Glazing Bar Spans

Versatile Glazing Solutions with Robust Structural Support.

Ilkey skylights - commercial glazing services
Green Park Station roof glazing, Bath - glazing bar spans

We offer an extensive range of glazing systems designed to achieve large spans, catering to the diverse needs and aesthetic preferences of most designers. Our selection is versatile and robust, ensuring that regardless of the architectural vision, we have a solution that fits perfectly.

To further enhance our service, we provide a complimentary structural calculation for all projects. This invaluable service ensures that we supply the correct strength glazing bar and the appropriate glass thickness, adhering to all relevant codes of practice. These calculations are critical for maintaining the structural integrity and safety of the glazing installation, giving you peace of mind that your project meets the highest standards.

It is essential to note that our glazing systems must always be fixed to other structural supports. These supports require precise pitching to the roof slope to ensure both air and weather-tightness. Proper installation is crucial for the long-term performance and durability of the glazing system.

By offering these comprehensive services and ensuring meticulous attention to structural details, we aim to provide not only aesthetically pleasing but also highly functional and reliable glazing solutions for all types of projects. Our expert team is dedicated to supporting your design aspirations while ensuring technical compliance with industry standards.

Withington Baths, Manchester commercial glazing services
Victoria Baths restoration, Manchester - glazing bar spans

Glazing Bar Spans

The span of roof glazing is classified as the downslope dimensions between the centre-lines of the fixing positions rather than the glazing bar length which is always longer than the span.

Achievable glazing bar spans are dependent upon many factors, including:

  1. Site altitude
  2. Distance of site from the sea
  3. Surrounding structures (built up area or open countryside)
  4. Glazing Type (enclosed roof or open canopy)
  5. Height of glazing apex from ground level.
  6. Pitch of glazing
  7. Glazing bar centres
  8. Roof shape
  9. Local wind speeds
  10. Local snow loads
  11. Snow drift loadings based on adjacent structures
  12. Weight of glazed infills
  13. Maintenance loadings
  14. Additional loadings imposed on the glazing system

It is therefore clear to see that you should not order glazing bars without seeking our guidance first.

We are able to carry out a free job specific calculation on every project to ensure that the glazing bars we provide can be proved to be sufficiently robust enough to withstand all possible loadings that the system will be subjected to.

Design Notes

Maximum glazing bar spans stated in the charts contained on this page are based on a generic site close to sea level, 30km away from the sea, 5m height of glazing from ground level, a duo-pitched roof shape, a 15° roof pitch and glazing bars being spaced at 600mm centres.

Single glazed data is based on a 6mm thick glass infill whereas double glazed data is based on 2 x 6mm thick glass infills.  Any deviation from these variables can significantly alter the maximum achievable span so please do contact us for expert guidance of this subject.

On deep glazing (slope lengths over 3200mm) a structural intermediate purlin (by others) is usually introduced into the design at the mid span position to enable a lighter glazing bar section to be used. Because glass over this length is not available in a single piece as standard, a convenient and common place to join the glass is over the intermediate purlin.

Our aluminium glazing bar ranges are available in lengths up to 6000mm-7500mm but will require intermediate support at these lengths.

Skyline Box Span Chart

Performance Data for Skyline Box Patient Glazing Bars ~ Compatible with our 4Edge Pro System

Bar Section
SPG5
SPG7
SPG10
SPG15
Box Depth (mm)
50
75
100
150
Lxx-mm4
459,350
1,043,625
1,861,293
4,732,206
Zxx-mm3
17,495
28,284
39,405
74,053
Roof Span (mm)*
Double Glazing
1450-3440
2200-4230
2930-4880
3920-7000
Single Glazing
2440-4000
3310-5000
3840-5750
4860-7500
Canopy Glazing
2650-3830
3460-4700
4000-5430
5050-6830

The glazing bar spans shown above are based on using 6mm thick glass for the double glazed, single glazed and canopy types, and the bars being spaced at 600mm centres. We will select the appropriate glazing bar for each contract. Spans are dependent upon the site location and exposure rating, site altitude, distance from the sea, height of glazing from ground level, shape of the roof, pitch of glazing, glazing bar centres, glass weight, wind speeds, snow load, dead load and maintenance loads.

* The above spans for each glazing bar have two values. The lower span values are calculated using the most extreme environmental loadings possible in the UK whereas the higher span values are based on the least extreme. Due to the wide range of these values it is therefore essential that we are supplied with the site postal code to enable us to calculate the correct glazing bar type for every project. There are a large number of variables which are used to determine the maximum span of the glazing bars so please do not attempt to buy any glazing bar materials from us without first allowing us to carry out the necessary calculations for your project.

Skyline Span Chart

Performance Data for Skyline Patient Glazing Bars ~ Compatible with our 4Edge Pro System

Bar Section
SPG2
SPG3
SPG4
Fin Depth (mm)
55
75
100
Lxx-mm4
240,628
500,995
1,296,896
Zxx-mm3
5,032
8,318
18,875
Roof Span (mm)*
Double glazing
1050-2630
1520-3530
2450-4470
Single Glazing
2000-3290
3500-4220
5000-6000
Canopy Glazing
1510-2810
1950-3610
2930-4970

The glazing bar spans shown above are based on using 6mm thick glass for the double glazed, single glazed and canopy types, and the bars being spaced at 600mm centres. We will select the appropriate glazing bar for each contract. Spans are dependent upon the site location and exposure rating, site altitude, distance from the sea, height of glazing from ground level, shape of the roof, pitch of glazing, glazing bar centres, glass weight, wind speeds, snow load, dead load and maintenance loads.

*The above spans for each glazing bar have two values. The lower span values are calculated using the most extreme environmental loadings possible in the UK whereas the higher span values are based on the least extreme. Due to the wide range of these values it is therefore essential that we are supplied with the site postal code to enable us to calculate the correct glazing bar type for every project. There are a large number of variables which are used to determine the maximum span of the glazing bars so please do not attempt to buy any glazing bar materials from us without first allowing us to carry out the necessary calculations for your project

Traditional Span Chart

Performance Data for Traditional Patient Glazing Bars ~ Compatible with our 4Edge Pro System

Bar Section
TW1
TC1
TW2
TC2
TW3
Bar Depth (mm)
60
65
80
80
100
Lxx-mm4
204,902
210,287
408,701
400,031
947,421
Zxx-mm3
4,641
4,913
8,101
8,049
17,582
Roof Span (mm)*
Double Glazing
Single Glazing
1340-3160
1340-3160
1770-4170
1770-4170
2610-5560
Canopy Glazing
1450-2690
1450-2690
1920-3560
1920-3560
2830-4590

The glazing bar spans shown above are based on using 6mm thick glass for the double glazed, single glazed and canopy types, and the bars being spaced at 600mm centres. We will select the appropriate glazing bar for each contract. Spans are dependent upon the site location and exposure rating, site altitude, distance from the sea, height of glazing from ground level, shape of the roof, pitch of glazing, glazing bar centres, glass weight, wind speeds, snow load, dead load and maintenance loads.

* The above spans for each glazing bar have two values. The lower span values are calculated using the most extreme environmental loadings possible in the UK whereas the higher span values are based on the least extreme. Due to the wide range of these values it is therefore essential that we are supplied with the site postal code to enable us to calculate the correct glazing bar type for every project. There are a large number of variables which are used to determine the maximum span of the glazing bars so please do not attempt to buy any glazing bar materials from us without us first allowing us to carry out the necessary calculations for your project.

Heritage Span Chart

Performance Data for Heritage Patent Glazing Bars

Bar Section
No7 SG
No7 DG
Bar Depth (mm)
53
53
Lxx-mm4
136,847
136,847
Zxx-mm3
4,189
4,189
Roof Span (mm)*
Double Glazing
1350-3270
Single Glazing
1430-3570
Canopy Glazing
1540-2800

The glazing bar spans shown above are based on using 6mm thick glass for the double glazed, single glazed and canopy types, and the bars being spaced at 600mm centres. We will select the appropriate glazing bar for each contract. Spans are dependent upon the site location and exposure rating, site altitude, distance from the sea, height of glazing from ground level, shape of the roof, pitch of glazing, glazing bar centres, glass weight, wind speeds, snow load, dead load and maintenance loads.

* The above spans for each glazing bar have two values. The lower span values are calculated using the most extreme environmental loadings possible in the UK whereas the higher span values are based on the least extreme. Due to the wide range of these values it is therefore essential that we are supplied with the site postal code to enable us to calculate the correct glazing bar type for every project. There are a large number of variables which are used to determine the maximum span of the glazing bars so please do not attempt to buy any glazing bar materials from us without first allowing us to carry out the necessary calculations for your project.

Please note that due to the manufacturing process of our Heritage lead covered steel glazing bars, we cannot supply this product in lengths exceeding 3350mm (11’-0”) regardless of whether intermediate supports are provided. If a Heritage glazing bar is required to exceed this length then the design must incorporate a break/tier to overcome this limitation (see above).

Granby Street, Leicester - glazing bar spans
commercial glass solutions - Derby Market