Fibre Reinforced Facade Encyclopedia: Materials
Lightweight cladding is any external wall system whose finished weight is under roughly 50 kg per square metre, a threshold below which the facade largely stops governing the design of the structure that carries it. The category is defined by dead load rather than by material, and it includes metal sheet and composite panel, fibre cement, glass fibre reinforced concrete (GRC, GFRC) at the upper end, and fibre reinforced polymer (FRP) at the lower end. It matters most on three project types: tall buildings, where facade mass accumulates over every floor; recladding, where the existing frame has a fixed capacity; and long span or cantilevered structures, where every kilogram on the edge is expensive.
A 150 mm precast concrete panel weighs about 360 kg per square metre. A glass fibre reinforced concrete panel doing the same job weighs 30 to 50, and an FRP panel weighs 5 to 32. On a 10,000 square metre elevation that difference is more than 3,000 tonnes of dead load.
At a glance
| Property | Typical value | Note |
|---|---|---|
| Fibre reinforced polymer panel | 5 to 32 kg/m² | Polymer matrix; Performance Solution with a full-scale AS 5113 test |
| Aluminium composite panel, A2 core | 7 to 8 kg/m² at 4 mm | Limited combustibility class where the panel is tested |
| Solid aluminium plate | 8 to 9 kg/m² at 3 mm | Non-combustible metal; higher cost per square metre |
| Fibre cement sheet | 12 to 20 kg/m² at 8 to 12 mm | Named in the NCC among materials usable where non-combustible is required |
| Metal faced sandwich panel | 12 to 25 kg/m² | Core material decides the fire result, not the skins |
| Glass fibre reinforced concrete | 30 to 50 kg/m² | Non-combustible where tested to AS 1530.1; upper end of lightweight |
| Terracotta rainscreen | 35 to 55 kg/m² | Fired clay; at or just above the lightweight threshold |
| Substructure allowance | 5 to 15 kg/m² on top of the panel | Rails, brackets, fixings and cavity barriers |
| Reference: precast concrete | about 360 kg/m² at 150 mm | Not lightweight; included for comparison |
| Reference: brick veneer | about 200 kg/m² | Not lightweight; included for comparison |
What the weight saving buys
Facade dead load runs down through the slab edge, the columns, the core and the footings, and it is carried for the life of the building. Reducing it from 360 to 40 kg per square metre reduces the design load on every one of those elements, which shows up as smaller slab edge beams, less reinforcement, smaller footings and, in seismic regions, a lower inertial mass at every level.
The savings that get noticed first, though, are in installation. A panel of 3 by 6 metres weighs about 6.5 tonnes in precast and around 800 kg in glass fibre reinforced concrete, which changes the crane from a heavy mobile to a tower crane hook that is already there, or removes the crane from the sequence entirely. Transport carries more square metres per load. Site access improves. On recladding work these are often not savings but the whole feasibility case: the existing structure may simply not accept a heavy replacement facade, and lightweight cladding is what makes the project possible.
Comparing the options
- Fire pathway first: fibre cement, solid metal and glass fibre reinforced concrete can take the Deemed-to-Satisfy non-combustible route where tested; FRP, organic cored composites and timber composites cannot, and need a Performance Solution with a full-scale AS 5113 test
- Span between supports: sheet products such as fibre cement and metal composites need close fixing centres; moulded GRC spans further through ribs or a stud frame; FRP spans furthest because shape provides the stiffness
- Geometry: flat and folded work suits metal and sheet; curvature, deep relief and undercuts suit moulded composites, where tooling rather than area sets the cost
- Cost band, qualitatively: fibre cement and metal composite sit in the low band on flat repetitive elevations; solid metal plate and GRC in the middle band, with GRC improving sharply as mould reuse rises; FRP in the upper band on small quantities, and competitive where the geometry is complex or the weight saving removes structure
- Typical use: fibre cement and composite panel on repetitive residential and commercial elevations; GRC on moulded facades and recladding where non-combustibility is required; FRP on sculptural forms, large single elements and weight-critical recladding
Two products at the same weight can still be very different on site. A metal composite is delivered as flat sheet and folded into cassettes; a moulded composite arrives as a finished three-dimensional element that needs a stillage, a lifting frame and a set-out. Compare delivered systems rather than panel weights alone.
What you trade away
Stiffness. Light panels almost always have a lower elastic modulus or a much thinner section, so deflection under wind rather than strength sets the panel size and the fixing centres.
Mass. Acoustic performance of a single leaf follows its mass, so a light facade needs the insulation, the cavity and the internal lining to do the acoustic work, and that has to be designed rather than assumed. Thermal mass disappears with it.
Self weight as ballast. Wind suction is usually the governing load case on a lightweight facade, because there is little panel weight resisting uplift. Fixings, brackets and the substructure are designed for suction from AS/NZS 1170.2, and corner and parapet zones carry the highest pressures.
Impact resistance. Thin skins are more vulnerable to impact, vandalism and back-of-house traffic at ground level, which is why lightweight systems are often paired with a more robust material through the first few metres.
Getting the dead load number right
A facade weight quoted by a supplier is usually the panel alone. The figure the structural engineer needs is the complete external wall: panel, substructure rails and brackets, insulation, sarking and membranes, cavity barriers, and the internal lining and framing where these are part of the facade contract. The substructure alone commonly adds 5 to 15 kg per square metre, and it can exceed the panel weight on a thin metal system.
Fire and the weight trade
The lightest options are the most likely to be combustible, because low density usually means an organic matrix or an organic core. That is the central tension in lightweight facade design and it should be resolved at concept stage, not at submission.
Under NCC 2022 Volume One (check the edition adopted in your jurisdiction), external walls of Type A and Type B buildings must be non-combustible on the Deemed-to-Satisfy route. Glass fibre reinforced concrete can meet that directly where tested: ShapeShell-RC holds an AS/NZS 1530.1 result of Not Deemed Combustible from Ignis Labs, at 30 to 50 kg per square metre. FRP is lighter again at 5 to 32 kg per square metre, but it is a polymer composite and is never non-combustible; it reaches the same wall through a Performance Solution supported by a full-scale test, and ShapeShell-RT passed the full-scale BS 8414 and AS 5113 test at BRE Global with an AS 5637 Group 1 classification from AWTA Product Testing. The weight difference between those two systems is real, and so is the difference in the approvals path.
Standards and references
- AS/NZS 1170.1 (permanent and imposed actions) and AS/NZS 1170.2 (wind actions)
- AS 1530.1 (combustibility) and AS 5113 (full-scale facade fire test)
- NCC 2022 Volume One C2D10, C1V3 and Specification 7
- AS 4284 (building facade testing) for serviceability and structural performance of the assembled system
- EN 13501-1 and BS 8414 with BR 135; ASTM E136 and NFPA 285
- GRCA Specification and BS EN 1170 series for glass fibre reinforced concrete weights and properties
Related terms
Questions specifiers ask
What counts as lightweight cladding?
As a working threshold, an external wall system under about 50 kg per square metre including its substructure. Below that the facade rarely governs the design of the structure carrying it; above it, the slab edges, columns and footings start responding to the facade weight.
What is the lightest facade cladding?
Fibre reinforced polymer, at 5 to 32 kg per square metre, followed by thin metal composite panel at around 5 to 8. The lightest options are generally the most likely to be combustible, which is the trade-off to resolve first.
Does lightweight cladding save money?
It saves structure, crane time, transport and programme, and on recladding it is often what makes the project feasible at all. Whether it saves on the facade package itself depends on repetition and geometry, since moulded lightweight systems are priced by tooling rather than by area.
Is lightweight cladding less safe in a fire?
Weight and fire performance are unrelated properties. Glass fibre reinforced concrete is lightweight and can be classified non-combustible where tested. What matters is the test result for the specific product and the compliance pathway, not the kilograms.
What weight should be allowed in the structural design?
Use the complete external wall weight per square metre of elevation, including substructure, insulation, membranes and cavity barriers, not the panel weight from a supplier data sheet. Substructure alone typically adds 5 to 15 kg per square metre.
Why is wind suction the governing load?
Because a light panel has almost no self weight to resist uplift. Fixings, brackets and rails on a lightweight facade are designed for the suction pressures in AS/NZS 1170.2, which are highest at corners, parapets and roof edges.
Working the dead load numbers for a facade option study? ShapeShell-RT runs 5 to 32 kg per square metre and ShapeShell-RC 30 to 50, and our facade calculators will size the comparison. Open the facade calculators
Reviewed by Richard Halvorsen, General Manager, ShapeShift Technologies. Last updated September 2026.