

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Cause of Defects

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:

For this case:

  1. Tiled walls particularly when not in a sheltered area will experience staining more than if they are being sheltered.
  2. Exposed areas may be more ‘self-cleansing’; but the staining may be uneven, resulting in unsightly patches to elevations.
  3. Dirt stains will be more concentrated at the mortar joints since mortar has a higher porosity and absorbs water quickly to leave behind dirt particles within the joints (Figure 1 and 2).
  4. If sealant is used at movement joints and the sealant begins to fail and become sticky, it will hold dirt until it rains. Dirt is then deposited in streaks down the building, emanating from that point.

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

  • Dirt staining on tiled façades, especially glazed tiled façades can usually be cleaned off easily.
  • Dirt stains that accumulates within the mortar joints are usually not easy to remove unless pressure jets and an abrasive cleaning agent are used. It usually represents a loss in the visual quality of the façade.
  • Overtime, it may affect the overall performance of the building.