Window & Door Specifier V - SFS intec
Vol.2 No.2 / A magazine to help specifiers make the right choices
Window & Door Specifier
Demanding a watertight guarantee
All the signs are that specifiers are tightening their grip when it comes to components for windows and doors. The message has hit home that to combat the risks of corrosion and subsequent window failure, only austenitic stainless steel fasteners offer guaranteed performance. Whilst some sectors of the fastener industry continue to seek alternatives to the proven austenitic solution, none has
been able to demonstrate corrosion free performance of non-austenitic screws over 10 years in real life tests. Until they do specifiers will increasingly choose austenitic fasteners. Currently, 90% of specifiers who include fasteners in their specification already do so.
Mike Mortell
Withstanding the test of time The faultless performance of austenitic fasteners in the recent test programme is reinforced by more exhaustive tests carried out by the respected Swedish Corrosion Institute. Its report (R62 124: 1995) provides details of real life testing over 10 years of different materials used in construction. Testing in rural, urban and coastal environments, the study concludes that only austenitic stainless steel (300 series) offers guaranteed anti corrosion performance in all environments. Coated carbon steel fails across the board whilst martensitic steel (400 series) fails in urban and coastal locations.
2
The f
Corrosion on modified martensitic fasteners. Recent analysis confirms the corrosion not to be tooling contamination, but highlights an inherent problem.
ear of random failure Subsequent tests by the European Otto Graf Institute confirm that the corrosion resulted not from tooling contamination but from an inherent problem in the manufacturing process. Modified martensitic fasteners rely for their corrosion resistance on their smooth surface finish. The Otto Graf Institute concluded that “the corrosion is attributable to the influence of chloride commonly found in urban/industrial environments. The susceptibility of the screws depends on their surface finish; the surface finish was very uneven and had fissured areas locally, resulting from the manufacturing process.” What is alarming for the specifier, is the inconsistency of the modified martensitic product. All ten samples in the UK tests were selected from the same box, therefore presumably the same production batch. At the start of the test it was impossible to identify which three would corrode. That kind of random failure is simply not acceptable for specifiers seeking guaranteed performance.
The results of tests into fastener performance confirm that the new modified martensitic fasteners - offered by some suppliers as an alternative to austenitic - fail to offer a consistent guarantee against corrosion. In some cases, modified martensitic screws shows clear signs of corrosion after just four weeks atmospheric exposure. The evidence first came to light in May, following tests carried out in the UK. Fasteners used to attach stainless steel hardware to reinforced and unreinforced PVCu windows were tested in isolation, Product 400ss to avoid contamination from other Sample external sources, and in 4.8x16 SD No. modified application. martensitic (A) The natural exposure programme was carried out in an urban 1 O environment over a 28 day period. 2 O Test samples, ten of each, were R/T UH 3 subjected to temperatures varying 4 O from 5˚C to 23˚C. There were R/T 5 periods of rain and dry spells and 6 O varying degrees of humidity. 7 O As expected, the 300 series R/T 8 austenitic fasteners showed no 9 O visible signs of corrosion at the 10 O completion of the tests. In contrast, the modified martensitic fasteners in application showed visible signs of red rust on the threads within two weeks and rust under the head after four. In isolation, three of the ten samples of the modified martensitic showed red rust on the threads.
Product 300ss other 4.8x16 ST all austenitic (B)
O O O O O O O O O O
Product 300ss other M4x18 SD austenitic with carbon steel drill point (C)
W/TH UH W/TH UH W/TH W/T UH W/TH UH
O O O W/TH UH W/T
Product 300ss SFS SP2S 4.2x16 SD all austenitic (D)
Product Product 300ss 300ss SFS SPS other M4x16 SD 4.2x22 SD austenitic austenitic with with carbon steel carbon steel drill point drill point (E) (F)
O O O O O O O O O O
O O O
W/A
W/H
W/A
W/A
W/A
W/T
W/A
O O
W/A
W/T
W/A
W/H
W/A
W/TH
W/A
W/A
KEY SD = Self drilling product for reinforced steel/ aluminium profile ST = Self tapping product for unreinforced profile O = No corrosion visible
R W T H UH A
= = = = = =
Red rust formation Oxidation of zinc Visible on the threads Visible on the head Visible under the head All over
3
Robin Szymura checks to ensure that window suppliers are complying with Salford’s strict austenitic fastener policy whilst Peter Dunbevand looks on.
Tightening the screw spec These days the City of Salford is becoming well known for the tightness of its window specification. With a wide mix of housing stock - 34000 dwellings in total - the Council’s Engineering & Architect Division is demanding a 30 year life of its windows. With a £5 million annual maintenance budget at their disposal, the Pre-Paint Repair team make policing their specification a major priority. Nowhere is that more in evidence than in their window fastener policy where their commitment to austenitic screws is total. High Rise Around 15% of Salford’s council housing stock is high rise, built in the 1960s and 1970s to meet the demand to replace, quickly, the dilapidated slums depicted so graphically by painter L.S. Lowry. A further 10% of Salford’s portfolio is in medium rise, the remainder in pre- and post-war traditional dwellings. Wholesale PVC Following two pilot schemes in the early 1980s at The Valley Estate, Salford took the decision to go for wholesale PVC-U window replacement in 1986, with a programme to replace all metal windows, and the predominantly softwood timber windows, in the 1960s and 1970s housing. By 1997 virtually all the pivot windows in the high rise blocks had been replaced with PVC. Specifications require triple chamber construction, minimum wall thickness for the profile and are stringent about the quality and performance of the hardware. Salford rejected both tilt and turn and pivot options for high rise, in favour of top hung reversibles fitted with opening restrictors for safety.
4
All two storey buildings are fitted with inwardly glazed casement windows. Originally the specification stipulated cockspur handles. For security, mushroom espagnolettes are now required. Austenitic Benefits Initially the specification allowed fabricators to use their own discretion in selecting the fasteners which affix the hardware. It was a seminar staged by fastener manufacturer SFS Stadler Ltd which first drew the team’s attention to the fact the material from which a screw was made could significantly affect the long term performance of a window. Made aware of the benefits of austenitic screws Salford changed its fastener specification to require that screw fasteners shall be manufactured from austenitic (non-magnetic) stainless steel as BS 311 Part 2 with the exception of those fasteners used for reinforcement retention only. The ‘non-magnetic’ reference serves as a sharp reminder to any supplier hoping to substitute inferior fasteners for the specified item. It lies at the heart of Salford’s policing policy. The threat that contractors who breach the austenitic specification will be required to replace unsuitable screws is sufficient to win compliance. That the spec may marginally increase the cost of each window does not perturb Salford. Having seen the problems caused by corroded screws they know that the most cost-effective window is the one that is made right first time. Doing it right saves money in the long term. Equally, a tight spec allows all quality fabricators to tender for contracts on a level playing field, using the same high grade window components.
Around 15% of Salford’s Council housing stock is high rise. Pictured (left to right) Project Architect Peter Dunbevand; David Holland, Team leader of Technical Services Department, Salford City Council and Robin Szymura, Specification Manager of SFS Stadler Ltd.
5
Building trust With around 90% of its residents aged 70 or over, Anchor Trust has a special obligation to provide quality support, care and housing. A recent tightening of its window specifications reflects the thoroughness of Anchor’s approach, right down to the very last screw.
From a building maintenance perspective, the challenges facing Anchor are slightly different from those faced by other associations. Almost all of Anchor’s dwellings have been constructed during the past 30 years, the vast majority in the 1970s, in two and three storey blocks. As was the vogue in the 1970s, most were fitted with softwood windows and cills; at the time there were no statutory requirements to provide ventilation. Largely, Anchor managed to adhere to its target of 4 - 5 years external repainting programmes but, as experienced by so many other housing associations and local authorities, that didn’t prevent the problem of rot. Virtually all of the windows were single glazed and the resultant condensation meant frames rotted from the inside. Solution It was in the early 1990s that Anchor adopted the PVCu solution, initially creating their own performance specification to select appropriate profile systems and subsequently drawing on the LHC’s established expertise in the specification of windows. The switch to PVCu frames also heralded the switch to double-glazing as standard too. In 1995/6 around 3500 new windows were fitted in Anchor flats across the UK; in 1996/7 a further 3000. Foresight Unlike many others who have viewed PVCu frames as the ‘maintenance-free’ option, Malcolm Gara and his colleagues were quick to realise that, despite the maintenance cost-savings and excellent thermal performance offered by PVCu frames, to work effectively they still need caring for too. It is Anchor’s foresight in tightening the specification for some window components even beyond the standards laid down by the LHC requirements, that will safeguard Anchor from problems which others may face in the next few years. It was at an industry seminar that Malcolm Gara, Head of Property, was first made aware of the potential risks of permitting the use of carbon steel
6
Anchor has been fitting PVCu windows to its properties since the early 1990s.
or martensitic steel fasteners to affix hardware to PVCu window frames. He was so concerned about the possible risk of window failure and the potential risk to tenants, that he arranged a special briefing session for the Trust’s 27 property surveyors. The result was an amendment to the specification and a reinspection programme of previous installations to identify and eradicate any problems. Traditionally windowmakers have preferred to affix window hardware using coated carbon steel or martensitic steel screws, but both materials are intrinsically corrosive.
There’s more to choosing a fastener than simply specifying the material from which it is made. With over 500 different types of fasteners available for affixing hardware and reinforcement to PVCu frames, windowmakers and specifiers need professional guidance to make the right choices. For UK fastener manufacturer SFS Stadler Ltd., that resulted in the creation of a technical assessment team. Qualified field sales engineers, headed by Technical Manager Nigel Wood, provide advice on the most effective fastener for individual applications taking account of the security, load bearing and weather performance requirements. For window systems companies the team produces systems specific manuals to guide their fabricators in fastener selection. If you require input from the team contact Nigel Wood on 0113 208 5500.
Eliminating Excuses Only 300 series austenitic stainless steel is suitable, and the introduction of a bi-metallic fastener, with a hardened steel drill point and an intrinsically non-corrosive shank and head, eliminates any excuse for windowmakers not to provide the corrosion-free option. Evidence suggests that unless specifiers write in to their specification a requirement for austenitic fasteners, ideally with a manufacturer-backed ten year warranty, windowmakers will continue to try to fit inferior and inherently corrosive alternatives. There have been a number of incidents of window casements falling out, with potential risk to life, because of failed screws. Anchor now specifies SFS Stadler austenitic fasteners for all window fixings other than the retention of reinforcement within the profile. SFS provides a written warranty against corrosion, a separate third party product liability insurance, and provides an advisory service to window contractors to Anchor on the appropriate screws for new windows and remedial work. This report is adapted from an article which first appeared in Housing Association Building & Maintenance magazine.
Helping the specifier make the right choices
Gary Hampshire (centre) of Leeds window fabricator Roseville Enterprises affixes hardware whilst SFS’ Nigel Wood (left) and Neil Ackroyd look on.
7
For specifiers in the private and public sectors, security remains a key issue. On French and residential doors the hinge has traditionally been a potentially weak point. Now, a new range of all steel hinges, fitted with a specially designed security device, enables doors from most profile systems to meet the security requirements laid down in PAS024, which is currently in draft form. The six hinge range offers both face fit and butt hinge options, allowing the hinge to be affixed into reinforcement if required. The range allows for varying degrees of adjustability, ensuring that the doors are easy to fit and will continue to give optimum performance for their lifetime. The strength and durability of the hinges results from their all steel frame and sash barrel construction. Whereas hinges from other material may shatter on hard body impact, the SFS range will not. It also performs exceptionally well in soft body impact tests.
SFS Stadler Ltd Idsall House High Street Prestbury Cheltenham GL52 3AX Tel: 01242 585400 Fax: 01242 520682 and 153 Kirkstall Road Leeds LS4 2AT Tel: 0113 208 5500 Fax: 0113 208 5539
8
The SFS Group is an international manufacturer of fastening solutions for the construction industry. With operations in the UK, Switzerland, France, Germany, Italy and the USA, the Group invests over £20 million per annum in product design, development and enhancements to manufacturing plant and equipment .
Designed and produced by The Partners Group, York. Tel: 01904 610077
Security hinges on steel
Window & Door Specifier
Demanding a watertight guarantee
All the signs are that specifiers are tightening their grip when it comes to components for windows and doors. The message has hit home that to combat the risks of corrosion and subsequent window failure, only austenitic stainless steel fasteners offer guaranteed performance. Whilst some sectors of the fastener industry continue to seek alternatives to the proven austenitic solution, none has
been able to demonstrate corrosion free performance of non-austenitic screws over 10 years in real life tests. Until they do specifiers will increasingly choose austenitic fasteners. Currently, 90% of specifiers who include fasteners in their specification already do so.
Mike Mortell
Withstanding the test of time The faultless performance of austenitic fasteners in the recent test programme is reinforced by more exhaustive tests carried out by the respected Swedish Corrosion Institute. Its report (R62 124: 1995) provides details of real life testing over 10 years of different materials used in construction. Testing in rural, urban and coastal environments, the study concludes that only austenitic stainless steel (300 series) offers guaranteed anti corrosion performance in all environments. Coated carbon steel fails across the board whilst martensitic steel (400 series) fails in urban and coastal locations.
2
The f
Corrosion on modified martensitic fasteners. Recent analysis confirms the corrosion not to be tooling contamination, but highlights an inherent problem.
ear of random failure Subsequent tests by the European Otto Graf Institute confirm that the corrosion resulted not from tooling contamination but from an inherent problem in the manufacturing process. Modified martensitic fasteners rely for their corrosion resistance on their smooth surface finish. The Otto Graf Institute concluded that “the corrosion is attributable to the influence of chloride commonly found in urban/industrial environments. The susceptibility of the screws depends on their surface finish; the surface finish was very uneven and had fissured areas locally, resulting from the manufacturing process.” What is alarming for the specifier, is the inconsistency of the modified martensitic product. All ten samples in the UK tests were selected from the same box, therefore presumably the same production batch. At the start of the test it was impossible to identify which three would corrode. That kind of random failure is simply not acceptable for specifiers seeking guaranteed performance.
The results of tests into fastener performance confirm that the new modified martensitic fasteners - offered by some suppliers as an alternative to austenitic - fail to offer a consistent guarantee against corrosion. In some cases, modified martensitic screws shows clear signs of corrosion after just four weeks atmospheric exposure. The evidence first came to light in May, following tests carried out in the UK. Fasteners used to attach stainless steel hardware to reinforced and unreinforced PVCu windows were tested in isolation, Product 400ss to avoid contamination from other Sample external sources, and in 4.8x16 SD No. modified application. martensitic (A) The natural exposure programme was carried out in an urban 1 O environment over a 28 day period. 2 O Test samples, ten of each, were R/T UH 3 subjected to temperatures varying 4 O from 5˚C to 23˚C. There were R/T 5 periods of rain and dry spells and 6 O varying degrees of humidity. 7 O As expected, the 300 series R/T 8 austenitic fasteners showed no 9 O visible signs of corrosion at the 10 O completion of the tests. In contrast, the modified martensitic fasteners in application showed visible signs of red rust on the threads within two weeks and rust under the head after four. In isolation, three of the ten samples of the modified martensitic showed red rust on the threads.
Product 300ss other 4.8x16 ST all austenitic (B)
O O O O O O O O O O
Product 300ss other M4x18 SD austenitic with carbon steel drill point (C)
W/TH UH W/TH UH W/TH W/T UH W/TH UH
O O O W/TH UH W/T
Product 300ss SFS SP2S 4.2x16 SD all austenitic (D)
Product Product 300ss 300ss SFS SPS other M4x16 SD 4.2x22 SD austenitic austenitic with with carbon steel carbon steel drill point drill point (E) (F)
O O O O O O O O O O
O O O
W/A
W/H
W/A
W/A
W/A
W/T
W/A
O O
W/A
W/T
W/A
W/H
W/A
W/TH
W/A
W/A
KEY SD = Self drilling product for reinforced steel/ aluminium profile ST = Self tapping product for unreinforced profile O = No corrosion visible
R W T H UH A
= = = = = =
Red rust formation Oxidation of zinc Visible on the threads Visible on the head Visible under the head All over
3
Robin Szymura checks to ensure that window suppliers are complying with Salford’s strict austenitic fastener policy whilst Peter Dunbevand looks on.
Tightening the screw spec These days the City of Salford is becoming well known for the tightness of its window specification. With a wide mix of housing stock - 34000 dwellings in total - the Council’s Engineering & Architect Division is demanding a 30 year life of its windows. With a £5 million annual maintenance budget at their disposal, the Pre-Paint Repair team make policing their specification a major priority. Nowhere is that more in evidence than in their window fastener policy where their commitment to austenitic screws is total. High Rise Around 15% of Salford’s council housing stock is high rise, built in the 1960s and 1970s to meet the demand to replace, quickly, the dilapidated slums depicted so graphically by painter L.S. Lowry. A further 10% of Salford’s portfolio is in medium rise, the remainder in pre- and post-war traditional dwellings. Wholesale PVC Following two pilot schemes in the early 1980s at The Valley Estate, Salford took the decision to go for wholesale PVC-U window replacement in 1986, with a programme to replace all metal windows, and the predominantly softwood timber windows, in the 1960s and 1970s housing. By 1997 virtually all the pivot windows in the high rise blocks had been replaced with PVC. Specifications require triple chamber construction, minimum wall thickness for the profile and are stringent about the quality and performance of the hardware. Salford rejected both tilt and turn and pivot options for high rise, in favour of top hung reversibles fitted with opening restrictors for safety.
4
All two storey buildings are fitted with inwardly glazed casement windows. Originally the specification stipulated cockspur handles. For security, mushroom espagnolettes are now required. Austenitic Benefits Initially the specification allowed fabricators to use their own discretion in selecting the fasteners which affix the hardware. It was a seminar staged by fastener manufacturer SFS Stadler Ltd which first drew the team’s attention to the fact the material from which a screw was made could significantly affect the long term performance of a window. Made aware of the benefits of austenitic screws Salford changed its fastener specification to require that screw fasteners shall be manufactured from austenitic (non-magnetic) stainless steel as BS 311 Part 2 with the exception of those fasteners used for reinforcement retention only. The ‘non-magnetic’ reference serves as a sharp reminder to any supplier hoping to substitute inferior fasteners for the specified item. It lies at the heart of Salford’s policing policy. The threat that contractors who breach the austenitic specification will be required to replace unsuitable screws is sufficient to win compliance. That the spec may marginally increase the cost of each window does not perturb Salford. Having seen the problems caused by corroded screws they know that the most cost-effective window is the one that is made right first time. Doing it right saves money in the long term. Equally, a tight spec allows all quality fabricators to tender for contracts on a level playing field, using the same high grade window components.
Around 15% of Salford’s Council housing stock is high rise. Pictured (left to right) Project Architect Peter Dunbevand; David Holland, Team leader of Technical Services Department, Salford City Council and Robin Szymura, Specification Manager of SFS Stadler Ltd.
5
Building trust With around 90% of its residents aged 70 or over, Anchor Trust has a special obligation to provide quality support, care and housing. A recent tightening of its window specifications reflects the thoroughness of Anchor’s approach, right down to the very last screw.
From a building maintenance perspective, the challenges facing Anchor are slightly different from those faced by other associations. Almost all of Anchor’s dwellings have been constructed during the past 30 years, the vast majority in the 1970s, in two and three storey blocks. As was the vogue in the 1970s, most were fitted with softwood windows and cills; at the time there were no statutory requirements to provide ventilation. Largely, Anchor managed to adhere to its target of 4 - 5 years external repainting programmes but, as experienced by so many other housing associations and local authorities, that didn’t prevent the problem of rot. Virtually all of the windows were single glazed and the resultant condensation meant frames rotted from the inside. Solution It was in the early 1990s that Anchor adopted the PVCu solution, initially creating their own performance specification to select appropriate profile systems and subsequently drawing on the LHC’s established expertise in the specification of windows. The switch to PVCu frames also heralded the switch to double-glazing as standard too. In 1995/6 around 3500 new windows were fitted in Anchor flats across the UK; in 1996/7 a further 3000. Foresight Unlike many others who have viewed PVCu frames as the ‘maintenance-free’ option, Malcolm Gara and his colleagues were quick to realise that, despite the maintenance cost-savings and excellent thermal performance offered by PVCu frames, to work effectively they still need caring for too. It is Anchor’s foresight in tightening the specification for some window components even beyond the standards laid down by the LHC requirements, that will safeguard Anchor from problems which others may face in the next few years. It was at an industry seminar that Malcolm Gara, Head of Property, was first made aware of the potential risks of permitting the use of carbon steel
6
Anchor has been fitting PVCu windows to its properties since the early 1990s.
or martensitic steel fasteners to affix hardware to PVCu window frames. He was so concerned about the possible risk of window failure and the potential risk to tenants, that he arranged a special briefing session for the Trust’s 27 property surveyors. The result was an amendment to the specification and a reinspection programme of previous installations to identify and eradicate any problems. Traditionally windowmakers have preferred to affix window hardware using coated carbon steel or martensitic steel screws, but both materials are intrinsically corrosive.
There’s more to choosing a fastener than simply specifying the material from which it is made. With over 500 different types of fasteners available for affixing hardware and reinforcement to PVCu frames, windowmakers and specifiers need professional guidance to make the right choices. For UK fastener manufacturer SFS Stadler Ltd., that resulted in the creation of a technical assessment team. Qualified field sales engineers, headed by Technical Manager Nigel Wood, provide advice on the most effective fastener for individual applications taking account of the security, load bearing and weather performance requirements. For window systems companies the team produces systems specific manuals to guide their fabricators in fastener selection. If you require input from the team contact Nigel Wood on 0113 208 5500.
Eliminating Excuses Only 300 series austenitic stainless steel is suitable, and the introduction of a bi-metallic fastener, with a hardened steel drill point and an intrinsically non-corrosive shank and head, eliminates any excuse for windowmakers not to provide the corrosion-free option. Evidence suggests that unless specifiers write in to their specification a requirement for austenitic fasteners, ideally with a manufacturer-backed ten year warranty, windowmakers will continue to try to fit inferior and inherently corrosive alternatives. There have been a number of incidents of window casements falling out, with potential risk to life, because of failed screws. Anchor now specifies SFS Stadler austenitic fasteners for all window fixings other than the retention of reinforcement within the profile. SFS provides a written warranty against corrosion, a separate third party product liability insurance, and provides an advisory service to window contractors to Anchor on the appropriate screws for new windows and remedial work. This report is adapted from an article which first appeared in Housing Association Building & Maintenance magazine.
Helping the specifier make the right choices
Gary Hampshire (centre) of Leeds window fabricator Roseville Enterprises affixes hardware whilst SFS’ Nigel Wood (left) and Neil Ackroyd look on.
7
For specifiers in the private and public sectors, security remains a key issue. On French and residential doors the hinge has traditionally been a potentially weak point. Now, a new range of all steel hinges, fitted with a specially designed security device, enables doors from most profile systems to meet the security requirements laid down in PAS024, which is currently in draft form. The six hinge range offers both face fit and butt hinge options, allowing the hinge to be affixed into reinforcement if required. The range allows for varying degrees of adjustability, ensuring that the doors are easy to fit and will continue to give optimum performance for their lifetime. The strength and durability of the hinges results from their all steel frame and sash barrel construction. Whereas hinges from other material may shatter on hard body impact, the SFS range will not. It also performs exceptionally well in soft body impact tests.
SFS Stadler Ltd Idsall House High Street Prestbury Cheltenham GL52 3AX Tel: 01242 585400 Fax: 01242 520682 and 153 Kirkstall Road Leeds LS4 2AT Tel: 0113 208 5500 Fax: 0113 208 5539
8
The SFS Group is an international manufacturer of fastening solutions for the construction industry. With operations in the UK, Switzerland, France, Germany, Italy and the USA, the Group invests over £20 million per annum in product design, development and enhancements to manufacturing plant and equipment .
Designed and produced by The Partners Group, York. Tel: 01904 610077
Security hinges on steel
