When considering a bespoke design package, it is imperative that a design sales meeting is conducted to ensure that all aspects of a glass structures design is considered. There are huge advantages to a structures aesthetics and performance, when considered and every effort should be made to ensure that the design brief meets the client’s expectations.
We have listed many of the main considerations when utilising structural glazing below.
Structural Glazing is one of the most cost effective contemporary solutions available. Structural Glazing is typically 17% - 23% more cost effective than that of a Frameless Glazing equivalent and 20% - 25% more expensive than Framed Glass (Curtain Walling/Patent Glazing) solutions.
Structural glazing systems offer a high level of flexibility within design and may be utilsed in most glass design applications. Should the glass design require windows or doors (typically framed), these items may be set back flush with the external glass face. The glass units are provided with a black spacer and silicone seal as standard. It is worth noting that polysulphide sealed glass units are not suitable for structural glazing applications due to the exposure to UV light. Due to the blacked out area applied to the glass units inner pane and subsequent differentials in expansion. Float laminated glass (unless of significant thickness) should not be utilsed in this application and should a laminated inner pane be required, a toughened laminated glass should be utilised. Necessary adhesive engagements and glass clearances must be maintained and these requirements do change in applications such as walk-on glass floors. In vertical or near vertical applications at height, the glass should always be mechanically retained with the use of concealed brackets/clamps. Structural glazing systems may be modified to provide a modular installation design. Where the glass is adhered to a modular designed frame within factory conditions. This method should always be considered, especially when the contracts installation programme falls within months of anticipated heavy downfall and/or extreme cold conditions.
As structural glazing systems do not rely on internal weep systems and subsequent drainage, they may be installed at as low as 3-5 degrees pitch (subject to application). In fact external walk on glass specifications are often installed as low as 1 degree pitch.
It is worth noting however that the size of the water beads that will retain (‘cling’) to the surface of the glass will increase exponentially to a reduction in pitch.
In this instance, the size of the internal framework is purely determined by the structural requirements of the design (imposed loads). Many different standard sections may be utilised and should the contract value and programme permit, a bespoke/unique extrusion can be developed. The quality of this system is very much down to the quality of installation and silicone sealing. Therefore, structural glazing should not be applied by unsuitably skilled operatives.
Unless a structurally glazed design requires additional specialist finishing’s/coatings, there are no additional programme considerations with the structural glazing system. Bespoke design programmes typically start at 10 weeks design and fabrication prior to site commencement (excluding approval periods).
Maintenance is often a poorly considered area, however represents a continuous cost consideration (cleaning, glass replacement etc.). It is important that all areas of maintenance are considered at length during the design process (a typical requirement under CDM regulations). Structural Glazing designs may contain large and heavy units, where expensive access and lifting equipment may be required during replacement/cleaning. In addition, structural glazing systems will often require access internally to cut away and remove the structural glazing tapes and adhesives. As an ongoing cost, glass maintenance considerations should be paramount and should be reviewed during the planning process. Structurally adhered systems and the adhesion should also be checked on an annual basic. When cleaning, structural glazing systems have the added advantage of a flush external glass finish, resulting in no obstructions or advanced cleaning considerations. When exploring the utilisation of any glazing system and/or design, it is also worth requesting a budget cost for glass replacement so that the risk of breakage and associated cost can be considered. Some companies may suggest that it is actually more cost effective to replace the glass and associated frame. In this instance the design is normally inappropriate and CDM regulations poorly considered.