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Sarnafast Mechanically Fastened Roofing
The Sarnafast system typically consists of:
- A structural deck
- Loose laid vapour control layer
- Mechanically fastened thermal insulation
- Mechanically fastened Sarnafil S327-EL or Sarnafil TS77-E membrane
The Sarnafast system is not suitable for applications without thermal insulation.
The vapour control layer is generally a polyethylene, such as EcoVap or Sarnavap, with all overlapping joints sealed with Sarnavap tape. If a bituminous vapour control layer is used, it must be fully adhered to the substrate with Sarnacol 2142s, synthetic cold bitumen or hot bitumen (if insurance permits the use of this method).
A thermal insulation board, meeting the requirements of BS 6229 : 1982 ‘Code of Practice for flat roofs with continuously supported coverings’, such as SarnaTherm, will be mechanically fastened through the vapour control layer to the substrate, using SBT tubes and SBF fasteners with a SBIW-70x70 pressure plate.
Finally, the membrane is loose laid and one side of the membrane is mechanically fastened with SFT tubes and SBF fasteners, using a TP installation tool along the line marked on the sheet, 30mm from the rear edge. The fixing centres required, are calculated by Sarnafil Ltd to meet the wind uplift requirements of the project. The following roll of membrane is unrolled over the first sheet by 120mm and the resulting overlap hot air welded with a Sarnamatic automatic welder. At all perimeters and penetrations, the membrane is mechanically fastened with Sarnabars or SFT tubes.
Notes:
- In a roof refurbishment, the existing waterproofing system can often be used as the vapour control layer.
- If Sarnafil S327-EL membrane is to be installed over an unfaced extruded or expanded polystyrene thermal insulation board, a separation layer of Sarnafil Glassmat 120 should be used.
- End overlaps and the ends of the Sarnamatic welds are finished by hand welding.
© 2006 Sarnafil Ltd. Legal Disclaimer
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