Case 4
- Introduction
- Causes of Defects
- Good Practices
- Standards
- Maintenance and Diagnostics
- Remedial
- Similar Cases
- References
Maintenance and Diagnostics
Natural Stone is basically a porous material that absorbs spills and stains if left untreated. Cleaning stone with quality impregnating sealer will prevent most stain from damaging the investment. When using stone as the external façade, the recommended sealers are the ones that give the repellency against weathering and ultraviolet rays. Once sealed, the stone will be more protected and hence with proper cleaning, it will retain the sealer longer and keep your stone protected without damaging the stone’s natural beauty.
Regular cleaning should be performed to cleanse the granite stone of any spores of algae or fungi.
Do not use acid-based cleaners (below pH 7), high alkaline (above pH 9) cleaners or strong degreasers for maintenance.
It is also recommended to reapply sealers to stones every 2-5 years to ensure continued performance of granite cladding.
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.
See also Staining of Facades