Clay and concrete roof tiles are still viable roofing options for modern architecture in South Africa.
The clay roof tile is one of the oldest roofing materials invented by men to protect buildings from the elements – one that stood the test of time and still exists today.
This is according to Isaac Simelane, architectural and specification manager at Marley South Africa, who points out that a properly built and maintained clay roof can last over 100 years.
Advanced and refined
Yet, according to Simelane, clay roof tiles produced today are very different from what they were 50 years ago, both technically and aesthetically. “Over the last two decades we have seen a huge technical leap in terms of production methods. The new clay composition produces tiles that are more resistant and long-lasting. Water absorption was reduced significantly to values as low as 3%, which means that they can be used under the most severe conditions without the risk of losing their technical capacity,” he explains.
“In addition, many new accessories, colours and finishes have been developed, allowing versatile designs in virtually any shape and form imaginable,” he says.
More than just one look
Willem Grové, marketing manager at Monier Coverland, highlights that since the traditional, standard double-roman profile tile makes up the bulk of the market for concrete tiles, it is easy to forget about other profiles available. “One can really make a building stand out by just opting for a different tile profile. We are seeing concrete tiles used on mono-pitched roofs and flat tiles are especially trendy at the moment to achieve a modern look,” he states.
The added option of pre-coated tiles also gives a deeper, richer colour on the roof than traditional roof tiles that are a bit softer in colour. “And while colours may weather and fade over time, since the body colour of the tiles is the same as the surface colour, weathering happens in a uniform way,” Grové says.
A neat finish
According to Grové, to prevent damage to the ridge line of a roof, which can sometimes crack and result in leaks, a dry-ridging technique that has been used for tiled roofs in Europe for many years is now gaining ground in South Africa.
“The ventilating ridge system involves a sealing compound that is simply rolled and stuck over a ridge baton and onto the tiles at the ridge line. The ridge tiles are then secured to this baton. The result is a clean-looking ridge line which is protected against leaks, wind and dust, providing a long-term benefit,” Grové explains. Although the initial setup costs of mortar application may be low, it’s short life-span, particularly in harsh weather conditions, urges homeowners to explore more innovative, sustainable ridge and hip-line solutions.
Suited for diverse climates
Concrete tiles are strong and hardy. Independent hail impact tests conducted by the SANS have indicated that a hailstone diameter of between 40-50mm and larger is necessary to damage standard Coverland concrete roof tiles, according to Grové. “In the event of an extraordinarily large hail storm, it is much easier to fix one or two tiles than replacing larger roofing sheets,” he states.
The ability of a hailstone to cause damage is directly proportional to its energy on impact and this in turn increases with the diameter of the hailstone. In brief a large hailstone is potentially a greater hazard than a small hailstone. The majority of hailstones studied have a density of 910 kg/m3 indicating virtually clear ice. The shapes of hailstones are varied and although these have a limited effect on the damage potential it is negligible compared with the overall effect of the hailstone diameter, i.e. terminal velocity versus impact energy.
Other conditions listed by Simelane, which can be very harsh on a roof, are coastal areas with high salinity, frost and severe wind. “In the vastness of the South African territory one is bound to find the most different conditions, which will condition the choice of a roofing solution and clay roofing that is suitable for all weather and environmental conditions that one may find,” he says.
“Although the purchasing price may be slightly higher than other roofing options, the maintenance cost is almost irrelevant and when considering that this solution can last a lifetime, it becomes by far the cheapest roofing solution available.”
Simelane further points out that clay roof tiles have one of the lowest environmental footprints when comparing roofing solutions. “In terms of production, clay exists naturally and doesn’t require much processing. On the other hand, because of its durability, the amount of waste produced due to roof replacements is insignificant,” he states.
“A ventilated clay tile roof allows energy savings as well. Concerning roofing materials, clay is one of the lowest conductors of temperature, and by allowing the air to circulate beneath the tiles a natural thermal insulation is achieved. This reduces the cost on roof insulation materials and creates a more stable temperature indoors without the need of artificial cooling or heating systems.
“Being one of the most ancient products still in use, clay roof tiles are one of the most high-tech and efficient ways to protect buildings over their lifetime,” Simelane concludes.
Full thanks and acknowledgement go to Marley Roofing and Monier Coverland for the information given to write the article.