Tuesday, 28 March 2017 14:16

Safintra Cape Town boasts two dedicated Saflok concealed fix mills

In large-span metal roofing applications, concealed fix roof systems are the only choice.

In these applications, with the size of investment concerned, engineering performance of the entire roof “system” is critical.

In Concealed fix systems, sheets are fixed to the purlin with a clip system, and are not pierced with any fasteners. The clips serve two purposes – they circumvent the need for holes in the sheet (which prevents the possibility of leakage through the perforation) and they allow the roof to expand and contract in a sliding movement over the clips.

Because the sheets can slide over the clips, they can be rolled in long lengths which can thermally expand without restriction. If the sheets were positively fastened through the sheet into the purlin, the fasteners would take the brunt of the force of expansion, and would tear larger holes in the sheet, or shear off. Consider that coated steel expands at a nominal 1mm per 1m, and it is apparent that a sheet of a mere 15 m will move by 15mm in heat. It is common best practice to not install a pierced fix sheet in lengths of more than 15m for this reason. Over 15m, a pierced fix sheet should be end lapped to allow for thermal cycling.

A concealed fix system allows sheets to be rolled in continuous lengths up to 120m or more. The lack of end laps further helps reduce the risk of leaks.


The first distinguishing characteristic of a concealed fix roof is the profile, which is both aesthetic and functional. Of equal concern is the design of the clip, as this is the “anchor” securing the sheet to the sub structure and holding it down in high winds. The overall “system” design defines the manner in which the clip locks into the sheet profile. Bear in mind that the system must also be able to withstand the foot traffic and loads imposed by the installation of HVAC units, rooftop photovoltaic (PV) systems, or other utilities.

As a professional, you should demand full technical details of the system you intend to specify – and request technical support throughout the installation itself.

Safintra is proud to offer this service free of charge to all its customers from 7 branches countrywide.

Saflok™ 410 with the 410mm effective profile and the Saflok 700 profile are now both dedicated in the Cape region.

 

Call our branch on: +27 11 981 3130 or visit our website on www.safintra.co.za