Watch this flat roof insulation walkthrough to see how cellular glass board (140 kg/m³) is installed beneath waterproofing as a load-bearing thermal layer. We demonstrate high compressive strength under rooftop equipment and foot traffic, closed-cell waterproof performance after ponding, and Class A1 non-combustible fire protection. Learn why foam glass stays dimensionally stable, resists moisture, and supports a flat, dependable roof build-up. Practical tips and performance insights for B2B specifiers and contractors.