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Our Skyline Box range of glazing bars offer an economical roof glazing solution when compared with curtain walling roofing systems. The glazing bar's strength is provided by an internal box section. The glazing bar is weathered by a screw on pressure cap (PC1) with a choice of plain (PC2) or ornate (PC3) cosmetic outer snap-on cappings to conceal all fixing screws.

When used with high performance double glazing units with warm edge spacer bars and argon gas filling this system can achieve an overall U Value of 1.4W/ m²K to comply with Building Regulation Document L.

Our Skyline range of glazing bars offer an economical roof glazing solution incorporating slim sightlines. The glazing bar's strength is provided by an internal stalk (or fin) which is cut away at the top and bottom main fixing positions.
An internal snap-on ornate capping system (PC4) is also available if desired to fully conceal the internal stalk giving the appearance of a feature timber rafter.

When used with high performance double glazing units with warm edge spacer bars and argon gas filling this system can achieve an overall U Value of 1.4W/ m²K to comply with Building Regulation Document L.

Timber rafters (supplied by the builder or joinery sub-contractor) will create an appealing visual effect inside any home and are totally protected from the effects of weathering by our externally clad Rafterline Patent Glazing system.
Due to the pleasing aesthetics of aluminium and timber materials our Rafterline system is the most popular specifiers choice for domestic projects.

When used with double glazing and thermal breaks this system is easily capable of providing an overall U Value of 1.6W/ m²K to comply with Building Regulation Document L.

Our Traditional patent glazing system remains our customers most popular choice for use on unheated spaces such as Railway Stations, glazed canopies and covered ways where thermal properties are not a consideration.
This system has been installed on thousands of projects nationwide and is available with a choice of capping systems to suit your needs.
A truly great glazing system combined with economy and a proven track record. 30,000m² of this glazing system has been installed by us on many major railway stations throughout the UK in recent times.

This system is capable of accommodating solid or multi-wall polycarbonate sheets or double glazed units up to 28mm thick if used on unheated spaces or where compliance with Building Regulations Document L are not a consideration.

Our 'Heritage' Patent Glazing Bar range is truly unique amongst roof glazing systems; there are no alternative products available on the market which can match an original lead covered steel patent glazing bar which originates from the Victorian era. This range has been manufactured by us unaltered for over a century and is the perfect product for listed buildings and for use in the refurbishment of significant and historic buildings. This system is also still very popular for new build projects and should not to be overlooked on today's modern buildings where a unique character look is desired.


Patent glazing has an excellent record of public safety over many years.
The following information can serve as a guide for selection of a suitable safety glass in any of our overhead patent glazing systems. All of our Patent Glazing systems can be supplied with glazed infills to meet Non-Fragility ratings in accordance with ACR[M]001:2014 Test For non-fragility of large element roofing assemblies as well as the CWCT TN67 document: Testing and assessment for Safety and fragility of overhead glazing.


  • Safety First!
  • Glass Type based on height from foor level
  • Glass thickness
  • Non-Fragility

Safety First

In sloping patent glazing situations, it is a requirement to install glass which will either tend to stay in place if it is cracked (Wired and Laminated Safety Glass fall into this category) or to fracture into relatively harmless pieces (Toughened Safety Glass falls into this category) which are less likely to cause serious injury, if they fall, than sharp shards of annealed glass.

BS 5516: 2004 Code of practice for vertical and sloping patent glazing is currently the only regulation or standard which gives any recommendations about the type of glass to use in roofs.

For single glazing, either wired, laminated or toughened glass is recommended by BS 5516, while double glazed units should have one of the three types as the lower pane.

With regard to toughened glass, BS 5516 suggests that, if the lower pane of a double glazed unit is toughened, then the upper pane should also be one of the three recommended types of glass.





Recommendations for the thickness of glass used in sloping Patent Glazing

Glass in sloping patent glazing throughout its long history has generally been installed at a thickness of 6mm. This is still by far the most common thickness used on all patent glazing projects and patent glazing's excellent safety record shows that a 6mm glass is both safe and practical when concerned with public safety. If you need to consider the safety of people working on the roofs then you may wish to consider using a thicker glass to help reduce the risk of falling through the glass or designing barriers to prevent people being able to fall onto the glass from a higher roof level.

Due to the relatively narrow widths of glass used in patent glazing, there is generally no need to use a glass thicker than 6mm to withstand all the usual loadings that the glass is likely to be subjected to. Patent Glazing is predominantly situated in a sloping situation, therefore in the event of a glass breakage and depending on the location, consideration may need to be given to the protection of the public below from falling glass.

As shown on the table on the previous tab page, Toughened glass should not be used above 6mm thick as an inner pane in patent glazing if the height is between 5 metres and 13 metres above floor level. When broken, Toughened glass at 6mm thick fractures into small pieces (called dice). As these particles do not have the sharp edges and dagger points of broken annealed glass, it is regarded as a safety glass. While these dice may cause minor cuts, it is very difficult to cause a severe injury with them, provided the fragments are small enough. Toughened glasses thicker than 6mm however, if installed as an inner pane above 5 metres from floor level may cause harm to the public below when broken due to the increased weight of the glass which is falling to the ground.

Toughened glass of any thickness should not be used in sloping glazing as an inner pane if the height is over 13 metres from floor level because the broken glass pieces (dice), falling from such a height, have a more likely chance of causing injury to people below than from a lower height.


Non-Fragility and Patent Glazing

The British Standards for Patent Glazing, BS5516 parts 1 & 2 provide guidance on the use of suitable safety glass as outlined in the previous tabs on this web page. These standards are concerned solely with protecting the public from injury in the case of glass breakages and failures from roof patent glazing.

In the last few years a greater amount of emphasis has been placed on the protection of people who are actually carrying out work on roofs. Every year there are preventable deaths ocurring on buildings due to people falling through fragile roofing materials. Several of these accidents are associated with in-plane plastic/polycarbonate type rooflights which have been walked on accidentally resulting in the person falling through the roof. Other accidents are due to people falling from a higher roof level onto a fragile material onto a lower roof level.

It would be very difficult for a person to accidentally walk onto a roof patent glazing system by mistake. Also, if there is a possibility of a person falling onto a roof Patent Glazing system from a higher roof level then the Building Designer would ensure that barriers are placed at the edges of the higher roof level to prevent this from ever happening. Patent Glazing continues to have an excellent safety record for these very reasons.

Two seperate Non-Fragility tests for roofing materials have been developed independently of each other. The Advisory Committee for Roof Work have published a document titled ACR[M]001:2014 Test For non-fragility of large element roofing assemblies. 5th edition (red book). Another Non-Fragility test has been devised by The Centre for Window and Cladding Technology titled TN 67 Safety and fragility of overhead glazing: testing and assessment.

These tests have been developed over recent years in an attempt to reduce the number of deaths and injuries associated with people falling through fragile roofing materials. Compliance with either of these test requirements does not currently form part of any law or British/European Standard (statement written in 2014) however an ever increasing number of Architects are choosing to specify that Patent Glazing systems used on their projects should be used which have been classified as Non-Fragile by one or both of the above mentioned test criteria(s).

We have had several of our Patent Glazing systems offically tested for Non-Fragility compliance by independent testing bodies and are pleased to report that our systems perform admirably and have all been rated as Non-Fragile Assemblies. Due to the fluid changes that are constantly occuring in the Non-Fragilty testing field we found it necessary to commission the design and installation of our own steel framed test rig at our premises in Dewsbury to enable us to carry out multipe tests of our patent glazing systems when the need arises. Due to the flexible nature of Patent Glazing designs there are a multitude of combinations that require test based results which are governed by span, glazing bar centres, slope of glazing, glass type and glazing system.

We have carried out many tests and can state that all of our Patent Glazing systems can achieve a Non-Fragile rating in accordance with the ACRM test and the CWCT test if the patent glazing is installed at any pitch with a 3 metre maximum span , a maximum glazing pane width of 750mm and a laminated glass type of at least 8.8mm thick. For double glazed tests we have used outer panes of 6mm thick toughened glass with a 8.8mm lamianted inner pane. It is possible to achieve a Non-Fragile rating using thinner glass types under certain conditions but we would suggest that these are not generally considered if you are seriously considering using robust materials.