GRC — glass-reinforced concrete (written GFRC in North America) is a composite of fine cement mortar reinforced with alkali-resistant glass strands, cast or sprayed in molds to produce thin, strong, non-combustible (Class A1) architectural panels, cornices and profiles. For decades it has been the default way to put classical detail and cast-stone looks on buildings — which is exactly why anyone specifying facades should understand both its strengths and its logistics.
What is GRC made of?
A typical mix is white or grey cement, fine silica sand, water, polymers and 3–5% alkali-resistant glass fiber. The glass strands do the job steel rebar does in normal concrete — carry tension — but allow much thinner sections: panels are commonly 10–20 mm thick skins rather than solid castings. Every shape, however, requires a mold, and molds are exactly where GRC's cost and program behavior come from.
GRC properties at a glance
| Property | Value | Notes |
|---|---|---|
| Density | ~1,900–2,100 kg/m³ | industry range |
| Installed weight | ~35–55 kg/m² | vs 3–8 coated EPS, 80–95 stone |
| Reaction to fire | Non-combustible, Class A1 | its defining advantage |
| Thermal conductivity | ~0.5–1.0 W/m·K | not an insulator |
| Water absorption | ~5–15% by mass | moderate |
| Production | Mold-cast / sprayed | tooling cost · MOQ applies |
| Typical lead time | 6–12+ weeks | mold fabrication first |
| Fixing | Steel / aluminum sub-frame | crane for larger panels |
| Relative installed cost | ~0.7–0.9× | vs natural stone at 1.0× |
Where GRC is genuinely the right choice
Three situations keep GRC on specifications: briefs that mandate Class A1 non-combustible cladding; hard-use, ground-level public realm where abrasion and impact rule; and repeating panelized elevations where one mold amortizes over hundreds of identical casts. In those cases GRC has a long, credible track record.
Where GRC costs more than it looks
The weight cascades: a steel or aluminum sub-frame engineered per panel, crane time, more site trades and longer programs. The molds bind design: every new profile is tooling cost plus a minimum order, which penalizes villas and one-off elevations. And thermally it contributes nothing — insulation must be added behind it. On total installed cost GRC typically indexes at ~0.7–0.9× of natural stone; the detailed build-up is in the cost-drivers article.
GRC vs coated EPS
Where A1 is not mandated, coated EPS delivers the same profiles at 3–8 kg/m², CNC-cut without molds, hand-installed in days, at ~0.3–0.5× installed cost — the trade being its combustible core (C-s2, d0 as a system). The full three-way comparison with natural stone is here, the data tables are on the specs page, and the side-by-side document is in Tools → Documents.