Cladding Fasteners : Are we being screwed?

Despite having reasonable National Building Regulations, an abundance of National Standards and an admirable Consumer Protection Act we constantly receive complaints from aggrieved parties about the poor performance of products supplied into the cladding market. In previous articles, we have highlighted the need to use SANS National Standards as a means of ensuring quality as well as the risks associated with accepting substitutions of products specified by competent professionals. Warranties can be substantially compromised if non-compliant components are used.

Since the opening of our market post-1994 we have had access to the best products the world has to offer, regrettably, the converse occurred. The market has become awash with inferior foreign products, sold at best by gullible vendors but mainly by rogues with price and a quick profit being the drivers. Suitability for purpose and durability are rarely considered. The vast majority of these products do not comply with either the National Building Regulations, SANS National Standards or other internationally recognized standards.

Fortunately, there are a few reputable suppliers that do supply quality and compliant products.

A fact that is not generally appreciated by specifiers, quantity surveyors and project managers is that there is no longer a local manufacturer of self-drilling roofing fasteners, only a limited range of self-tapping fasteners are manufactured locally. A disturbing trend which has become prevalent in this market is the misleading and often fraudulent claims made by vendors. Products are claimed to have withstood hundreds of hours of salt spray testing or are type class-3 or 4 etc. yet when tested locally fail to meet the applicable test criteria. Some even boldly claim their products comply with recognized standards and when challenged produce certificates issued by questionable or spurious bodies.

Whilst the subject of the validity of the various performance tests will form the basis of a future article we wish to explain briefly the background to the classification of coatings on fasteners and washers. Metals and metallic coatings are vulnerable to atmospheric corrosion in the presence of moisture. The extent of corrosion is dependent on the concentration of pollutants and amount of moisture. The International Organization for Standardization (ISO) developed a series of standards addressing the corrosivity of atmospheres which were divided into the six categories as detailed below.

CATEGORY CORROSIVITY
C1 Very low
C2 Low
C3 Medium
C4 High
C5 Very high
CX Extreme

 

The classes for the protective coatings on fasteners as defined in SANS 1273 and numerous other internationally recognized standards match directly with these ISO categories i.e. a class 3 fastener is required in a category C3 atmosphere. Revisions to SANS 1273 will also include washers.

Another area of concern is the weatherproofing gaskets on flanged head fasteners and bonded washers. These can be anything from sealed sponge rubber through various plastics to EVA and EPDM. Gaskets need to be capable of operating at temperatures between -10° to +80°C, be UV resistant and be free of active carbon. No sponge based products and the majority of plastic gaskets meet these criteria. Their early failure leads to premature failure of the fastener and accelerated corrosion of the cladding. Based on historical performance EPDM has proved to be the superior product with a service life in excess of thirty years.

SANS 10400 Part-B and the soon to be released revised SANS 10400 Part-L stipulates a minimum design working life for cladding (including fasteners and ancillary items) of fifteen years. In addition, Part-L requires any roof covering component to during its design working life resist amongst other things;

  1. Effects of UV radiation without deterioration of its essential properties.
  2. Chemical attack from common atmospheric gases and saline atmospheres.
  3. Accumulation of hail after moderate hail storms shall not cause water to penetrate the interior of the building.

 

It is mandatory to comply with the National Building Regulations of which the various parts of SANS 10400 constitute the minimum deemed to satisfy requirements. It is therefore of paramount importance when specifying or evaluating cladding systems to ensure compliance with SANS 10400 together with the manufacturer’s conditions of warranty.

One fail safe method to achieve this is to insist on products complying, preferably, with SANS standards, failing which other internationally recognized standards. Test results of compliance with such standards should be from a SANAS (SA National Accreditation System) accredited organizations.

For other related articles please visit our website www.samcra.co.za