Fibre Reinforced Facade Encyclopedia: Materials
GFRC versus precast is the choice between a thin glass fibre reinforced cement skin and a conventionally reinforced concrete panel. Both are cementitious, both are non-combustible when tested, and both are cast in a factory against a mould. They separate on thickness and what that thickness allows: glass fibre reinforced concrete (GRC in Australia and the UK, GFRC in North America) is a 10 to 20 mm skin that cannot carry building load, and precast is a 100 to 200 mm reinforced element that can.
A 15 mm GRC skin with ribs weighs 30 to 50 kg per square metre. The 150 mm precast panel doing the same cladding job weighs about 360 kg per square metre. GRC is roughly a fifth to an eighth of the weight.
At a glance
| Property | Typical value | Note |
|---|---|---|
| Thickness | GRC 10 to 20 mm skin; precast 100 to 200 mm | Precast thickness is set by cover, not strength |
| Weight | GRC 30 to 50 kg/m²; precast 240 to 480 kg/m² | At 150 mm precast is about 360 kg/m² |
| Weight ratio | GRC is about one fifth to one eighth | Compare system weight, not skin thickness |
| Reinforcement | GRC alkali resistant glass fibre; precast steel bar and mesh | No cover requirement in GRC |
| Load-bearing | GRC no; precast yes | Precast can be wall, shear core and cladding at once |
| Fire | Both non-combustible when tested | GRC to AS 1530.1; precast FRL from AS 3600 thickness and cover |
| Achievable geometry | GRC double curvature and deep relief; precast largely planar | GRC releases from lighter, cheaper moulds |
| Typical panel size | GRC about 3 by 6 m; precast up to about 3 by 12 m | Precast limited by transport and crane, not by material |
| Thermal mass and acoustics | Precast materially higher | About 2,200 kJ/m³·K; sound reduction follows mass |
| Cost at simple repeating geometry | Precast usually lower per m² | Local supply and a mature trade base |
Why the thickness differs
Precast concrete is reinforced with steel, and steel corrodes unless it is buried in enough alkaline concrete to stay passive. AS 3600 requires 25 to 50 mm of cover on both faces depending on exposure class, with bar between. That arithmetic puts the practical floor for a reinforced panel at about 100 mm and makes 125 to 150 mm the normal cladding thickness. It is a durability constraint, not a strength one.
GRC has no steel. The reinforcement is millions of short alkali resistant glass filaments distributed through the cement matrix, so there is nothing to corrode and no cover to provide. The skin can be as thin as spraying and handling allow, which is 10 to 20 mm, and stiffness is recovered from shape: integral ribs formed in the same pour, or a light galvanised steel stud frame with flex and gravity anchors connecting the skin to it. The result is the same cladding function at a fifth to an eighth of the mass.
Where precast wins
Structural capacity is the decisive one. A precast panel can be a load-bearing wall, a shear wall and the cladding at the same time. On a car park, warehouse or low-rise commercial building one element does three jobs, and the comparison with a thin skin is not meaningful, because GRC can only ever do the third. GRC is always an applied skin on someone else’s structure.
Cost at simple repetitive geometry is the second. Where the panels are flat or near flat and the same mould is used many times, precast is normally cheaper per square metre supplied and installed. The raw materials are inexpensive, the process is highly industrialised and the mould amortises quickly.
Local supply and trade depth are the third and are often underrated. Precast is made in every Australian capital and most regional centres, so transport distances are short, lead times are predictable and there is a deep pool of erectors who install it every week. GRC is made in fewer places and is more likely to be shipped.
Fourth, precast brings thermal mass and mass-law acoustic performance that a 15 mm skin cannot approach, and its fire resistance level comes free from its own thickness and cover under AS 3600 rather than needing a separate rated wall behind it. Fifth, its durability record is longer: 60 to 100 years against a GRC design life usually quoted at 40 to 50.
Where GRC wins
Weight, first and by a wide margin. Facade dead load of 30 to 50 kg per square metre instead of 240 to 480 changes the structure that carries it: a smaller slab edge, less perimeter reinforcement, smaller columns and a measurable reduction in foundation load. On site it means a smaller crane and more lifts per day. The saving sits upstream in the structure and downstream in erection, not in the facade package, which is why a comparison done on supplied panel rate alone misses it.
Recladding is where weight stops being an optimisation and becomes a gate. An existing building was designed for the facade it had, and adding 360 kg per square metre to a frame sized for a lightweight or rendered wall usually needs strengthening that costs more than the facade. A 30 to 50 kg per square metre GRC skin often does fit, which is the usual reason GRC is chosen on combustible cladding remediation.
Thin complex geometry is the third. A precast mould is heavy, costly and slow to change, and a 150 mm reinforced section cannot follow tight double curvature or deep undercuts without becoming too heavy to lift. A sprayed GRC skin follows the mould face at 15 mm, so curvature and relief cost tooling rather than tonnage. Where every unit on an elevation differs, GRC tooling is far cheaper to vary.
Fourth, GRC delivers the same architectural finishes as precast, off-form, acid etch, sandblast, exposed aggregate and integral colour, from a far lighter element, and it delivers non-combustibility on the same Deemed-to-Satisfy basis when tested to AS 1530.1.
What the two share
Both are cement composites cast against a mould, so both take their surface finish from the mould face and the mix rather than from a coating, and both carry the same colour consistency management across batches, the same efflorescence risk and the same repair approach. Both are non-combustible in the code sense when evidenced, GRC by an AS 1530.1 report and precast by the nature of concrete.
Both fix back to structure with gravity and restraint anchors, both need joints sized for movement and erection tolerance, and both are tested as assemblies under AS 4284 where the project scale warrants it.
Deciding
Ask first whether the panel is structure. If it is, the answer is precast or another structural system and GRC is not in the conversation. If it is cladding only, ask what dead load the structure will accept, because on recladding and weight-sensitive new build that answer alone selects GRC. If load is not binding, geometry decides: planar and repetitive favours precast on cost and local supply; curved, deeply modelled or non-repeating favours GRC on tooling and liftability.
Check lead time explicitly rather than assuming it. Precast is usually faster to procure locally; GRC lead time is dominated by mould manufacture, so a complex non-repeating facade should have its tooling programme confirmed before the panel type is locked. Where weight rules out even GRC, the next step down is a polymer composite at 5 to 32 kg per square metre, with the fire consequences that carries.
Standards and references
- GRCA Specification for the Manufacture, Curing and Testing of GRC Products; BS EN 1169 and BS EN 1170 parts 1 to 8
- PCI MNL-128 (GFRC panels) and PCI MNL-117 (architectural precast quality control)
- AS 3600 Concrete structures, including Section 5 fire resistance from thickness and cover
- AS 3610 Formwork for concrete (surface finish classes); AS 3850 Prefabricated concrete elements
- AS 1530.1 combustibility; NCC 2022 Volume One Specification 7 and C2D10 (check the edition adopted in your jurisdiction)
- AS/NZS 1170.2 wind actions; AS 4284 Testing of building facades
Related terms
Questions specifiers ask
How much lighter is GFRC than precast?
Roughly a fifth to an eighth. A GRC facade panel including ribs or a stud frame runs 30 to 50 kg per square metre, against about 240 kg for 100 mm precast, 360 kg for 150 mm and 480 kg for 200 mm.
Can GFRC replace precast concrete?
As cladding, often yes. As structure, no. GRC is a thin non load-bearing skin, so it can replace a precast cladding panel but cannot replace a load-bearing or shear wall panel.
Which is cheaper, GFRC or precast?
Precast is usually cheaper per square metre on simple repeating planar panels, and it has the advantage of local supply almost everywhere. GRC becomes competitive and then cheaper as geometry becomes complex and units stop repeating, and it can reduce structural and craneage cost that never appears in the facade rate.
Is GFRC as durable as precast?
Precast has the longer record, with design lives of 60 to 100 years against 40 to 50 commonly quoted for GRC. GRC does not corrode because it has no steel, which removes the main precast failure mode, but its design uses long-term aged strength values rather than 28-day values to account for change over time.
Why is precast so much thicker than GFRC?
Because steel reinforcement needs 25 to 50 mm of concrete cover on each face to stay protected from corrosion. GRC has no steel, so there is no cover requirement and the skin can be 10 to 20 mm.
Are both GFRC and precast non-combustible?
Both are cementitious with no polymer matrix. Precast concrete satisfies the requirement directly and derives its fire resistance level from thickness and cover under AS 3600. A GRC product needs its own AS 1530.1 report; ShapeShell-RC holds a Not Deemed Combustible result from Ignis Labs.
Recladding a building that cannot carry precast? ShapeShell-RC is our GRC system at 30 to 50 kg per square metre, Not Deemed Combustible to AS/NZS 1530.1 by Ignis Labs. See ShapeShell-RC specifications
Reviewed by Richard Halvorsen, General Manager, ShapeShift Technologies. Last updated September 2026.