Case 1

Maintenance and Diagnostics

Inspection should be done annually to ensure the buildings are in good condition and to identify necessary repairs in accordance with BS 6150, SS 542 or equivalent. Walls that are lightly soiled should be washed with water and mild detergent. For severe soiling, wash with a strong alkali solution in warm water. The walls should be repainted regularly. Repair hairline cracks by repainting the wall with a flexible sealant/elastomeric paint to seal the cracks. For wider cracks, engage a contractor to carry out repair works. Conduct regular inspections with the aid of paint detectors to identify latent paint problems. When a paint is found to be unsound, remove it. Do not repaint over the blister as the unsound paint has suffered from poor adhesion with the substrate. When necessary, conduct paint adhesion test (pull-off).
Ensure unsound paint is stripped back to sound substrate before a new paint is applied.

Regular inspections should be carried out methodically at regular intervals to detect the defects. Cleaning should be carried out at appropriate intervals of time to ensure the removal of dirt before they stain the structure permanently. A checklist can be helpful to keep track of the defects during the process. The following is recommended for routine cleaning in basement carpark :

• normal mopping up of water ponds using a mop (for small area ponding)
• sweeping up leaves and loose dirt using the above sweepers
• scrubbing should be done on stains that were left behind; such as oil stains
  • Rider sweepers: Larger size is suitable for big area sweeping. Used by town councils for public carparks maintenance. Smaller size sweeper is normally found in residential carparks for smaller area maintenance. Activities carried out by sweeper includes blowing, sweeping and vacuuming of the leaves.
  • Walk-behind scrubber that scrubs and vacuums simultabeously. Suitable for residential carpark maintenance.
• For oil stains, recommended methods of stain removal is to use hot water and pressure jet to clear the surface stains. Scrubbing can be done using normal strong detergent that is mild pH balanced and have ‘degreasing’ properties. The detergents are available in concentrated form and should be diluted according to the specifications indicated.

Efflorescence cleaning can be done using normal high pressure water jet. Epoxy finished carparks are not recommended to have carry out scrubbing activities since the epoxy finish may be damaged as the bristles of the scrubber are hard.

Diagnostics of Defect (see also NDT)

Moisture Meter

Paint Detector

Elcometer