Transparent Facade Systems

Planar, or spider, glazing removes the visual line between inside and outside. Glass panels are not held in aluminium profiles. Articulated stainless steel rotules and spider arms fix each panel to the supporting structure at points.

There is no aluminium cover grid. Wind and suction loads pass from the glass holes, through the articulated rotules, into the main structure. The joints between the panes are sealed with UV-resistant neutral silicone gaskets.

Types of Supporting Structure

A steel structure uses circular hollow sections, box sections or space-frame beams sized for the design. Spider brackets are welded to the steel or bolted with adjustable clamp flanges. This suits wide spans and plaza entrances and showrooms under high wind load.

Where the aim is the lightest possible structure, the vertical fins are laminated tempered glass, for example 12+12 mm or 15+15 mm. Facade panes are fixed to those glass fins with double-sided spiders, so almost no metal is visible.

A tension system uses prestressed stainless steel cable nets or tie rods, vertical and horizontal, to get stiffness from very little mass. The cables are tensioned with a torque wrench to control wind deflection. This is used on contemporary airport terminals and atriums.

Point Fixings and Safety

Spider arms are cast in AISI 316 stainless steel (CF8M) so they resist weather, moisture and corrosion. One-, two-, three- and four-arm articulated fittings are used.

Articulated spherical rotules take up glass deflection, thermal movement and seismic displacement. The bolt head can be countersunk or a button head. High-strength EPDM and aluminium washers keep the glass off the metal.

The glass is always toughened and laminated, for example 8+8 mm or 10+10 mm with PVB or a SentryGlas ionoplast interlayer, so a broken pane stays in place. Where thermal insulation is required, point-fixed double glazing with sealed washers is used.