SAISC SUBSIDIARIES : SAMCRA
By Dennis White , Director SAMCRA
Technical journals , manufacturers ’ data sheets and brochures regularly make reference to these three titles and often mix them in a single sentence which has resulted in a certain amount of confusion and begs the question – what is the difference ?
When metal cladding was first introduced into Europe it was in the form of flat sheets which formed a weatherproof cover over a timber sub-structure ( supported cladding ). The side and end laps of individual sheets were folded over on themselves and then flattened to form a weatherproof seal as seen on metal clad domes etc . Over time it was found that if the longitudinal seams were left upright and the depth of upstands seam profiles produced regionally by a number of specialist contractors plus two self-supporting profiles sold nationally . In essence a standing seam profile comprises a broad pan with narrow upright mechanically seamed side laps that encapsulate an anchor cleat or halter .
In the broad sense concealed-fix ( ed ) or secret-fix ( ed ) cladding is any type of cladding where the means of anchoring the cladding to the supporting structure are not visible from the outside . Profiles range from a conventional pierced-fix box rib profile with a clip-on cover strip that conceals the heads of the fasteners , direct fixing through a concealed flange , a spring
In the broad sense concealed-fix ( ed ) or secret-fix ( ed ) cladding is any type of cladding where the means of anchoring the cladding to the supporting structure are not visible from the outside . Profiles range from a conventional pierced-fix box rib profile with a clip-on cover strip that conceals the heads of the fasteners , direct fixing through a concealed flange , a spring action clip through to an encapsulated clip-over cleat or halter .
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. samcra . co . za increased , it was possible to double fold the top half of the upstands over on themselves and thereby achieving a more effective weatherproof seal and control of rainwater runoff . Hence the name standing seam . With the transition from supported to self-supporting cladding , corrugations were introduced to provide the structural properties of the cladding . Following the development of the continuous rolling process , trapezoidal ribs were introduced which resulted in stronger and more efficient profiles . The side laps in all modern cladding profiles are technically standing seams .
There are numerous manufacturers in Europe and North America producing traditional standing seam profiles i . e . single pan with narrow upright longitudinal seams , most of which are mechanically seamed . In South Africa there are supported standing action clip through to an encapsulated clipover cleat or halter .
In essence , except for some minor variations , it is a case of ‘ a rose by any other name …’
The current everyday understanding of these titles is : 1 . Concealed-fix or secret-fix is any profile where the anchoring system is not visible , which provides unrestrained thermal expansion or contraction and does not require any form of mechanical seaming .
2 . Standing seam is any profile where the anchoring system is not visible , which may or may not provide unrestrained thermal expansion or contraction and does require mechanical seaming . 3 . On an historical point Secret Fix was a patented system marketed by H . H . Robertson ( Africa ) ( Pty ) Ltd circa 1980 which comprised a pierced-fix deep box rib profile with a clip-on cover strip that concealed the heads of the fasteners .
28 Steel Construction Vol . 40 No . 1 2016