SAISC TECHNICAL
Cladding :
Back to Basics
by BSi Steel
If one discusses cladding , I am quite certain that it would be up to individual interpretation what that actually means . Some may interpret it as flashings , some a material coating , some actual material with a coating . I have tried to cover all interpretations and kept the following information as simple and precise as possible to provide some insight into the meaning of “ cladding .” In essence cladding is the waterproof envelope of a building .
In the case of roofing it would either be a pierced fix or concealed fix profile produced a steel coated material in the desired profile ( Corrugated , IBR , Widespan and / or a number of patented concealed fix designs ).
The steel base material is most commonly protected by a galvanized ( Z ) or Aluminium- Zinc Coating ( AZ ) both of which offer different types of protection .
Galvanized coating The mild steel is continuously hot-dipped into an almost pure zinc formula to cover the material and this provides a sacrificial layer in the form of a shiny zinc coating , which can be supplied in various spangles to create a different surface appearance . As zinc has a corrosion rate one tenth that of steel a Z275 coating will protect the mild steel substrate for between 10 and 15 years , depending on environment .
Aluminum zinc coating The mild steel is continuously hot-dipped in a formulation of aluminum , zinc and silicon . The addition of aluminum increases the protection factor by almost 4 times in a marine environment thereby providing a tougher barrier between the mild steel substrate and the elements .
The above materials are available with an organic coating , in a range of colours , under various copyrighted names e . g . in the coated and painted mild steel substrates in the form of Chromadek ( Mittal produced ) and Colorplus ( Safal produced ). These coatings in addition to being aesthetically pleasing provide an additional barrier to corrosion .
Flashings The generic term for a number of specially formed designs which in broad terms are roofing components to seal the transition of areas of cladding ( valleys , hips , ridges , barge , etc .) or where cladding joins masonry or decorative trim .
These flashings are produced from the above materials to ensure compliance and compatibility with the cladding materials to ensure the roof sheeting flows in design . It is advisable not to mix colour coated materials from different suppliers as each paint system has unique weathering characteristics .
Bullnosing and curving of roofing sheets is a process that is applied after the production of the profiled roof sheets and is a process rather than additional component as is the case in in Flashings .
BSi Steel ( Pty ) Ltd Roofing , is located at Kliprivier ( Meyerton R59 ) and produce an IBR , Corrugated and Widespan Profiles in the mentioned materials . Bullnosing , curving and flashings are supplied to your specification .
7 Steel Construction Vol . 40 No . 3 2016 Steel Construction Vol . 40 No . 4 2016 7