Facade Protection

Mineral-based building materials are widely used for their excellent durability. An important characteristic of these mineral construction materials is their porous surface structure and hydrophilic nature. Because these building structures readily absorb water which remain a constant source of serious damage in buildings because it transports harmful substances and microorganisms into the heart of these building structures. Therefor exterior walls are quickly discolored or damaged by rain and the expected life of the building will be reduced. These drawbacks make façade protection essential.

Water repellent materials help to preserve substrates and to increase the expected life of building materials by degreasing the damaging effects of moisture, pollutants, and chemical attack. Water repellent materials are designed to protect facades against damp. They repel water, allow walls to breathe, and assists in reducing heating costs. This phenomena is best illustrated on the Figure 1:

 

Properties of water repellent materials:

1-Water vapour and carbon dioxide are able to escape from the wall (breathing).

2-Rainwater, aqueous chemicals such as acid rain, micro-organisms are unable to penetrate the surface and runs off it.

The water repellency behaviour is best demonstrated by the typical beading of water droplets on the substrates . As shown in Figure 2 better water repellency behaviour is observed when the angle between the drop and the substrate is wider.

 

Three water repellent materials are available at Azmeh Company:

1-Protect 2000: based on silicone resin.

2-Protect 2000S: based on acrylic emulsion.

3-Protect2000R: based on siloxane emulsion.

The main features of these products are listed in the following table:

Protect 2000R

Protect 2000

Protect 2000S

Does not affect substrate porosity

Does not affect substrate porosity

 Small effect on substrate porosity

Excellent diffusion of water vapour and carbon dioxide from the substrate.

Excellent diffusion of water vapour and carbon dioxide from the substrate.

Good diffusion of water vapour and carbon dioxide from the substrate.

Very good beading effect “water repellency”.

Excellent beading effect “water repellency”.

Good beading effect “water repellency”.

Excellent freeze-thaw resistance.

Excellent freeze-thaw resistance.

Good freeze-thaw resistance.

Water based material. No harmful vapors and scents are present.

Fast drying solvent based water repellent material, the beading effect is noticeable within 5 hours of application.

Water based material. No harmful vapors and scents are present.

 

Characteristics and application process :

  1. These materials are intended only for vertical or steeply sloping substrates.
  2. Water repellent products are recommended to be applied to absorbent, porous, mineral building materials such as concrete, aerated concrete, cement, brickwork, sand lime brickwork, mineral-based natural and artificial stone, and mineral paint.
  3. Application should be performed in good weather conditions. Prevent application under direct sunlight or rain. Wait at least 24 hours after rain or water cleaning.
  4. The substrate must be dry and free of contamination such as oil, grease, laitance, and loose materials. Brush off any loose material. Sanding can also be used to remove any dirty surfaces. Water jet is then used as the end step of substrate cleaning.

    Note: Avoid the use of acidic or alkaline chemical detergents and cationic surfactants. If detergents are used for cleaning, it is necessary to rinse well the cleaned surface by water in order to remove any detergent residue.

  5. If application will occur on lime stone (the most widely used) it is recommended to apply Protect2000R, or apply Protect2000S   as sealer (first coat) then Protect2000 (After complete drying of Protect2000S).
  6. It is essential to carry out a prior test in a small area of the surface to be treated. The test provides the amount of material required for a substrate and the effectiveness of application. In general, and depending on surface porosity, surface saturation should be performed. Application of two coats wet on wet is in general sufficient to obtain good water repellency.
  7. Water repellent products may be brushed, dipped or spray applied.
  8. Do not use detergents for cleaning protected surfaces, washing occurs only by water.
  9. Overcoating is not recommended and is only possible if the next coat to be applied is a water-repellent paint.
  10. Be sure that coated surfaces by water repellent products are not exposed to water and rain for at least 5 hours.