Case 2

Cause of Defects

Tiles are often poor at keeping rainwater out, but good at trapping it once it is in. If the background becomes damp, particularly brickwork, then moisture that does evaporate may deposit efflorescence either internally or externally or to both elevations. Where water enters and comes in contact with plaster or concrete then lime staining can occur. The point of entry could be at a defective tile or movement joint.

The water penetration and efflorescence is related to one or several of the following reasons:

• cracks in the tiled façade;
• poor permeability resistance of tiles used;
• inadequate or defective expansion joints;
• improper selection of adhesives.
• cracks at mortar joints
• joints between the brick wall backing are not filled up properly and experienced higher degree of exposure to rain
• high porosity of mortar or brick wall backing
• use of unsuitable tile or grout, unable to withstand the tropical climate or weathering or having high water absorption rates,
• may cause water ingress to the interior of the building after a period of time. According to SS 301 (Withdrawn, refer to ISO 13006 and ISO 10545), only tiles with water absorption of no more than 3% for unglazed and 6% for glazed tiles are allowed to be used on external wall tiling.
• white deposits of tiles salts may be present around the tile edges. This may deteriorate the tiles or mar their appearance.

The mechanism for efflorescence formation is as follows:

• Cracks on tiles or joints will form cervices which will allow water to easily seep through to reach the bedding and render layer behind the tile layer.
• When the water escapes from the façade system, it will carry with it calcium compound and deposit them at locations that permit easy exit of the water.
• As such, leaching is a common problem found along crack line on tiles or joints. The crack line, being a passageway for water, will be more concentrated with water and this might also result in algae growth along crack lines along tiles or joints that are constantly wet.
• Very often, efflorescence is accompanied by algae growth in tile cracks or joint cracks. Figure 1 and 2 illustrates the forming of efflorescence through these cracks.

Persistent efflorescence should be taken as a warning that water is entering the wall and this may cause deterioration of wall materials and have other consequences. If repairs are not done to the localised portion of efflorescence formation, further tile delamination may occur.