In addition, by heating the hydrated glass powders at 350 °C we can obtain the inorganic foam board. The experimental results show that the density of the foam is about 0.16 ± 0.01 g/cm3, and the thermal conductivity is about 0.051 ± 0.001 W/m·K. It does not emit any dense smoke or expel toxic vapors when subjected to flame tests and has an excellent durability after a multi-day durability test. In conclusion, the hydrated glass may have broad application prospects in the lightweight thermal insulation material field.