At the dawn of the Patent Glazing era, a consistent production of glass had evolved at a dependable width and glazing bar centres have historically remained at this width since (approximately 600mm centres or 2 foot).
Conveniently, a 600mm wide pane of glass or double glazed unit up to 3000mm long can usually be carried safely and practically by two or three site personnel under each man’s arm, and this rule of thumb for the optimum width remains today.
Wider centres than 600mm can be used on Patent Glazing, but consideration must be given to the logistics of high quality access, provision of lifting equipment and future repairs/replacement which could become extremely costly if craneage is the only solution after building handover has occured.
Under CDM the Designer has a responsibility to specify suitable products to enable a project to be executed safely. It is therefore important that the Patent Glazing Contractor is approached early on in the design stage to discuss the practicalities of using glazing panels with large widths.
Patent Glazing is capable of having glazing bars spaced up to 1000mm wide with a suitable glass product but this is generally restricted to glass lengths of up to 2000mm or a glass pane area of 2m². Pane sizes exceeding this criteria would normally require the use of an expensive contract lift to install the glass safely.
We do not recommend the use of 6.4mm laminated glass in sloping patent glazing at centres over 650mm, due to the risk of mechanical breakage occurring (self weight).
At very wide centres, we recommend using toughened glass with an optional factory fitted anti-shatter film or a special toughened laminated composition .