Fibre Reinforced Facade Encyclopedia: Properties
Facade dead load is the permanent self weight of the external wall system, expressed in kilograms per square metre of facade area or as a pressure in kilopascals. It is not the weight of the panel alone. It is the panel plus its fixings, the rails and brackets, the insulation, the membrane and the flashings and cappings, and that total is what the structural engineer builds into the frame. Of all the facade numbers, it is the one that has to be right earliest, because it is locked into column and slab design long before a panel supplier is appointed.
A GRC rainscreen at 45 kg/m² including substructure, on a building with a 3.6 metre floor-to-floor height, applies about 1.6 kN per metre run along the slab edge. A 150 mm precast facade applies about 13 kN per metre run.
At a glance
| Property | Typical value | Note |
|---|---|---|
| FRP panel | 5 to 32 kg/m² | ShapeShell-RT published range; lighter flat, heavier for deep sections |
| GRC panel | 30 to 50 kg/m² | ShapeShell-RC published range; 10 to 20 mm skin with ribs or a stud frame |
| GRG panel (interior) | about 23 kg/m² | ShapeShell-RG, cast as a 3 to 6 mm alpha gypsum shell |
| Fibre cement 8 to 12 mm | 12 to 20 kg/m² | Typical rainscreen sheet |
| Aluminium composite panel 4 mm | 5 to 8 kg/m² | Panel only, cassette folded |
| Terracotta rainscreen 25 to 30 mm | 40 to 55 kg/m² | Typical extruded tile or baguette |
| Natural stone 30 mm granite | about 80 kg/m² | Rises steeply with thickness |
| Precast concrete 150 mm | about 360 kg/m² | For comparison; roughly eight times a GRC rainscreen |
| Aluminium substructure allowance | 6 to 12 kg/m² | Rails, brackets, thermal break pads and fixings |
| Steel substructure allowance | 10 to 35 kg/m² | Galvanised top hats low, heavy SHS grids high |
| Insulation and membrane | 3 to 10 kg/m² | 100 to 150 mm mineral wool plus sarking |
What the number has to include
An allowance that counts only the panel will be wrong by roughly half again for a light system. The complete figure is the panel, the anchors in it, the rails, the brackets and their thermal break pads, the insulation, the membrane, and the flashings, sills and cappings around every opening and edge.
It also has to include the heavy zones, not just the typical bay. Parapet cappings, deep reveals, sunshades, blades and any feature panel thicker than standard sit on the same slab edge as the light panels. An elevation averaging 45 kg per square metre can include a parapet run at 120 and blades at 200, concentrated where the structure is least generous.
Express it two ways: as a uniform pressure on facade area in kPa, which is how an allowance is written into a structural design brief, and as a line load on the slab edge in kN per metre run, which is what the edge beam is designed for. Converting needs the floor-to-floor height: 45 kg per square metre is about 0.44 kPa, and over 3.6 metres that is about 1.6 kN per metre of slab edge.
Weight by material, including substructure
The figures below are typical ranges for a complete rainscreen build-up, panel plus substructure plus insulation and membrane, in kilograms per square metre of facade area. A deeply moulded panel can sit well above the flat panel range, so confirm against supplier data for the actual geometry.
- FRP panel system: 15 to 45 kg/m² (panel 5 to 32, substructure 6 to 12, insulation and membrane 3 to 10)
- GRC panel system, skin with integral ribs: 40 to 70 kg/m² (panel 30 to 50)
- GRC panel system on a steel stud frame: 60 to 100 kg/m²
- Fibre cement rainscreen: 22 to 40 kg/m²
- Aluminium composite panel rainscreen: 15 to 28 kg/m²
- Solid aluminium sheet 3 mm, cassette: 20 to 32 kg/m²
- Zinc or copper sheet on a supporting deck: 25 to 40 kg/m²
- Terracotta rainscreen: 55 to 80 kg/m²
- UHPC panel 20 to 30 mm: 65 to 100 kg/m²
- Natural stone 30 mm on a rail system: 95 to 120 kg/m²
- Unitised double glazed curtain wall: 50 to 80 kg/m²
- Precast concrete 150 mm: 370 to 400 kg/m²
Ignoring precast, the spread between the lightest and heaviest options above is about twenty to one, a range of structural outcome from a decision often made on appearance.
The substructure allowance is not a rounding error
For a light panel, the substructure can weigh as much as the panel. An FRP panel at 10 kg per square metre on an aluminium rail and bracket system at 8 to 12 has almost doubled before the insulation is counted. It is also the easiest part to forget, because the panel weight is published while the substructure weight is a design output that does not exist yet when the allowance is needed.
Substructure weight is driven by span and wind pressure, not by the panel. Long rail spans save brackets and cost rail section, and a high corner-zone pressure adds section and fixings in zones that are already busy. Where the substructure is steel rather than aluminium, expect the allowance to roughly double. Carrying it in the structural brief as a separate line makes the source of any later overrun visible.
Why the structural engineer needs this first
The primary frame is designed on a facade allowance. That allowance sets edge beam depth, slab edge reinforcement, column loads down the building, transfer structure sizing, foundation loads and, on a tall building, part of the lateral system. All of it is fixed early, and by the time a facade subcontractor is appointed the drawings are issued and the lower floors are often poured.
The consequence of getting it wrong is asymmetric. A generous allowance costs a little extra structure. A tight allowance, followed by the discovery that the chosen facade is heavier, means strengthening work, a late change to a lighter system, or both. Recladding is sharper still: an existing frame has whatever capacity it has, the original facade weight is often unknown, and lightweight systems are frequently the only option that avoids strengthening.
Eccentricity is the part most often missed. A facade hung 200 to 400 mm outboard of the slab edge applies a torsion to the edge beam as well as a vertical load, and on a slender edge beam the torsion can govern. Give the structural engineer the load, the lever arm and the bracket spacing, not just a kilogram figure.
- Issue a facade weight allowance in kPa and kN per metre run at concept stage
- State the substructure allowance separately from the panel allowance
- Include parapets, blades, sunshades and feature zones, not just the typical bay
- Give the eccentricity from the slab edge and the bracket spacing
- Reconcile the allowance against shop drawing weights before release for manufacture
Where weight decides the outcome
Weight is why lightweight composites exist as facade materials. A GRC or FRP panel does the visual and weathering job of precast or stone at a fraction of the load, which brings a smaller frame, smaller foundations, lower seismic mass, smaller brackets and fewer thermal bridges, lighter craneage, and more panels per truck and per lift.
Craneage follows from panel weight and size, not from weight per square metre. A 3 by 1.5 metre GRC panel at 45 kg per square metre is about 200 kg and can be placed by a monorail or mast climber crew; in 30 mm stone it is close to 450 kg and needs mechanical handling; in 150 mm precast it is over 1.6 tonnes and needs a tower crane with the radius to reach it. That propagates into the programme, the access strategy and the cost of every lift.
Weight carries a carbon story too, though not a simple one. A lighter facade reduces the structure supporting it, usually the larger share of embodied carbon, but the panel material may be more carbon intensive per kilogram. Compare the wall assembly plus its share of structure, using an environmental product declaration rather than a generic material figure.
Standards and references
- AS/NZS 1170.1 Structural design actions, Part 1: Permanent, imposed and other actions
- AS/NZS 1170.0 Structural design actions, Part 0: General principles and load combinations
- AS 3600 Concrete structures and AS 4100 Steel structures, for the supporting frame
- GRCA Specification for the Manufacture, Curing and Testing of GRC Products
- EN 1991-1-1 Eurocode 1: Actions on structures, densities and self weight
- ASCE/SEI 7 Chapter 3, dead loads (US)
- EN 15804 and ISO 14025 for environmental product declarations used in weight and carbon comparisons
Related terms
Questions specifiers ask
How much does GRC cladding weigh per square metre?
A GRC facade panel is typically 30 to 50 kg per square metre including integral ribs or a stud frame. With substructure, insulation and membrane the complete rainscreen build-up is usually 40 to 70 kg per square metre.
How much lighter is GRC than precast concrete?
Roughly eight times. A 150 mm precast panel is about 360 kg per square metre against about 45 for a GRC rainscreen panel, which is why GRC is the common choice where an existing structure cannot take precast.
What weight allowance should be carried at concept stage?
State it in kPa on facade area and in kN per metre run at the slab edge, split between panel and substructure, including parapets, blades and feature zones. The structural engineer needs it before the frame is designed.
Does the substructure need to be counted separately?
Yes. For a light panel the substructure can weigh as much as the panel: 6 to 12 kg per square metre for aluminium rails and brackets, 10 to 35 for steel. It is the part most often omitted, because it does not exist yet when the allowance is set.
Why does facade eccentricity matter as much as weight?
Because the load is applied 200 to 400 mm outboard of the slab edge, which applies a torsion to the edge beam as well as a vertical load. Give the structural engineer the lever arm and the bracket spacing, not just a weight.
What is the lightest facade panel option?
FRP is the lightest architectural panel in common use, published at 5 to 32 kg per square metre for ShapeShell-RT depending on geometry. FRP is a polymer composite, classified by reaction-to-fire and full-scale facade testing rather than by non-combustibility.
Weight limited by an existing frame or a long span? ShapeShell-RT runs from 5 to 32 kg per square metre and ShapeShell-RC from 30 to 50, both with engineered fixing systems. Compare panel weights
Reviewed by Richard Halvorsen, General Manager, ShapeShift Technologies. Last updated September 2026.