Case 1
- Introduction
- Causes of Defects
- Good Practices
- Standards
- Maintenance and Diagnostics
- Remedial
- Similar Cases
- References
Maintenance and Diagnostics
Consider availability of adequate water supply, drainage provisions and electrical power supply to choose a façade cleaning method. Records of cleaning operations (including photographs before and after cleaning, and drawings of nature of deposits, thickness and patterns) should be kept for buildings of significance in accordance with BS 8221-1, SS 509-1 or equivalent. Maintain the façade in a state as near as possible to its new condition. Ease of façade maintenance can be expressed by the frequency of necessary maintenance operations, labour and supplies necessary for each maintenance operation,
and number of possible ways of removing stains, graffiti, etc., or ISO 7361 or equivalent.
Detect/determine staining of porous substrates by joint sealants (ISO/NP 16938-1). Adopt the recommendations for treatments for controlling organic growth in accordance with BS 8221-2, SS509-2 or equivalent. Repair painted surfaces damaged by wear and tear; wash down; remove defective paint film; apply sealer/primer (if necessary); and repaint in accordance with BS 6150, SS 542 or equivalent. TiO2 only works where there is sunlight. Conventional cleanings are still needed for non-coated areas. For areas coated with TiO2, conduct neutral cleaning annually.
Periodic cleaning with a brush with a stiff dry bristle brush or sponge with a high suction cloth such as a chamois.
For more serious cases, efflorescence can be removed by a dilute acid followed by copious washing.
| Condition of Ceramic Tiled Wall | Cleaning Method |
| Unglazed ceramic tiles Glazed ceramic tiles | Scrubbing with washing soda or tri-sodium phosphate. Rinse well. Use plain water to remove soil. Occasionally for heavier soil use a mild detergent solution, rinse well. |
| Mosaic tiles | Washing with an abrasive cleaner such as brushing can be effective. Pressure blasting can also be considered to wash away dirt trapped at the joints. |
| Efflorescence | Removed by dry brushing or with water and a stiff brush. Heavy efflorescence may be removed with a solution of muriatic acid and scrubbing. Wet the surface well before and after the solution is applied. |
| Mildew | Remove with a dilute solution of chlorine bleach in water |
| Biological growth | Use a weak acid such as vinegar. |
Table 1: General cleaning of tiled walls
Diagnostics of Defect (see also NDT)
Finding the source of water ingress into the facade system is most crucial. The following methods are recommended:
Thermography can be used to identify the position of cracks. A range of crack widths, representing mechanical damage, has been induced under controlled laboratory conditions. The method is based on the characteristics of heat flow phenomenon, in a conductive medium of specific geometry, which is intended to model predetermined boundary conditions.
Microwave tomography is a technique to measure the moisture of various materials based on the relatively high dielectric constant of “water” in comparison to the dielectric properties of the material. An electrical field (microwave) is applied to the material, and the microwave induces oscillations of bipolar molecules (i.e., water). Water molecules will reflect and absorb an electrical field during oscillations. A higher electrical field reflected indicates higher water content.
The technique is non-destructive and applicable to wood, brickwork and concrete. The uniqueness of this technique is its ability to measure moisture content at various depths up to 110 mm, allowing the plotting of a 3-D contour of moisture content and facilitating the tracing of the water source.
