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CPD 6: Glass Barrier Systems

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This module looks at different types of glass barrier system and provides a guide to different methods of mounting them. It is sponsored by CR Laurence

How to take this module

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To take this module read the technical article below and click through to a multiple-choice questionnaire, once taken you will receive your results and if you successfully pass you will be issued automatically with a certificate to print for your records.

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Types of glass barrier system

Glass barrier systems can be used in a range of applications, both internally and externally, providing an attractive, minimalist appearance. There are three common types of glass barriers:

  • Full-height barrier The glass forms part or the whole of a wall element. The barrier should be designed in accordance with British standard BS 6180 if any part of the glass falls below the minimum barrier height.
  • Barrier with a glass infill panel The top rail and baluster form the main frame and should be designed to withstand the loads applied to the top rail. The glass should be used simply to form the infill panels and provides no support to the main frame.
  • Free-standing glass protective barrier The glass should be designed to withstand the design loads. Each glass plate is clamped to the structure along its bottom edge, the handrail is attached to the top edge of the glass and there are no balusters.

Free-standing barriers will be the focus of this CPD module. There are two types of glass that can be used as barriers with the Taper-Loc system:

  • Monolithic toughened glass 10mm thickness is suitable for windscreens and partition systems only. The 12mm, 15mm thicknesses are suitable only for balustrading. The 19mm thickness meets ASTM, BSI, and DIN tolerance standards.
  • Laminated toughened glass Thicknesses of 13.52mm, 17.52mm, 21.52mm and 25.52mm are available.

Ecobuild

CR Laurence’s Taper-Loc system was used to install a free-standing barrier with laminated, toughened glass at this residential project in Cannes, France

Relevant standards for free-standing glass barrier systems

The most important British standard for glass barriers is BS 6180: 2011 — “Barriers in and about buildings”. This provides recommendations for the design and construction of temporary and permanent barriers, provided in and about buildings and places of assembly, such barriers being positioned and designed to protect people from hazards and to restrict or control the movement of people or vehicles.

Article 8.5 contains specific guidance on free-standing glass barriers - 8.5.2 states that where the barrier protects a difference in level greater than 600mm, a handrail should be used, unless it is a laminated toughened glass construction, which would remain in situ if a panel fails. Continuous fixing should be used for attaching the hand rail to the glass, or individual fixings where calculations or tests demonstrate that component failure will not occur.

Article 8.6 deals with impact resistance. All systems should be maintained in line with article 8.7, which states that all glass should be regularly cleaned and fixings should be checked for corrosion and loosening.

Formerly, BS 6399-1: 1996 provided dead and minimum recommended imposed loads for use in designing buildings. However, this is now incorporated in BS 6180 as Article 6.2.

Manufacturers may also seek certification under independent standards, such as the International Code Council Evaluation Service (ICC-ES), which is based in the US. ICC-ES is accredited by the American National Standards Institute and carries out technical evaluations of building products to ensure they are compliant with international building codes. In January 2013, CR Laurence’s GRS Glass Railing System for monolithic glass achieved ICC-ES certification, the first such system to do so. The report is available to download free at www.icc-es.org.

Methods of installation

For free-standing glass barriers, the panel is anchored in a channel, usually of steel or heavy aluminium, known as the “base shoe”. This shoe can be embedded in concrete, welded to a steel substrate, surface or fascia-fixed using Hilti-type concrete anchors, or surface-fixed using socket-head machine bolts. There are two methods of fixing the glass to the base shoe.

  • Wet glazing This method sets the glass by pouring expansion cement or applying structural silicone around the base of the glass. The advantages of this approach are that the materials tend to be cheaper, it is resistant to water penetration and it restricts glass movement.

The disadvantages are that it is costly to realign the barrier if it is installed incorrectly, and it requires significant workmanship. This puts up the cost and slows the installation time - for example, special tools are needed to pour the cement in, it requires time to set, and the glass often needs cleaning after installation.

  • Dry glazing This method sets the glass by using a vinyl gasket material instead of silicone or expansion cement. Often, a “shoe” bracket or isolator is applied to the bottom of the glass and wedges are driven in between the bracket and the base shoe with a hammer. This relies on the installer to gauge how many times to hit the wedge into place, but generally less workmanship is required on site, which brings the cost down in comparison with wet glazing systems. Traditionally, dry glazing systems have been regarded as less strong than their wet counterparts, as the gasket can shrink or roll in the pocket, placing uneven stress on the glass, and allowing it to “walk”.

A variation on the dry glazing system for free-standing glass balustrades is the Taper-Loc system. Instead of using wedges driven into place with a hammer, the Taper-Loc system uses tapered high-strength reinforced nylon plates to lock toughened or toughened laminated glass into a heavy aluminium extruded base shoe. An installation tool slides the tapers horizontally into the base shoe on either side of the glass and compresses them together. When compressed, they expand and lock in place. A torque wrench tightens them further.

The system is intended for both interior and exterior weather-exposed applications and is suitable for both toughened monolithic glass (between 10 and 19mm) and laminated toughened glass (between 13.52 and 25.52mm). A different base shoe is required for each thickness. The 10mm thickness is suitable for windscreens and partitions only. An important advantage over wet glazing systems is that the installation tool can also be used to loosen the tapers for glass realignment or replacement.

Hand, guard and cap rails

  • Hand rails Continuous fixing should be used for fixing the hand rail (also commonly called a grab rail) to the glass, as individual fixing points may introduce unacceptable stress concentrations.

The hand rail should be attached to the glass in such a manner that, should a glass panel fracture, the hand rail:

  • will remain in position
  • will not fail if the design load is applied across the resulting gap.

This condition may be relaxed where the glass panel is an end panel and protects a difference in level of 600mm or less - for example, at the foot of a flight of stairs. In cases where an end pane protects a difference in level greater than 600mm, there would normally be some adjacent structure to which the hand rail could be attached, thus enabling it to meet this condition.

  • Guard rails Whereas hand rails are normally intended for guidance and support, guard rails are intended to prevent accidental falls. They take the form of a barrier erected along the open edges of a floor opening, wall opening, ramp platform, runway, balcony, or other elevated area to guard against falling off the edge.
  • Cap rails This is the top member of a glass barrier system, but it may also be considered as a hand rail in stair applications, as long as code requirements are met. They are available in a variety of sizes and finishes to accommodate monolithic and laminated toughened glass. Custom profiles are also available.

How to take this module
To take this module read the technical article below and click through to a multiple-choice questionnaire, once taken you will receive your results and if you successfully pass you will be issued automatically with a certificate to print for your records.

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