Case 3
- Introduction
- Causes of Defects
- Good Practices
- Standards
- Maintenance and Diagnostics
- Remedial
- Similar Cases
- References
Maintenance and Diagnostics
Maintenance
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 is necessary to maintain the aesthetics of tiled façades. A neutral cleaning agent should be adequate if a periodic maintenance schedule is performed.
Diagnostics of Defects (see also NDT)
- The range and degree of the staining can be assessed by visual inspection.
- Petrography can also be used to analyse staining occurring on stones.
- Scanning electron microscopy (SEM): determines the surface characteristics of stones.
- Mercury porosimetry to determine the porosity or pore space of the stone to allow water to be present. It is one of the most useful methods to investigate the porous structure of solid samples in a quantitative way. It provides reliable information about pore size/volume distribution, particle size distribution, bulk density and specific surface for most porous solids regardless of their nature and shape.
- Thermography is used to determine the presence of water retained within the granite panel.
See also Staining of Facades