Preserving the Beauty of External Building Façade - The Proactive Approach

Ravi Shankar Singh, National Sales Manager, Remmers India Pvt. Ltd., Gurgaon

Façade - The reflection of a building's personality

The façade is known as the face of a building. It also reflects the profile of the occupants. Façade certainly has the major share in the appearance and impact of a building. Commonly used options are brick, natural stone, concrete, gritwash, exterior paints, and wood, glass and aluminum composites. They need to be cared for and protected against the weathering effect of the environment. Rather we need to anticipate the weathering environment in different parts of the world and provide a preventive treatment to the façade surface so that its functionality and aesthetics can be sustained for years.

The common problems that we see as the resultant of the environment are given in the tabular form and discussed in detail:

Façade	Common problems
Brick	Salt patches, green growth, water absorption, color fading
Stone	Water absorption, green growth, yellowing, shade variation
Concrete surface	Salt formation, sand depletion, water absorption, carbonation
Wood	Termites & insects, Moisture, Discoloration,  moisture ingress, staining etc

Exposed Brick facade

We have many buildings across the world with exposed brick façade and have unique identity. When it is subjected to rain and vehicular fumes, it tends to generate salt on the surface of the red brick which not only gives a patchy look but also indicates the signs of deterioration. Brick tends to open the capillary pores resulting in the ingress of water and water then travels to interior of the building spoiling the interior décor as well. Exposed brick façade would require treatment at the time of installation.

The recommended treatment for the various problems is written in tabular form:

A list of solutions which takes the common problems associated with Brick Façade
Salt formation	Salt inhibitor chemical penetrates the pores and capillaries of the brick and does not allow the salts to appear on the surface
Moisture ingress	Hydrophobic impregnation stops the water to penetrate inside the surface and repel both water and dust.
Green Growth	Bactericide, fungicide and algaecide (BFA) impregnation  for restricting the organic growth on the surface
Discoloration	U V resistant impregnation minimizes the natural process of discoloration

The treatment can be done on old surface also but cleaning has to be done with either Clinker Cleaner or Cleaning Paste, sometimes hydro jetting is required for effective cleaning before application of BFA and hydrophobic treatment.

Stone/stone cladded façade

Stone is one of the most durable materials being used for ages but some of the stone is porous and absorbs water and impurities from the environment, resulting in yellowing of stone, organic growth and de-bonding in case of cladding. Sandstone is prone to water absorption and it must be treated for the hydrophobicity, Bactericide, Fungicide and Algacide impregnation. Some of the impregnation material is solvent based and it tends to change the natural color of the stone so need to test the sample before application on entire area. Water based product is more suitable for stone which shows the change of color and there is moisture already trapped in the stone.

Concrete facade

Modern construction uses concrete extensively as the final finish. Concrete provides one of the highest life in terms of the durability. Concrete surface which is highly alkaline protects the structure from the weathering environment like fumes, acid rain, water ingress, organic growth etc… The pH of the concrete is 12.5. The concrete goes through a process of carbonation, Carbon dioxide, which is present in air in proportions of around 0.3% attacks calcium bearing phases converting calcium hydroxide to calcium carbonate

Ca (OH)₂ + CO₂—> CaCO₂ + H₂O

Resulting in drop of pH from 12.5 to 8.5. Once pH drops to 8.5 the process of concrete deterioration is faster and results in the weakening of structure. Hence cost to life cycle is higher and it needs protective treatment and life can be increased further, hence by bringing the life cycle cost further. 100% pure Acrylic coatings are used to protect concrete. According to the external environment the thickness will vary from 120 microns to 300 microns. The life of concrete can be further increased by 10yrs. Concrete Acrylic or Anticarbonation coating is very useful in coastal and high rainfall area.

Wood façade

Wood is one of the most beautiful natural products used in the making of house and on heights, it has been used in the exterior as well. In exterior condition, wood is exposed to the following six problems:

• UV rays
• Rain/moisture
• Termites/insects
• Mould/Algae
• Fungus
• Blue stain

Instead of treating product wood with different products, it can be treated with one impregnation material called HK Stain which shall take care of all the above stated problems. In order to improve the aesthetic and protection capability, another product called LT Stain and PUR Aqua Top 1K can be applied.

Conclusion

Whatever material we choose to install as our external face of the building would require a protection treatment to handle the extreme condition like water ingress, UV rays, pollution, insects, organic growth and chemical attack. In many cases, it has been observed that we do the treatment when we face the problem, but it is advisable to anticipate and do the treatment in the beginning itself to avoid the cost of repair, cleaning which will come as extra cost.