Glass Shop Fronts for Modern Retail Spaces

[edit] Introduction

Glass shop fronts are widely used in retail and commercial buildings where visibility, daylight and an open appearance are important considerations. They can provide large areas of transparent or translucent glazing while allowing shop displays to remain visible from the street. The design of a glass shop front needs to balance aesthetic requirements with structural stability, security, weather resistance, thermal performance, accessibility and safety.

The term glass shop front generally describes a glazed frontage forming the enclosure of a retail unit at ground-floor level. It may comprise glass panels within aluminium, steel or other framing systems, or may use more minimally framed arrangements. The appropriate configuration depends on the dimensions of the opening, structural requirements, the type of glazing, the building's location and the intended use.

[edit] Appearance and retail visibility

One of the principal advantages of a glazed shop front is the high level of visibility it provides between the interior and the street. Large areas of glazing can allow daylight into the retail space and make displays visible from outside, potentially contributing to the character and identity of the premises.

Glass can be incorporated into a wide range of shop front designs, including traditional framed arrangements and contemporary systems with narrow sightlines. Frames, mullions, transoms, doors, signage and other components can be coordinated with the architectural character of the building.

The use of extensive glazing can also make a relatively small retail space appear more visually connected to the street. However, excessive glazing can increase solar gains, heat loss and glare, so its extent and specification should be considered as part of the overall building design.

[edit] Glass types and safety

Safety is a significant consideration in the design of glazed shop fronts because the glazing may be located in areas where people can collide with it or where it could be subjected to impact. The type and thickness of glass should be selected according to the location, dimensions, support conditions and anticipated loads.

[edit] Toughened glass

Toughened glass is heat-treated to increase its mechanical strength and resistance to thermal shock compared with ordinary annealed glass. It is commonly used where increased impact resistance is required. When toughened glass breaks, it generally fractures into relatively small, blunt-edged particles rather than large sharp shards.

Toughening does not make glass unbreakable, however, and it should not be described as providing complete protection against forced entry. Once toughened glass has been processed, it cannot normally be cut or significantly modified without destroying the panel, so holes, notches and other required features need to be incorporated before toughening.

[edit] Laminated glass

Laminated glass consists of two or more sheets of glass bonded together with an interlayer. If the glass breaks, the interlayer can retain much of the broken glass in place, reducing the risk of falling fragments and maintaining a degree of integrity.

Laminated glass can therefore be appropriate where enhanced safety, security or post-breakage integrity is required. In some applications, a combination of toughened and laminated glass may be specified to provide both increased strength and retention of fragments after breakage.

The appropriate glass specification should be determined from the requirements of the particular installation rather than assuming that toughened glass alone provides the highest level of safety or security.

[edit] Durability, weather resistance and maintenance

Glass is generally resistant to corrosion, rot and many forms of weathering, making it suitable for external shop front applications. Its long-term performance nevertheless depends on the glazing system as a whole, including frames, seals, fixings, drainage and interfaces with the surrounding building.

Glass surfaces can accumulate dirt, pollution and deposits, particularly in busy urban environments. Regular cleaning may therefore be necessary to maintain transparency and appearance. Seals, gaskets, frames, fixings and other components may also require inspection and maintenance.

Glazing can be specified with coatings or treatments that alter its solar, thermal, optical or maintenance characteristics. Solar-control and low-emissivity coatings, for example, can influence heat transfer and solar gain. UV transmission can also be reduced through appropriate glass compositions or coatings, which may help limit fading of some internal finishes and merchandise. Such measures should be assessed alongside daylight, overheating and energy-performance requirements.

[edit] Installation and performance considerations

A glass shop front needs to be securely supported and properly integrated with the surrounding structure. Installation typically involves setting out the opening, preparing or installing the frame or support system, positioning the glazing, providing appropriate packings and seals, and checking alignment and movement.

The fixing arrangement must transfer the relevant loads safely to the supporting structure. External glazing is also required to resist environmental effects such as wind loading, while joints and interfaces need to accommodate movement and control the passage of water and air.

The performance of a shop front depends on the complete assembly rather than the glass alone. Frames, glazing systems, seals, doors and junctions can all influence thermal performance, weather resistance and acoustic performance. Careful installation is therefore important to achieving the intended performance and reducing the likelihood of problems such as water penetration, glass movement or premature seal failure.

Where the shop front forms part of a larger glazed façade or curtain wall system, it may be designed as part of that system rather than as an independent shop front. Curtain wall systems are non-structural external enclosure systems that transfer their own weight and environmental loads back to the primary structure. (Designing Buildings)

[edit] Security and design limitations

Although glass provides visibility and an open appearance, it can present security considerations. The resistance of a shop front to forced entry depends on the glass type, thickness, framing system, fixings, doors, locks and the design of the complete assembly. Toughened glass should not be regarded as inherently resistant to forced entry simply because it is stronger than annealed glass.

Where a higher level of security is required, laminated security glazing or specially tested glazing systems may be appropriate. Security shutters, grilles or other protective measures can also be incorporated where compatible with the architectural and operational requirements of the premises.

Extensive glazing can also introduce thermal and environmental challenges. Large areas of glass may increase solar gains during warm weather and heat loss during cold weather unless the glazing and frame system are appropriately specified. Solar-control glass, insulated glazing units, shading and suitable ventilation or building-services strategies can be used to address these issues.

[edit] Architectural and planning considerations

The design of a shop front can have a significant effect on the character of a building and the surrounding street. This is particularly important in historic town centres and conservation areas, where traditional shop front elements such as pilasters, cornices, stall risers and timber framing may contribute to the architectural character.

Replacing an existing shop front with a fully glazed modern design may therefore require consideration of the building's history, architectural significance and local planning requirements. In some cases, retaining or incorporating historic elements may be preferable to complete replacement. Historic shop fronts can include earlier forms of architectural glass, such as Vitrolite, which was widely used in twentieth-century commercial architecture. (Designing Buildings)

Glass shop fronts can provide an effective combination of visibility, daylight and contemporary appearance, but their suitability depends on more than aesthetics. The design should consider safety, structural support, security, thermal performance, weather resistance, maintenance and the architectural context of the building.

[edit] Related articles on Designing Buildings

• Curtain wall systems
• Glass mullion system
• Framed-type glass curtain wall
• Cladding for buildings
• Wall types
• Shop signs
• Pilaster
• Vitrolite
• Infill panel
• Types of cladding index