Fibre Reinforced Facade Encyclopedia: Materials
Architectural composites are fibre reinforced materials engineered and moulded specifically for building envelopes, interiors and public art, rather than for the industrial or marine markets the same technologies came from. Three matrices cover almost all of the work: cement reinforced with alkali resistant glass, thermoset resin reinforced with E glass, and gypsum reinforced with glass fibre. What makes them architectural is that the mould face is the finished product, geometry is set by the design rather than by a catalogue, and every element carries a surface that will be looked at closely for fifty years.
In industrial composites the laminate is the product and the surface is incidental. In architectural composites it is the other way around. The specification is written around the face, and the laminate or the mix is designed to deliver it at the required weight, span and fire pathway.
At a glance
| Property | Typical value | Note |
|---|---|---|
| Cementitious: glass fibre reinforced concrete | 30 to 50 kg/m², 10 to 20 mm skin | AR glass in Portland cement; non-combustible where tested to AS 1530.1 |
| Polymer: fibre reinforced polymer | 5 to 32 kg/m², 3 to 8 mm single skin | E glass in thermoset resin; reaction-to-fire and full-scale test pathway |
| Gypsum: glass fibre reinforced gypsum | 10 to 25 kg/m², 3 to 6 mm shell | Alpha gypsum, interior only, painted on site |
| Reinforcement | AR glass in cement; E glass in resin; glass fibre in gypsum | The fibre is matched to the matrix and is never interchangeable |
| Exposure | GRC external; FRP external; GRG interior and dry only | |
| Finish source | Mould face for GRC and FRP; paint for GRG | Coatings and gel coats are specified, not assumed |
| Geometry | Single and double curvature in all three | Limited by mould, demoulding draft and handling |
| Structural role | None; all three are non-loadbearing claddings or linings | Designed to wind load, self weight and handling |
| Typical tooling lead time | 2 to 6 weeks for CNC-cut moulds | |
| Quality evidence | Batch MOR and LOP for GRC; ignition loss and cure for FRP | Plus mock-ups and factory production control |
What makes a composite architectural
The technology is shared with boat hulls, tanks and cladding for industrial plant. The discipline is not. An architectural element is made in small numbers, often as a unique piece, to a tolerance measured against the building grid rather than against a production jig, with a surface that has to match its neighbours in colour and texture and weather at the same rate for decades.
Three consequences follow. The mould is the largest cost and the schedule driver, so design decisions that change tooling are expensive and design decisions that reuse tooling are nearly free. The surface specification carries as much weight as the structural one. And because every element is effectively a prototype, the quality system has to prove that the delivered piece matches the tested sample, which is why batch testing, mock-ups and factory production control appear in composite specifications where a sheet product would only need a data sheet.
The three matrices
Glass fibre reinforced concrete (GRC, GFRC) places alkali resistant glass in a cement matrix and is sprayed or cast into thin panels. It is the only one of the three that can be classified non-combustible, it takes deep relief and sharp arrises, and it weathers like concrete because it is concrete.
Fibre reinforced polymer (FRP) places E glass in a cured thermoset resin. It is three to ten times lighter than GRC, spans much further because shape rather than thickness gives it stiffness, and handles double curvature and undercuts that cementitious material cannot. It is a polymer composite and cannot be non-combustible.
Glass fibre reinforced gypsum (GRG, GFRG) places glass fibre in alpha gypsum and is cast as a thin shell. It is an interior material, painted on site, and it produces seamless sculpted ceilings, domes and column casings that no sheet system can match. It does not go outside or into wet areas.
Choosing the matrix
- External wall on a Type A or Type B building, Deemed-to-Satisfy route required: GRC, where the specific product holds an AS 1530.1 result
- Weight limited structure, recladding, or elements lifted without heavy plant: FRP, at a fifth to a tenth of the weight
- Double curvature, undercuts, long unsupported spans or large single elements: FRP, with the compliance pathway identified at concept stage
- Deep relief, sharp arrises, masonry or stone-like surface, and the geometry is developable: GRC
- Interior sculpted ceilings, vaults, coves and column casings with a painted finish: GRG
- Very high repetition of a flat panel with a simple profile: neither; a sheet product will usually be cheaper
The comparison that decides most projects is FRP against GRC, and it is rarely won on material cost per square metre. It is won on the structure that either removes or requires, the number of panels the geometry produces, and the compliance pathway the building can support.
Fire, stated by matrix
The matrix decides the pathway and no amount of fibre changes it. A cementitious composite has no organic binder and can be tested as non-combustible: ShapeShell-RC holds an AS/NZS 1530.1 result of Not Deemed Combustible from Ignis Labs. A gypsum composite is inorganic and fire resistant by nature, but any classification belongs to the tested product. A polymer composite burns and is classified by reaction-to-fire tests and full-scale facade tests instead: ShapeShell-RT holds an AS 5637 Group 1 classification from AWTA Product Testing, an EN 13501-1 classification of B-s2, and a pass of the full-scale BS 8414 and AS 5113 test at BRE Global.
What to specify and what to ask for
- The matrix and the fibre by name, with the zirconia content for AR glass in cementitious work and the resin family for polymer work
- Minimum rather than nominal skin or laminate thickness, and the method of verification
- Batch testing: modulus of rupture and limit of proportionality for GRC to the GRCA specification; ignition loss, void content and cure for FRP
- Fire evidence naming the test standard, the report number, the testing body and the tested product, not the material family
- A visual mock-up approved before tooling starts, because the mould face is the finish and it cannot be corrected afterwards
- Shop drawings covering anchors, joints, movement and handling points, coordinated with the structural tolerance behind
Standards and references
- GRCA Specification for the Manufacture, Curing and Testing of GRC Products; BS EN 1169 and BS EN 1170 series
- ASTM C1355 (glass fibre reinforced gypsum composites); ASTM C1666 (alkali resistant glass fibre)
- ASTM D790, ISO 14125, ASTM D638, ISO 527, ASTM D2584 (composite laminate testing)
- AS 1530.1, AS 1530.3, AS 5637.1 and AS 5113; NCC 2022 Volume One C2D10 and C1V3 (check the edition adopted in your jurisdiction)
- EN 13501-1; ASTM E84, ASTM E136 and NFPA 285
- AS/NZS 1170.2 (wind actions) and AS 4284 (building facade testing)
Related terms
Questions specifiers ask
What are architectural composites?
Fibre reinforced materials made specifically for buildings: glass fibre reinforced concrete, fibre reinforced polymer and glass fibre reinforced gypsum. They differ from industrial composites in that the moulded surface is the finished product and the tolerances are set by the building rather than by a production line.
Which architectural composite is non-combustible?
Only the cementitious one, and only where the specific product is tested. ShapeShell-RC holds an AS/NZS 1530.1 result of Not Deemed Combustible from Ignis Labs. Polymer composites cannot pass a combustibility test at all.
Can the same fibre be used in all three?
No. Cement requires alkali resistant glass with 16 percent or more zirconia because the cement pore solution attacks ordinary glass. Polymer laminates use E glass, which has no resistance to cement alkali. Mixing them up is a common and consequential specification error.
Why is tooling such a large part of the cost?
Every moulded composite element is made in a mould that has to be designed, built and finished to the same quality as the panel face. On low repetition work the mould can exceed the cost of the panels it produces, which is why repeated geometry is far cheaper than unique geometry at the same area.
Are architectural composites structural?
No. All three are non-loadbearing. They are designed for wind load, self weight, and the handling and demoulding stresses of manufacture, and they are supported by a separate structure or frame.
How long do they last?
Glass fibre reinforced concrete is designed for a 40 to 50 year service life. Fibre reinforced polymer with a gel coat or PVDF surface system reaches 50 years or more. Interior gypsum composites last as long as the interior they are part of.
Deciding between a cementitious and a polymer composite for a facade? ShapeShift produces GRC, FRP and GRG systems from one factory, so the comparison can be made on weight, geometry and fire pathway rather than on what one process can deliver. Compare the ShapeShell systems
Reviewed by Richard Halvorsen, General Manager, ShapeShift Technologies. Last updated September 2026.