Case 1

Good Practices

Dampness

Prolonged dampness on a facade is determined, among other, the following:
(1) Rainwater runoff pattern
(2) Water absorption coefficient and texture of the material

Water absorption affecting staining
Source: Flow and Changes in Appearance, 1996

For more information on staining issue on facade, please visit “Staining of Facades“.

Design

The material selection for exposed surfaces, and their regularity and surface texture should be detailed to
prevent moisture retention. Areas prone to high moisture exposure shall be made impervious with adequate waterproofing systems. Also such surfaces should be without impediments (e.g. built-in cabinet, fixed equipment/services) to ensure access for inspection and to ensure ease of cleaning. Access for adequate cleaning should be provided in accordance with BS 8221- 1, SS 509-1 or equivalent. Ventilate to prevent moisture retention on floor/wall/ceiling. For natural ventilation, opening > 5% of floor area. For mechanical ventilation, air exchange rate > 20 air changes per hour, in accordance
with “CP on Environmental Health”.

Construction

Exterior surfaces of porous building material (e.g., cellulose, brick, stone, cement rendering) can develop biological growth. Avoid such growth as much as possible with treatments of anti-algae/anti-fungus solutions and allow to dry before painting/repainting (SS 652: B.5.2.1). Improve ventilation and remove sources of dampness to dry out the substrates as thoroughly as possible during painting works inaccordance with BS 6150, SS 542 or equivalent. Ensure access ducts are connected to the mechanicalventilation system. The exhaust system shall dispel the air directly outdoors.

Plaster

• It is advisable to use fungi resistant plaster in our climate.
• Ensure that the substrate is clean and dry before the the plaster is installed.
• Regular chemical treatment to plaster may ensure that the conditions for algae growth are absent.

Paint

Anti-fungus paint can also be used on the walls.