GRC cladding is a rainscreen facade built from glass fibre reinforced concrete panels, called GFRC in the United States. This page covers it as a system rather than as a material: how the panels are fixed, what sits behind them, and what a specifier has to resolve to make the build-up work.
The panel is the easy part. A GRC cladding failure is almost never the panel. It is the fixing, the movement allowance, the cavity, the weather barrier behind it, or the junction detail at a slab edge or window head. Specify the system, not the skin.
The build-up
GRC cladding is normally a rainscreen. The panel sheds the bulk of the water and is deliberately not the airtight line. Behind it sits a drained and ventilated cavity, then the weather barrier and insulation, then the backing wall. Where the building class requires them, cavity barriers close the cavity at compartment lines.
A ventilated facade build-up keeps the panel dry on both faces, which is what makes the long service life achievable. It also means the fire performance of the wall is a property of the whole assembly, including the cavity, not of the panel in isolation.
Fixing and substructure
Panels hang off a substructure, normally aluminium or galvanised steel rail, rather than bearing on the panel below. Panel fixing systems in common use are hook-on rail, undercut anchors, and for stud frame panels a combination of gravity anchors and flex anchors that carry the weight at one point and allow movement everywhere else.
Movement is the detail that most often gets missed. Moisture movement and thermal expansion both act on a GRC panel, so movement joints and the joint design have to be set early. Open joint and sealed joint approaches both work; they are different systems and cannot be mixed by accident.
Preliminary substructure loads can be estimated with the facade load calculator, but the final design is the facade engineer’s.
Panel size, geometry and finish
Panel size is set by handling, transport and crane rather than by the material. Larger panels mean fewer joints and faster installation but a heavier lift. The panel weight and crane calculator gives the trade-off for a given size and thickness.
Geometry is where GRC separates itself from its alternatives. Single curvature, double curvature, freeform and perforated panels are all mould problems rather than material problems, and ShapeShift makes its moulds and runs CNC formwork in-house at the Batam factory.
Finishes are acid-etched, sandblasted, polished, exposed aggregate and off-form, with integral colour and oxide pigments through the mix. Colour consistency across a large facade is managed by batching and by a signed-off mock-up, which should be in the programme from the start.
Fire pathway by market
Which test applies depends entirely on where the building is. Australia and New Zealand work to the NCC with AS 1530.1, AS 1530.3 and AS 5113. Europe uses EN 13501-1. The United States uses NFPA 285 under the IBC. The United Kingdom uses BS 8414 against BR 135. Results do not transfer between them.
Compare all nine regimes in the facade fire standards atlas, and see what ShapeShell holds on the fire test evidence page. The pathway for any building is set by its fire engineer and approving authority.
System at a glance
| Element | Typical position |
|---|---|
| Panel | ShapeShell-RC, 15 to 25 mm typical thickness |
| System type | Drained and ventilated rainscreen |
| Substructure | Aluminium or galvanised steel rail |
| Fixing | Hook-on rail, undercut anchor, or gravity and flex anchors on stud frame |
| Joints | Open or sealed, set by the joint design, with movement joints as designed |
| Cavity | Ventilated, with cavity barriers where the building class requires |
| Finishes | Acid-etched, sandblasted, polished, exposed aggregate, off-form, integral colour |
| Fire | Assessed on the complete wall system against the standard adopted where the project is |
For the material itself see glass fibre reinforced concrete and the ShapeShell-RC page. For how GRC compares with the alternatives on weight, fire, curvature, lead time and cost band, see cladding panels compared.
Terms explained
Short definitions of the terms on this page, in our facade materials encyclopedia.
Common questions
What is GRC cladding?
A rainscreen facade built from glass fibre reinforced concrete panels, hung off a substructure over a drained and ventilated cavity. The same material is called GFRC in the United States.
How is GRC cladding fixed?
Panels hang off an aluminium or galvanised steel substructure using hook-on rail, undercut anchors, or gravity and flex anchors on stud frame panels. Panels do not bear on the panel below.
Does GRC cladding need a cavity?
In a rainscreen build-up, yes. The cavity is drained and ventilated, which keeps the panel dry on both faces and is what makes the long service life achievable. Cavity barriers are added where the building class requires them.
What panel sizes are possible?
Size is limited by handling, transport and crane rather than by the material. Fewer, larger panels mean fewer joints but a heavier lift. Use the panel weight and crane calculator to see the trade-off.
Is GRC cladding fire compliant?
Compliance is a property of the complete wall system and of the standard adopted where the building is, not of the panel on its own. ShapeShell-RC holds an AS/NZS 1530.1 non-combustibility result from Ignis Labs. See the fire test evidence page for the full position.
How long does GRC cladding last?
ShapeShift offers up to a 50 year warranty. Service life in practice depends on the build-up, the joint design and maintenance as much as on the panel.
Reviewed by Richard Halvorsen, General Manager, ShapeShift Technologies.