ISO 16293-1:2008

Overview

ISO 16293-1:2008 - "Glass in building - Basic soda lime silicate glass products - Part 1" defines and classifies basic soda‑lime silicate glass used in building. The standard sets out chemical composition ranges, general physical and mechanical properties, and broad quality criteria for clear and body‑tinted glass. It does not include specific dimensions, dimensional tolerances, detailed fault descriptions or product designation limits (these are to be addressed in future Part 2 for float glass). ISO 9050 (light transmittance measurement) is a normative reference for optical testing.

Key topics and requirements

• Scope and classification
  • Applies to basic soda‑lime silicate glass products commonly used in construction (including float glass definitions).
• Chemical composition
  • Typical mass fraction ranges: SiO2 69–74 %, Na2O 10–16 %, CaO 5–14 %, MgO 0–6 %, Al2O3 0–3 %, others 0–5 %.
• Physical and mechanical characteristics
  • Representative (conventional) values for normal annealed glass used for calculations where very high precision is not required:
    • Density ≈ 2 500 kg/m3
    • Mohs hardness ≈ 6
    • Young’s modulus ≈ 7 × 10^10 Pa
    • Poisson’s ratio ≈ 0.2
    • Specific heat ≈ 0.85 × 10^3 J/(kg·K) at 50 °C
    • Coefficient of linear expansion ≈ 9 × 10^-6 K^-1 (20–300 °C)
    • Thermal conductivity ≈ 1 W/(m·K)
    • Mean refractive index ≈ 1.5 (visible)
• Optical designation (clear glass)
  • Defines criteria for designating a product as clear transparent glass based on light transmittance measured per ISO 9050. Minimum transmittance values depend on nominal thickness (e.g., ~0.89 for 2 mm, decreasing to ~0.67 for 25 mm).
• Quality criteria
  • General guidance for evaluating optical quality (distortion, homogeneity), appearance (spot and linear faults) and stability of properties over time.

Applications and users

ISO 16293-1:2008 is practically useful for:

• Architects, façade and glazing engineers specifying glass performance and optical designation.
• Glass manufacturers and product developers establishing material composition and baseline physical properties.
• Building product certifiers, inspectors and specifiers assessing basic quality and optical criteria.
• Designers performing preliminary structural/thermal calculations where conventional glass property values are needed.

Keywords: ISO 16293-1:2008, soda‑lime silicate glass, glass in building, float glass, light transmittance, glass properties, clear glass designation.

Related standards

• ISO 9050 - Determination of light transmittance and related glazing factors (normative reference).
• ISO 16293-2 - Planned part addressing specific dimensions, tolerances and fault descriptions for float glass.