Spider fittings and point-fixed glazing basics

Point-fixed (bolted) glazing hangs glass panels off stainless spider fittings rather than a continuous frame. It gives the maximum transparency for atria, entrances and feature facades.

The parts

• Spider — a stainless casting with two, three or four arms, fixed back to the structure (a fin, a mullion, a tension truss or a bracket).
• Routel (bolt fitting) — the bolt that passes through a drilled hole in the glass corner. Countersunk routels sit flush with the outer face; button routels stand proud. Articulated routels have a small ball joint to relieve bending at the hole.
• Glass — always toughened, and for overhead or high facades, heat-soaked toughened or laminated toughened to guard against spontaneous breakage and to keep the panel up if it cracks.

What decides the design

• Wind load on the facade sets the glass thickness and the fixing spacing — this is an engineered calculation, not a rule of thumb.
• The backing structure — fins, mullions or cables — has to be designed for the point loads and the deflection limits.
• Movement — articulated routels and slotted holes absorb thermal and structural movement so the glass is not stressed at the bolt.

Where we fit in

We supply the spiders, routels and glass connectors and can work to the facade engineer’s fixing layout. Point-fixed facades need an engineer’s design for the glass and the structure — bring the elevation, the wind zone and the support type and we will quote the fittings against the layout.