Porous glass-ceramic materials are widely used in the construction, reconstruction and repair of objects for various purposes. The article establishes the influence of Mg(OH)2 and together with Al2O3 in the composition of a charge of siliceous rocks and soda ash on the structure and properties of porous glass-ceramic materials. A joint mechanochemical activation of the components was carried out in a planetary ball mill, and then the resulting charge was fired at a maximum temperature of 825 °C. The influence of the type and quantity of additives on the structure and properties of porous glass ceramics was established by thermal analysis (TA), X-ray phase analysis (XRD), etc. From the charge with the addition of Mg(OH)2 in glass ceramics, instead of wollastonite, diopside is formed, and instead of devitrite, combeite is formed. The influence of the phase composition of the samples on their properties has been established. The developed porous glass ceramics has an apparent density of 135-235 kg/m3, bending and compressive strength up to 1.6 and 4.2 MPa, respectively, a thermal conductivity coefficient of 0.05-0.067 W/m∙°C, thermal resistance of 170 °C, maximum operating temperature up to 870 °C, high chemical resistance. The developed materials are superior in many respects to foam glass and other analogues and can be used in the insulation of industrial and civil facilities.