Strength band
paper faces take bending; wet boards are scrap
Numbers below are bands used by working engineers, not live quotes. Tensile note: paper faces take bending; wet boards are scrap.
Fire performance in this atlas is editorial. Real projects need the assembly report.
Mechanical
Stiffness
Modulus follows chemistry and orientation — not the marketing nickname.
Toughness
Crack growth, not peak stress, retires most real parts.
Fatigue / creep
Cyclic and time-dependent damage dominate certificates issued on static coupons.
Hardness / hand
Indentation, drape or compressive class — whichever the trade actually measures.
Thermal
Conductivity
~0.17 W/m·K — Gypsum board is not a substitute for a dedicated λ layer.
Service temperature
Melting / softening / decomposition band: calcines ~80–180 °C (dehydration).
Expansion
Joints and clearances must follow the expansion class of Gypsum board, not of steel-by-habit.
Thermal mass
Density ~700–1000 kg/m³ sets how fast a section changes temperature.
Ageing of λ
Foams, VIPs and moist batts drift; quote aged values.
Electrical
Conductor or dielectric
Gypsum board is generally a dielectric or semiconductor film, not building wire.
Static / EMI
Fillers and moisture change resistivity more than brochures admit.
Standards language
IACS, volume resistivity or dielectric strength — pick the quantity the job uses.
Fire
Reaction to fire
Typical declared class: A2-s1,d0 typical; core A1. This is not a universal passport.
Resistance vs reaction
Euroclass is reaction. EI/R ratings are assemblies — boards, coats, cavities.
Melt-drip / char
Gypsum board tends to char or stay inorganic rather than melt-drip like commodity olefins.
Smoke / toxicity
CO, HCN, HF or fibres — the species depend on chemistry. Name the test (ISO 5659, EN 45545, NFPA 1971).
If a salesperson quotes a single “safety score”, ask which standard, which thickness, which year.
Keep exploring
More in Fire performance
👨🚒
Nomex
DuPont’s meta-aramid — fire-fighter turnout, electrical paper and a char that does not melt-drip like nylon.
Overall 65 🧯Intumescent coating
Paints that swell into insulating char — the thin-film way to give steel an R-rating without bulky boards.
Overall 58 🌡️Ceramic fibre
Spun refractory fibres for 1000–1400 °C — kiln linings, gaskets, and a respirable-fibre caution that AES grades try to ease.
Overall 62