Make The Right Choice On Site

Make The Right Choice On Site

By Gareth Griffiths

“Goedkoop is duurkoop” The original pre-painted galvanized roofing on this upmarket Cape Town home (seen on the right) needed complete replacement after less than 10 years in service and was replaced progressively by the contractor from the left using by Clean COLORBOND steel.

In this advisory article, a well-known steel roofing material supplier points out that both what happens on site needs to be monitored to ensure the right grade of steel as specified is actually used.

There is an old South African saying ‘goedkoop is duurkoop’. As a company worldwide, we have found that substituting a high quality roofing material such as ZINCALUME® steel or a high quality pre-painted steel such as COLORBOND® steel with an alternative material is sometimes done in error at the last minute to reduce building costs, without the specifying team being aware of it. We strongly advise against this practice” says Arno Hanekom, Regional Manager Africa, for steel roofing multinational company, BlueScope.

Following the old adage that form follows function, it is also true that the selection of materials used should mirror the intended function of the building, including elements of sustainability such as long life.

Sustainability starts with the roof”, says Hanekom. “By this, we mean that what covers the building is crucial to life and operating performance of the structure; and also that the right material needs to be specified during the design phase of the that building”.

But what happens on the building site is of critical importance. Misguided decisions by project managers, contractors and even built environment professionals can result in substitution of high performance steel as specified by architects with cheaper low grade options. These affect both performance and service life negatively” he says.

Look for the branding on the reverse side of the product

According to Hanekom, quality steels such as the ZINCALUME and COLORBOND steel brands have a dot matrix branding on the reverse side which clearly distinguishes the product concerned. This makes it easy to spot during construction site inspections.

He warns that substitution with cheaper grades of steel roofing often leads to two things happening:

  1. Corrosion and breakdown of the metal substrate at an accelerated rate compared with the BlueScope product. The company’s steel brands have been found to deliver a service life of more than four times longer than conventional galvanised or pre-painted galvanized steels, even where the substituted product contains a higher base metal thickness of steel.
  2. Colour and thermal performance. Premature fading and loss of infra-red reflectance are two key areas steel roofing of today. “There is no substitute for the performance of our ZINCALUME and COLORBOND steels when it comes to both the appearance of and a cooler roof”, adds Hanekom.

Reputation on the line

Hanekom asks: “Look for the brand that identifies the long lasting guaranteed performance of genuine ZINCALUME steel and COLORBOND steel from BlueScope. Why risk your reputation when you can enjoy peace of mind by using genuine ZINCALUME steel or Clean COLORBOND steel?”

Proof is in the testing

The pictured samples were exposed at BlueScope’s Bellambi Point Australian test site for the same period of time under a severe environment. The galvanized steel (left) shows a severe loss of zinc coating and consequent red rusting of the steel substrate, while the ZINCALUME steel sample (right) is still in good condition.

… and in real life
BlueScope’s local South African office has a number of case histories where COLORBOND steel was used to completely replace pre-painted galvanised roofing that had severely corroded after just 3 years. Now, 10 years on, those COLORBOND steel roofs are still intact.