Following recent news coverage regarding the manufacture and compliance of some reduced sightline insulating glass units, the GGF has addressed the issue from a technical and GGF policy perspective.
On the compliance with Building regulations, Steve Rice, GGF Director of Technical Affairs explained:
“Initially we need to clarify the issue as to whether or not narrow cavity IGUs comply with Building Regulations. In all countries within the UK there are provisions for non-compliance with the general thermal requirements in properties that are classed as heritage assets (listed buildings) and conservation areas where the use of compliant products would significantly change the fenestration of the building. For example in Scotland, clause 6.0.3 General guidance states:
“Work on existing buildings - as for other standards within Scottish building regulations, the energy standards apply to conversions and also work on existing buildings, such as extensions, conservatories, alterations and replacement work. However, in some situations, individual standards may not apply or guidance on compliance with the standards may differ for such work. The latter is usually to recognise constraints that arise when working with existing buildings.”
Steve continued, “Building Regulations in the other countries within the UK also have a similar allowance. The issue in question is not compliance with Building Regulations but compliance with the requirements of the Construction Products Regulations and through that, compliance with BS EN 1279-5:2005+A2:2010 – Glass in building – Insulating glass units – Part 5 Evaluation of conformity.
BS EN 1279-5 requires all IGUs to have Type Test (TT) evidence to Parts 2 and 3, component manufacture evidence to Part 4 and a system description in accordance with the requirements of Part 1. A Factory Production Control (FPC) is also required at a minimum level detailed in Part 6.
The Part 2, 3 and 4 test evidence is required to demonstrate durability of the IGU, to provide a reasonable service life.”
Russell Day, GGF Director of Home Improvement added, “In terms of the demand for the IGUs in question, it is not the narrowness of the cavity but the reduced sightlines of the spacer bar, some being as low as 5mm from edge of glass to top of spacer bar. This market demand is generated in the main, by local authority planning officers, in particular conservation officers, who demand that replacement glazing or windows into listed properties must be glazed into glazing rebates, either in the frame or sash that limits the dimension between edge of glass and top of spacer bar. This is of particular relevance where the sash is sub-divided into small panes such as is seen in Georgian style properties. Planners commonly restrict the width of glazing bars which sub-divide sashes into small panes, it is common to see these restricted to between 18 and 22mm, which in turn results in glazing rebate upstands in the range of 6 to 8mm, leaving a feather of 6mm to support and provide a level of strength to the window sash.”
Russell continued, “To ensure IGUs comply with these planning requirements the GGF aims to work with stakeholders across the supply chain. A number of years ago, an IGU manufacturer produced reduced sightline IGUs by cutting down existing 5mm high warm edge spacer bars to produce a spacer bar with a 3mm height and combine this with as little as 2mm or less sealant. It was reported that there was a high failure rate of these units which saw the introduction of a warm edge spacer bar manufactured with a 3mm high spacer. This has been marketed based on an edge-seal construction incorporating a minimum 5mm of sealant over the back of the spacer bar, giving a minimum sightline of 8mm. Although the spacer bar manufacturer has not been able to achieve passes to both Part 2 and 3 of EN 1279, they are continuing to work on developing a system that will achieve passes to both parts of the standard.
The issue that IGU manufacturers now have is that given planners are imposing these conditions on heritage buildings and in conservation areas, these non-compliant IGUs will be undoubtedly be manufactured by some companies.”
Phil Pluck, GGF Group Chief Executive addressed the issue at the GGF’s annual Members’ Day on 29th September. In Glaziers Hall, London in front of over 100 GGF Members, Phil announced the GGF’s position on the compliance of reduced sightline units.
“If a member chooses for their own advantage to breach the GGF rules or indeed the law, it is the GGF’s duty to inform them and to guide and support them to return within the boundaries of the GGF rules and the law. If they choose to ignore that guidance then upon a finding of guilt they will be expelled. We have evidence that that course of action has worked in the past. But we are not a policing authority.
However, if we find that a member is operating outside of the GGF Rules because of other authorities’ failings then it is the GGF’s duty to both guide that member and address the root cause that is putting that member under pressure to act in a way that takes them outside of the GGF Rules.
Reduced sightline units is an area that is simply not a case of black or white. Break the GGF Rules for your own advantage without cause then you are expelled. We must uphold the highest standards for the sake of the GGF and its members.
But if a member is part of a supply chain that puts pressure on them to supply or fit products that may breach standards then the GGF must do two things:
- Give definitive technical and legal advice to member - we have done that in this case.
- Highlight to other parties that unless they uphold the same standards then inevitably this will isolate our members and make them vulnerable.
Architects, planning authorities, heritage groups, Chartered Trading Standards Institute all have a part to play to address an issue that affects us all.
Simply isolating and punishing one part of that supply chain i.e. our member will not address the underlying issue that affects the entire industry. We have and are continuing to try and engage the whole group of stakeholders in resolving this issue. The expulsion of a few members will not solve the issue surrounding this topic and so GGF will continue to take a holistic approach to this problem.”
The GGF has worked mainly in Scotland on this issue, having many meetings with Historic Environment Scotland, Building Control, MSPs and Scottish ministers, Trading Standards and local authority planning departments. Generally the view from most is that although they accept the reduced sightline IGUs being supplied do not comply and although early failure of these IGUs has been experienced, the view of most agencies is that Heritage takes precedence to compliance with BS EN 1279.
The GGF has referred one manufacturer to Trading Standards and although they will not confirm whether or not they have investigated and given they are still trading the same products, it can only be assumed that Trading Standards have yet to deal with the case.
Steve Rice took an overarching industry view adding, “In terms of the supply of components being used to manufacture these products, stopping supply will result in a reversion to the practice of cutting down an existing product that is likely to result in a return to significant numbers of IGUs failing very prematurely. The GGF has undertaken a number of site inspections of this type of IGU installed in timber windows where the homeowner has complained of IGU failure (condensation in the cavity). We are informed a number of these are pursuing a legal resolution to their issue.”
Phil Pluck concluded, “The GGF remains committed to addressing the root causes of this issue but in order to do so, other stakeholders such as policing and planning authorities must accept that an issue exists, and that a joint approach is required to resolve it. GGF, on behalf of the industry and its members remains open to such discussions"
The GGF has recently published a new guidance document;
Insulating Glass Units (IGUs) - Conforming to the Construction Products Regulation (CPR) . This is available as a free [ download ] to all in the industry.
The GGF has also just launched a new guide for Members only entitled;
A Guide to the Planning Process and its effect on the Replacement of Windows and Doors in England. This is now available for free download to GGF Members only.
The GGF Heritage Window Group is meeting on 19th October in Birmingham and all Members are invited. If non-Members wish to attend, then please contact firstname.lastname@example.org.
[ Letter to The Editor - Breaking the law with Heritage Glazing?, Colin Torey , Saveheat Group ]