Structural Glazing FAQs
The term ‘structural glass’ refers to any type of load-bearing glazing. In place of a traditional wall, made of materials such as bricks, large panels of thick toughened glass are installed. There are lots of ways to integrate structural glazing into building design, including walls, doors, roofs, and floors.
The glass is an integral structural element, bearing weight horizontally and vertically with minimal additional support. Glass beams or fins, steel struts, spider fixings, and silicone sealants can be used to secure the glass panels without being too visible. This creates a practically frameless appearance.
The location, environment, and intended purpose of the structural glass will determine the size, shape, thickness, and bonding mechanism. This has to be carefully calculated, because structural glazing must withstand a variety of stresses, from wind and temperature changes to physical loads.
This type of architectural glazing is specially designed to be capable of supporting significant weights and transferring them to the building’s core load-bearing structure. Being more rigid than other traditional construction materials, structural glass can resist deformation well.
Loads can be distributed evenly through different techniques. Bonding structural glass panels to the building’s structure using a specifically formulated, high-performance silicone adhesive and sealant can achieve a seamless appearance, which is popular for modern commercial buildings.
Point fixing systems can discreetly attach panels to the building with minimal framing using small metal clamps. With bolted fittings, metal bolts are inserted into drilled holes in the panels to hold the glass in place elegantly. Metal framing can also be used if that aesthetic is preferred.
Structural glass designs are always meticulously checked to make sure that the correct calculations are used to determine the most suitable type of glass, installation style, and fitting materials. This is especially important in environments with potential exposure to severe weather conditions.
In addition to its strength and rigidity making it suitable for use in load-bearing structural elements, many buildings use structural glazing for its transparency, as it’s put to best use in areas where unobstructed views and natural light transmission are desirable – such as curtain walls and skylights.
Probably the most common and widely seen application is structural glass facades, which give larger buildings a sleek and modern look while maintaining insulation and energy efficiency. Some buildings use structural glazing for the atrium only, creating a visually impressive light-flooded feature.
Aside from windows and walls, structural glass can also be used for staircases – either replacing traditional balusters and handrails, or using walk-on glass for the steps – and for landings, mezzanines, and balconies that require safety barriers without disrupting the view below.
Bridges and walkways in commercial buildings also tend to use structural glazing to keep the space as open as possible while meeting performance requirements. The glass can be used for the floor, barriers, or canopies above to provide some shelter without blocking the light from above.
These are just some of the many possible ways that versatile structural glazing can be applied in various building designs and property styles.
There are countless benefits of using structural glass over other building materials, like wood, concrete, and metal, in certain applications. The most obvious is that structural glazing is simply far more aesthetically appealing, especially for multi-storey buildings wanting to display a contemporary look that attracts more people.
The second most popular reason for choosing structural glazing is that it reduces dependence on artificial lights, instead allowing sunlight to spread through spaces that would otherwise be darker and closed off. This is important for our health, as exposure to natural light is necessary to regulate biorhythms and improve productivity.
The toughened or laminated glass specially manufactured for structural use is also extremely robust, ensuring you’ll get great value from your long-lasting investment. It’s highly resistant to scratches, corrosion, and temperature changes, as well as being strong enough to ensure safety and security.
Cost-effective, sustainable, and versatile – structural glazing can help to reduce sound transmission and heat loss, all while looking spectacular and giving your building a distinct architectural style. Clever use of structural glass can make properties more attractive and energy efficient, thereby increasing their value, too.
One of the biggest advantages of structural glazing is that the lack of framing systems gives architects and designers more opportunities to create truly stunning installations of glass for their buildings. This allows a much wider scope and greater flexibility in creating a completely bespoke design.
The only factors restricting the maximum size of structural glass panels are your budget and site access limitations. The thickness of the glass will help to increase the building’s energy efficiency, with thermal technology maintaining an ambient temperature instead of trapping too much heat.
Large expanses of glass are eye-catching from the outside and offer unrivalled open views of the surrounding area from the inside. Not only does it physically increase usable interior and exterior space, but it also tricks the eye into thinking it’s even more spacious due to the flood of light.
There’s a lot of in-depth engineering involved in a successful structural glazing installation. The physical performance of each glass panel is far more important than how it looks, which is why so many calculations go into ensuring that your bespoke glazing is structurally sound.
Factors that require extensive consideration when selecting structural glass qualities include:
- Thermal insulation
Structural glass is given a ‘Ug’ value according to the amount of thermal energy that can pass through the centre of the pane itself. The lower the value, the better the insulation; you should never go for glass with a Ug value of more than 1.2 W/m2K for structural glazing.
Th ‘Uf’ value refers to the thermal performance of the framework, while ‘PSIG’ indicates the performance of glazing spacers. These can all be combined into an overall ‘Uw’ value, sometimes referred to as simply the U value, using test methods standardised by BS EN 673:1998.
- Acoustic reduction & fire rating
You may be familiar with seeing sonic insulation ratings in decibels, but acoustic reduction values are represented by an ‘Rw’ figure for structural glass. Decibels measure acoustic power, and hertz measure vibration frequency; both go into the calculations for Rw standardised by EN ISO 717-1.
As for fire-rated glass, it needs to be fire-tested at its full size as per the intended installation before it can be used for structural purposes. Any fixings will also need to be fire-rated. You can find out more about how fire ratings for glass work on our Fire Rated Glass Partitions & Doors page.
- Line load & maintenance load
Since the glass is expected to bear a heavy structural load, your design must be tested to ensure that it meets all the necessary load-bearing requirements. You cannot legally install structural glass that is not fit for purpose due to the obvious safety risks, which is why prior testing is mandatory.
Vertical glass panels must be able to withstand a particular line load – such as the weight of a person leaning on a glass barrier. The glass specifications and fixings must bear the appropriate load for its intended purpose. The same applies to horizontally installed panels, which must be able to bear an adequate maintenance load – like the weight of a person accessing a roof for repairs.
Exterior walls and facades will also need to withstand a wind load of no less than 0.5kN to ensure that the structural glass won’t crack, bow, or break under the pressure of strong winds. Buildings by the coast or at high altitudes are likely to have much higher wind load requirements.