UV PROTECTION FOR WATERPROOFING

Most of us are aware of the dangers of Ultra Violet rays on our skin. We protect ourselves as much as possible with clothing and protective sun blocking creams or simply avoid excessive exposure to the sun’s rays as much as possible.

But what of our buildings and especially our waterproofing products?

A French team of scientists conducted a 10-year climatology study using ultraviolet radiation measuring instruments based at Cape Town international airport. The results showed very high UV radiation exposure, especially during the austral summer, often reaching the “extreme” category (more than 11) on the World Health Organisation UV index.
South Africa experiences particularly high levels of surface and tropospheric ozone, especially in July and August, largely due to biomass burning activities.
UV attacks on buildings involve ultraviolet radiation from the sun degrading building materials over time, causing color fading, discoloration, reduced tensile strength, cracking, and delamination. This photo-degradation is caused by the breaking down of chemical bonds within materials like paint, plastics, wood, plaster, brickwork and concrete. Damage levels vary by location, building orientation (north and west-facing sides are more exposed), and the specific material’s UV resistance.

The direct effects of this process include the loss of impact strength, changes in color, cracking, loss of elongation, tensile strength, or chalking of the surface.
UV has a very serious impact on our waterproofing materials. Acrylics and most paints usually require refreshing of the coatings every 2-3 years. The surface starts to delaminate and “blister’ allowing UV to further attack the underlying substrate which invariably ends up in cracking or in degradation of the material. Cementitious waterproofing products are similarly
affected by UV and need some form of protection to prevent cracking. Polyurethane waterproofing products may “chalk” or yellow if not covered by an aliphatic UV stable and UV resistant top coat.

Bitumen products also need protection from UV rays and this is usually provided by Bitumen Aluminium paint. This not only reflects the sun’s rays providing cover to the underlying Bitumen but also lowers the heat absorbed by the building structure. Some individuals attempt to coat the Bitumen with acrylic paint but this soon de-bonds from the surface due to both UV attack and the “leeching” of chemicals from the bitumen membrane. This “leeching” is often under-estimated by contractors. Manufacturers of Bitumen Aluminium paint stress the fact that Bitumen Aluminium paint should not be applied to Bitumen membranes within 7 days of application. This is to allow chemicals in the bitumen to settle. If ignored this will often lead to “bronzing” of the paint and even “crocodiling” of the paint surface.

UV is most damaging to horizontal surfaces. Vertical surfaces have the ability to deflect UV rays whilst horizontal surfaces absorb them leading to eventual damage to the surface.

Do your waterproofing a favour. Provide it with a suitable sun block!

You may Contact our team For Any Questions

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