Cable Net & Tensile Façade Systems

A cable-net façade supports glass not on a frame of mullions and transoms, nor on rigid fins, but on a grid of pre-tensioned steel cables stretched taut between the building structure. The cables — typically high-strength stainless rods or strand — are stressed in two directions to form a net; the glass is clamped at the crossing points; and the whole wall behaves like a tennis racket’s strings: flexible, pre-stressed, and stiffened by tension rather than by bending.

The most transparent wall there is

By replacing solid framing with thin cables, the cable net achieves the most diaphanous glazed wall in architecture — vast, uninterrupted planes of glass held by a structure so slender it almost disappears. It is the technology of grand entrance walls, atria, hotel and bank lobbies, transport halls and any space where the brief is a seemingly structureless wall of glass. Tensile façades are closely related: they extend the same pre-stressed, tension-only logic to cable trusses, bowstring structures and, with membranes, to fabric-and-cable envelopes.

The cable-net wall grew out of two engineering traditions: the pre-stressed cable structures pioneered for roofs (Frei Otto, the tension-structure engineers of the 1960s–70s) and the suspended-glass and point-fixed walls developed by Pilkington and by RFR with Peter Rice in the 1980s. Bringing tension structures into the vertical glazed plane produced the cable-net façade as a distinct type in the 1990s.

Defining early examples — the great glazed walls of corporate and cultural buildings in Germany and North America, and the cable-supported entrances of major commercial towers — established the language: a stiff perimeter structure, a pre-tensioned cable grid, point-clamped glass, and very large permitted deflections recovered elastically. Specialist structural engineers — schlaich bergermann partner, Dewhurst Macfarlane, RFR, Eckersley O’Callaghan — made the type a refined engineering discipline.

The cable net is a pre-stressed, tension-only structure, and understanding it means abandoning the intuition that a wall should be rigid. A cable can only pull, not push or bend, so the net is given its stiffness by pre-tension — it is stretched tight before any load is applied.

Stiffness from tension, not bending

When wind pushes on the glass, the net bows inward (or outward under suction). As it bows into a deeper curve, the cable tension rises, and that rising tension resists further movement — the structure is geometrically self-stiffening. There is no bending resistance to speak of, so the only way the net carries load is by deflecting until the increased tension balances the wind. When the wind drops, the elastic cables spring back. Deflections are large by curtain-wall standards — of the order of span/50 (one-fiftieth of the wall height), against span/175 to span/200 for a framed curtain wall — and this is by design, not a defect.

The consequences of big movement

Everything else in the wall must accommodate this large movement: the glass clamps must rotate, the glass joints must open and close, and the perimeter must take very high, fluctuating cable forces. The pre-tension force is itself substantial — often hundreds of kilonewtons per cable — because it must keep the net taut under the worst suction. Designing the net is a non-linear, large-displacement structural problem solved by form-finding and iterative analysis.

A cable net is an assembly of high-strength tension components, precision fittings and articulated glass connections, almost all in stainless steel for strength, corrosion resistance and appearance.

Cables and rods

The tension members are either spiral-strand or locked-coil stainless steel cable, or solid stainless tension rods, sized for the pre-tension plus wind force with a generous factor against the fluctuating, fatigue-prone loading. Stainless grades 1.4401/316 and duplex grades are used for corrosion resistance and strength; the cables are supplied with swaged or threaded end fittings.

End fittings, turnbuckles and tensioning

Each cable terminates in an adjustable end fitting — fork, eye or threaded terminal with a turnbuckle or tensioning nut — anchored into the perimeter structure. Tensioning is a controlled, sequenced operation, often monitored with load cells, because the net only behaves as designed once every cable carries its specified pre-load. Re-tensioning may be needed after the structure settles.

Glass clamps and patch fittings

At each cable crossing, an articulated clamp plate or patch fitting holds the corners of the four adjacent glass panes and connects them to the net. The fitting must rotate (articulate) as the net bows, so that the wall’s large deflection is not forced as bending into the brittle glass at the connection — the same articulation principle as point-fixed glazing. The glass is toughened laminated for strength and safe retention.

A cable net is only as good as the structure it pulls against. The very high cable pre-tension and wind forces must be anchored into a stiff perimeter, and resolving these forces is often the dominant structural challenge of the whole wall.

Anchoring the tension

The perimeter — edge beams, the primary building frame, or a dedicated stiff border structure — must resist the sum of all cable tensions without excessive deflection, because any give in the perimeter slackens the net. For tall walls this can mean substantial edge beams, tie-backs to the floors, or a stiff portal frame around the glazed opening. The interaction between the flexible net and the (relatively) stiff perimeter is central to the design.

Spanning long heights

For very tall walls, the simple two-way net is supplemented or replaced by cable trusses and bowstring trusses — pre-tensioned cable assemblies stiffened with spreaders that span the full height with minimal visible structure. These tensile sub-structures carry the wind to the floors while keeping the visible structure to a few slender cables and struts, and are a hallmark of the largest glazed halls and atria.

Glass on a cable net lives in a demanding environment: large deflections, point clamping, and exposure at the most prominent walls of a building. The selection rules mirror point-fixed glazing, with extra emphasis on movement.

Toughened laminated, articulated

Panes are toughened (for strength and clamp-load capacity) and laminated (so a broken pane is retained on its fittings and does not fall), typically with stiff ionoplast interlayers so the laminate keeps residual stiffness after breakage. Heat-soaking (EN 14179) is used to remove nickel-sulphide-prone panes, since a spontaneous fracture at height on a prestige wall is doubly serious. The clamp or patch connection is articulated so the wall’s large bow is absorbed as rotation, not as bending at the glass.

Joints and weather

Because the net moves so much, the silicone joints between panes must accommodate large, repeated movement, and the joint design and silicone selection are critical. Cable-net walls are commonly single-glazed (transparency over insulation) and so offer limited thermal and acoustic performance; insulated cable-net walls exist but the moving joints and clamped IGUs make high performance hard to achieve. Like point-fixing, the cable net is chosen for transparency, with environmental performance a secondary, carefully managed consideration.

Cable-net and tensile façades are pure structural-engineering territory, designed by specialist tension-structure and façade engineers using non-linear, large-displacement analysis that ordinary curtain-wall design never requires.

Form-finding and non-linear analysis

The geometry under pre-tension (the equilibrium shape of the stressed net) is established by form-finding, and the response to wind is solved by geometrically non-linear analysis that captures the tension-stiffening behaviour and the large displacements. Cable forces, perimeter reactions, glass clamp rotations and joint movements are all outputs of this analysis across the full range of pressure and suction. Dynamic and fatigue effects from fluctuating wind are checked because the cables are highly stressed tension members.

Robustness and testing

Robustness — the consequence of losing a cable, a clamp or a pane — is checked explicitly, since the structure is highly tensioned. Projects are proven by performance mock-ups tested for weather and for the large design movements, and often by load testing of the clamp-and-glass assembly. Glass design follows EN 16612 and structural-glass guidance; cable design follows EN 1993-1-11 (tension components).

The cable net trades performance for transparency, and every aspect of its behaviour is dominated by its large, deliberate movement.

Weather and movement

With no frame, the silicone joints between panes are the weather line, and they must remain weathertight while opening and closing through the net’s large deflections — the hardest single requirement of the system. Joint width, silicone movement capability and workmanship are critical, and the wall is tested at its full design movement.

Thermal and acoustic

Single-glazed cable nets give little thermal or acoustic performance and are used for unheated halls, buffer spaces and grand entrances where transparency is the point. Where insulation matters, the wall is either reconsidered (a framed system may be more appropriate) or designed as an insulated cable-supported wall with the attendant difficulty of moving, clamped IGUs. The environmental limitations are an accepted trade-off for the architecture.

Installing a cable net is a precise, sequenced structural operation quite unlike erecting a framed wall.

Sequence

The stiff perimeter structure is built and surveyed first. The cables are then installed and tensioned in a carefully controlled sequence — because tensioning one cable changes the forces in its neighbours, the order and the staged loads are engineered and monitored, often with load cells, until every cable reaches its design pre-tension and the net takes up its form-found shape. Only then are the glass panes installed and clamped at the nodes, and the silicone joints applied under controlled conditions. The work is slow, specialised and unforgiving, carried out by experienced tension-structure installers.

Tolerance and adjustment

The adjustable end fittings absorb tolerance and allow re-tensioning after initial settlement. Because the net is so sensitive to perimeter stiffness and pre-load, as-built survey and reconciliation against the analysis model are essential before the glass is fixed.

Cable-net and tensile façades are reserved for the grandest transparent spaces, where a near-structureless wall of glass is the architectural ambition and the budget and engineering effort can support it.

Their natural homes are large entrance and lobby walls of corporate and bank headquarters, hotel and atrium walls, museum and gallery halls, transport terminals and concourses, conservatories and winter gardens, and feature walls in flagship retail. They are not used for repetitive floors or where insulation and weather performance are paramount — there a framed curtain wall is the right choice. The cable net is a signature technology, deployed where its transparency creates a memorable space.

Cable-net and tensile façades are engineered, bespoke structures, so they rely on the structural, glass and façade frameworks together rather than a single product standard.

Applicable frameworks

Cable and tension-component design follows EN 1993-1-11 (steel tension components) with the relevant cable and fitting product standards; glass follows EN 12150 (toughened), EN 14179 (heat-soak), EN ISO 12543 (laminated) and EN 16612 (glass design), with the emerging structural-glass Eurocode (prEN 19100) and CEN/TC 250/SC11 guidance; wind loading follows EN 1991-1-4, often supplemented by wind-tunnel testing for large or exposed walls; and weather performance is verified by project mock-up testing to the EN 12152/12154/12179 family and the CWCT Standard at the full design movement. Certification is by engineered design and project-specific testing, not catalogue type-test.

A cable net is structurally one of the leanest glazed walls, using a tiny mass of highly stressed stainless steel to support a large area of glass — but, like point-fixed glazing, it is justified on architectural rather than energy grounds.

The minimal stainless structure is durable and recyclable, and the high-strength cables and fittings have a long service life. The thick toughened-laminated glass carries significant embodied energy, and single glazing offers no operational-energy benefit, so the wall should be sized to the architectural need rather than maximised. Stainless components are demountable and recyclable; the structural-silicone joints are, as in all bonded glazing, the main obstacle to clean separation at end of life. The honest sustainability case is that a cable net delivers a unique architectural effect with very little structural material — best used deliberately and sparingly, not as a default envelope.

Cable-net and tensile façades are delivered by makers of structural cable and tension hardware together with specialist façade contractors and structural-glass engineers who design and install the complete tensioned system.

Cable, fitting & system suppliers

• Pfeifer Seil- und Hebetechnik Memmingen, Germany — structural cable systems
• Carl Stahl Architektur Süßen, Germany — cable nets & tension façade systems
• Jakob Rope Systems Trubschachen, Switzerland — stainless cable nets
• Tripyramid Structures Westford, MA, USA — tension fittings & hardware
• seele Gersthofen, Germany — cable & tensile glass façades
• Novum Structures Menomonee Falls, WI, USA — cable-supported glazing

Structural-glass & tension-structure engineers

The defining cable-net walls are engineered by specialist tension-structure and structural-glass practices — among them schlaich bergermann partner, RFR, Eckersley O’Callaghan, Dewhurst Macfarlane and Arup’s façade groups — who form-find the net, size the cables and perimeter, and design the articulated glass connections as a coordinated, project-specific system.