Tophat Purlins

Central Steel Framing’s Tophat Purlins are a versatile, lightweight, economical and an easy-to-use product for roof purlins, wall girts, floor joists, carports, fencing and many other applications.

Ideally for spans from 3m to 7m, Tophat Purlins will provide an economical alternative to standard timber beams or steel C purlins.

Tophat Purlins are easy to work with – they are fastened directly to their supports which results in a saving on cleats. The symmetrical section means no braces or nogs are needed to prevent twisting, and the profile is easily lapped for optimal performance.

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  • THF Flashing Plates: Flashing Plates are used where Tophats pass through the cladding to support a canopy. They prevent pests from passing through the gap that would usually be left in the cladding.
  • Jamb Flashings: Jamb Flashings are used where a door or window is cut into the side of a building to flash off the cladding and Tophat girt.
  • Batten Hanger Brackets: Designed to work in with 100mm and 120mm Tophats, where a shed needs to be lined and you require a 150mm ceiling cavity.


Tophat Purlins are manufactured from hot dipped galvanised steel with a coating weight of 275gram/sqm, in line with other common lightweight steel structural building products.

This gives good protection in most exposed internal environments, and for external use in moderate marine environments. Where used in a lined interior dwelling, a thermal break should be installed between the Tophat and the cladding to avoid thermal bridging. 

Handling and Storage

Tophat Purlins must be kept dry during storage as water present between close stacked sections will cause premature corrosion. If they become wet, they should be separated and stacked openly to allow for ventilation to dry the surface. 

Where sections are exposed to salt spray but not rain washing, maintenance is required to remove any build-up of salt deposits on the surface.

Run off from, or contact with, materials which are incompatible with zinc should be avoided.


Tophat Purlins are available in long run lengths up to 12 metres, depending on the available transport and handling facilities. 


Cutting onsite is preferably done by tin snips, hacksaw, or cold cut saw. When using abrasive disc blades care must be taken to ensure the swarf produced does not affect other materials and the burred edge should be cleaned off at the completion of cutting, followed by a coat of zinc-rich cold galvanised spray.