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41489 BSA

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June 2024


SFS facilitates faster fixing of tapered insulation over steel decks with BSA system launch

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The SFS BSA fastening System

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Martyn Holloway, Flat Roofing Business Development Manager at SFS

Ongoing investment in research and development bySFS Group Fastening Technology Ltdhas brought the launch of the construction industry's first ever adjustable fastening system for use with tapered - AKA cut-to-falls - insulation, installed over steel decking.

TheSFS BSA adjustable fastening systemfollows on from the success the manufacturer has enjoyed with its TIA product, introduced a decade ago for use on concrete roof decks. Importantly, it offers roofing contractors a faster, simpler, and more cost-effective solution for securing insulation or single-ply membranes across multiple insulation layers up to 500mm thick. 

There are three primary components to the patented system - the choice of a 110mm or 160mm fastener; thermally-broken polyamide sleeves available in lengths from 70-330mm; and five different stress plates which clip onto the sleeves for membrane or insulation securement.

The BSA fastener features two different thread zones separated by a thread-free zone.  To install, the efficient drill point cuts through the steel deck while the lower thread is designed to threadform and also restrict penetration through the crowns of the deck to a maximum 20mm.  

The specialist drive bar tool then engages with the locking nut, held captive in the sleeve, to effectively tighten the assembly down into position. Then if the roof is trafficked the nut is free to move within the sleeve, before returning to its original position when the load is removed; this telescopic arrangement making BSA a very safe option for use with PIR and stone wool insulation. 

For membrane installation when using BSA with tapered insulation, there is a choice of either the traditional isotak seam (or lap fixing) system or field fixing using the isoweld induction welding system.  Using isoweld, single ply membrane is welded to dedicated stress plates.  No fixings penetrate the waterproofing as a result.  Rather than seam fixing, induction welding uses a field fixing arrangement where the stress plates are installed in a grid pattern.  The Isoweld fasteners provide for both insulation and membrane retention and are evenly distributed, independent of the membrane seams and the result is increased efficiency, security and cost saving opportunities.

The BSA adjustable fastening system is CE-marked, fully tested and carries ETA Approval, while it has been successfully trialled on projects in the UK and Germany, receiving excellent feedback from contractors.

Martyn Holloway, Business Development Manager, Flat Roofing for SFS, comments:

"The use of adjustable fasteners for installing tapered insulation and single ply membranes on flat roofs removes complexity and simplifies the install. The BSA system offers up to 85mm adjustability using the same fastener and sleeve combination so this means that with a1:60 fall the same combinations can be used for four separate boards, whilst achieving a consistent 20mm fastener penetration through the deck. 

"By contrast, using standard fasteners significantly more components and rationalisation of fastener lengths will result in varying penetration depths ranging from 20 to 70mm.  A consistent 20mm penetration across the complete roof significantly cuts the risk of damaging M&E services below the deck.

"Compared with adhesive fastening of tapered insulation schemes, the BSA adjustable fastening system will provide for a significantly faster and more cost-effective solution. One fastener will fix through multilayers of insulation and without the need for priming the deck nor expensive bitumen-based Air and Vapour Control Layers. Additionally, mechanically fastening is less weather dependant, especially in terms of temperature".     

SFS is pleased to offer project specific technical guidance and specification support, including wind load calculations and site pull-out testing to assist determine the correct number of fixings for either field or seam fixing methods of single ply membrane installation - or alternatively for insulation attachment, for example, where liquid applied membrane systems are specified. 

For further information, call0330 0555888or visit


With Compliments:

Taylor Alden
7 Bell Yard




SFS Group Fastening Technology's Construction Division is the world's largest manufacturer and distributor of carbon and stainless-steel fastening solutions for roofing, cladding and façade systems.Additionally, SFS manufactures an award-winning fall protection range, innovative rainscreen subframe systems and high-quality hinges for windows and doors. The reputation of this established company, which has been in the UK for over 120 years, rests on value added propositions along with company-wide technical expertise.Today, the company does not solely create products to fix, fasten and protect buildings; the proprietary "Securing Futures" mission ensures that investments and people are better protected too.


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