Case 1

Cause of Defects

A good understanding of a joint sealant system is required especially for facade exposed to harsh outdoor environmental conditions subjected to cyclical temperature and moisture changes, thermal shock etc.

For this case, the reasons for the joint failure include:

• Material of poor quality
• Grout or sealant with low adhesive properties or high shrinkage will result in loss of adhesion.
• Inadequate joint width
• Wrong use of materials
• The materials used might be able to provide a strong bond but lack flexibility. In this case, any movement might cause cracks in the joints.
• Poor construction practices
• Tilers did not ensure adequate thickness of the joints by applying the grout flush with the tile face.
• Contact surfaces were not clean before application of sealant and grout.
• Movement joints were not constructed into the render.

Consequences

• Water penetration
• Efflorescence and algae growth
• Plant growth within joint

In certain cases of cracking in tile joint, the crevice formed is large enough for seeds of plants to be deposited within and small plants can be seen growing on the façade surface (Figure 1). The roots of such plant might grow and extend into the tiling layers causing voids or cracks that are present to expand in size.