Internal glazing, safely

Cath McLean of Promat UK gives a technical breakdown on why the latest generation of fire resistant glazing allows internal glass elements to be designed to deliver multiple performance benefits – without compromising safety

Creating safe buildings is an absolute priority and strictly governed by the Building Regulations in all four UK nations. However, internal spaces still need to be comfortable, energy efficient, fit for purpose and aesthetically pleasing to be most practical, sustainable, popular with users and – in commercial terms – a valuable asset on which a healthy return can be yielded.

This is where today’s fire glass products and fully tested fire rated glazing systems can help; ensuring architects and specifiers do not have to compromise on design goals while meeting the required passive fire protection standard. This reduces the risk of the finished installation – whether a glass partition, screen or many other types of interior feature – falling short in terms of meeting the client brief.

Frameless and slim-frame internal glazing, typically butt-jointed to maximise light transmission, is a defining feature of contemporary interior design. Despite this trend running in parallel with a continuous toughening of fire safety standards, innovation in glazing technology has ensured that architects can still achieve their design intent.

Specified for a reason

There is no margin for error with fire rated glazing. To have complete assurance on the fire resistant glazing specification’s performance, the design must be supported by credible evidence that it will perform as promised. This is why a fully tested system approach has major advantages.

When a design is agreed, it is important to remember that any deviation from the assembly, such as substituting just one element with a supposed like-for-like product, could undermine performance. This would mean no certainty of the system’s ability to meet the specified fire rating in the event of a fire.

But this need not be a barrier to tailoring the glazing design to suit the building requirements. The multi-functionality of advanced glass products and an understanding of how to combine them can give interior spaces greater flexibility and perhaps, new purpose.

Better acoustic performance

Acoustic insulation is a key specification goal in many commercial and public spaces. Fire rated glazing already offers a higher acoustic rating than standard glazing due to the way it is manufactured. Promat Pyrosec 16 glass, for example, has a thickness of 17.3 mm which gives it an acoustic rating of 39 dB Rw (compared with 30 dB Rw for a ‘standard’ 16.8 mm acoustic glass).

But the acoustic rating can be improved even further with enhancements to the glass specification. Adding a PVB layer in a single glazed application such as a glass partition, for example, will enhance the sound reduction performance. So too would opting for a double glazed unit which utilises an intumescent fire-resistant gel within the cavity.

Added thermal benefits

Certain applications may need the design to achieve a higher level of thermal insulation as well as fire resistance. For example, vision panels between a warehouse and office areas overlooking production/operational spaces, or where the fire rated glass is on the outside of the building to prevent fire spread from one building
to another.

Here, the specification could be adapted to become a fire rated double glazed unit, with either an intumescent fire resistant gel cavity, or an argon filled cavity. A sealed unit comprising 6 mm glass, a 15 mm argon filled cavity and fire resistant glass, for example can offer a Ug value of 1.0 W/m2K in combination with an EI60 fire rating.

Internal climate & solar control

The role that today’s glass products can play in preventing summertime overheating and providing a stable internal climate is becoming increasingly important and valued, particularly given the recent introduction of Approved Document O to address this issue in domestic properties. Adding solar control functionality within the fire rated glazing specification is easily achievable, primarily by creating a double glazed unit which features a performance solar control product on the external face.

This was the requirement for a recent mixed use development on Kensington High Street in London. Glazing for this high profile building was specified to balance a 60-minute EI60 fire rating with solar control in very colour neutral double glazed units, which allow daylight maximisation (Lt 64) and achieve a solar factor of 35%.

Enhanced security & safety

Impact resistance, blast resistance and other design goals can also be incorporated into a fire resistant glazing specification. This is one of the most common types of enquiry from architects given how glazing must often protect people, and high value and sensitive assets in many commercial and public environments.

By combining different products, many different performance goals can be achieved in this area as two recent architectural specifications demonstrate. The first was for a data centre where a 120-minute fire rating was required along with a BS EN 356 P6B rating to protect key areas of the building in the event of a fire or security threat. Another project required a two-hour fire rating in combination with blast resistance for a major transport hub.

Understanding glazing’s potential & limitations

The key to developing an effective fire resistant glazing specification that meets other performance goals is to understand how to combine different products, the maximum sizes possible and framing arrangements, along with any limitations that could prevent targets being achieved. This is why it is crucial to consider how the glazing will help achieve the design intent at the earliest stage as the resulting specification could impact on the aesthetics, size and orientation of a glass feature – and even add functionality to a space that had not been previously realised.

The key is to think in bespoke terms about the glazing. Doing so will enable you to capitalise on the opportunity to create high quality internal environments which offer assured protection in the event of a fire and provide a high level of client satisfaction.

Cath McLean is segment manager – glass at Promat UK