Case 1

Good Practices

Design

Specify the use of a local green-certified breathable paint system to reduce trapped moisture and to
avoid wetness and dampness of basement walls. Fungi-resistant paint is recommended. Avoid the use of alkyd based paint on concrete surfaces that may lead to saponification (i.e., the formation of oily patches) in accordance with BS EN 1504-2 or equivalent. The most probable reason for paint blistering in a basement is due to moisture entrapment within the concrete substrate beneath the paint film. With time
when the paint loses its elasticity, it may be too brittle to withstand the forces imposed by the moisture and air entrapments, resulting in hairline cracks and eventually peeling and flaking. The performance of a paint system in a basement requires adequate adhesion to the substrate. Surface preparation of the substrate is hence critical. Specify the paint system and the criticality of surface preparation and paint application in accordance with SS 542.

Construction

Ensure adequate curing of the substrate before paint application to avoid shrinkage cracks. Permissible
moisture content should refer to the paint manufacturer’s recommendation. Clean the surface and use clean tools. Avoid prolonged storing, inadequate stirring, use of incompatible thinner/solvent, or mixing with leftover paints from previous batches in accordance with BS 6150 and SS 542 or equivalent. If it is brush-applied, apply the second coat at right angles to the first coat to help eliminate pinholes and avoid chemical attacks in accordance with BS 8000-0 and SS 150 or equivalent. Ensure that coatings, preferably
locally green certified, are always applied in a minimum of three coats. The material should possess
some degree of flexibility (i.e., be elastomeric) to reduce the risk of cracking due to thermal/moisture movements in accordance with BS 8000-0, SS 150, SS 542 and SS 554 or equivale

Paint

Material

• Avoid vibrant colours that will show traces of discolouration easily. If it is necessary to use such colours, select colours that are more stable and are more resistant to weathering.
• Deterioration/ erosion of pigment may also be due to low quality paint or paint with water sensitive pigments.Use weather resistant paint or paints that are more stable. Application of paint system should follow closely to the manufacturer’s specifications to achieve best results.
  Use only appropriate coat as recommended by the manufacturer.
• Prepare receiving surface and apply appropriate sealer to protect the paint.Select a colour that is more stable and use an appropriate coating system.

Sunshading devices

• Installation of sun breaking devices can reduce the amount of UV light attacking the painted facade.

Water repellent and surface coating system

Clear water repellents are most effective at reducing the amount of water absorbed by the brick masonry. Thus, they can help reduce staining and fungi growth caused by moisture absorption, particularly on highly absorptive masonry.

Surface preparation is important. The surface on which the coating is to be applied has to be:

• cleaned by grinding, chemical etching or blasting.
• dried by allowing the wall to cure for a few days before the coating is applied. During rainy periods, the walls should be protected with a plastic covering so that the drying is not interrupted.

Other surface protection systems include:

• Impregnation systems:
  • Prevent penetration of water and solutions into brick without hindering the escape of internal moisture from concrete
• Materials used:
  • silicon organic solutions
  • resins
  • oils
• Sealers
  • Heavy barrier against penetrating solutions but may hinder the escape of internal moisture
• Materials used:
  • epoxy resins (EP)
  • polyurethane resins (PU)
  • unsaturated polyester resins (UP)
• Coatings
  • compared to sealers, they provide additional protection against mechanical influence.
  • increased resistance to diffusion of internal moisture
• Materials used:
  • plastic modified cement systems and resins