Case 1

Remedial (see also Remedial)

Finding the cause of the problem is crucial before a remedial action can be devised. In this case, the problem lies with the backing screed and hence it has to be dealt with first. Generally, two methods are used to repair the debonding of tiles:

• Retiling the debonded tiles.
• As a more effective and permanent solution, re-cladding or over-cladding the existing tile façade with metal panels or with tiles that are mechanically attached to the building structure is recommended.

(i) Water leakage due to porosity of tiled wall

Water from external sources can seep in through the wall due to the porosity of the tiles. Liquid waterproofing agent can be sprayed onto the tile surfaces. The waterproofing liquid will penetrate deep into the contact surfaces, thus, waterproofing the wall by sealing the pores when it cures by micro-crystallisation. Cleaning of the surface with water jetting to remove dirt particles is normally done before the application of the water repellant. The surfaces must be wiped dry before applying the waterproofing agent.

(ii) Water leakage due to faulty joints

When the source of water leakage is diagnosed to be due to cracks in the joints of the tiles, holes will be drilled into the joints and polymer is injected in them to permeate into the cracks. The holes will then be plugged with hydroplug (modified cement with stronger bonding capability and waterproofing property which expand upon contact with water) to seal the holes and stop water seepage.

Grout Injection

Small areas of hollow tiles may be repaired without the need to remove the tiles:

-Cordon off the affected areas to ensure public safety
-Identify spots of hollow tiles using a tapping test
-Mark the locations clearly
-Drill holes within the joint width closest to the hollowness
-Vacuum clean dust
-Inject grout following similar concept to that for PU injection
-Continue to inject until grout is seen to emerge from neighbouring holes
-Repeat the process for other areas

For cases with substantial tile delamination, it is strongly recommended to consider another cladding alternative that uses mechanical anchorage, and not to rely on adhesives. See “Falling objects from facades“.