Abstract: A method for making a building product from products of firing a clay-containing material and products of processing a lime-releasing material. The method comprises firing at least a clay-containing material up to at least beginning of its sinter, obtaining a molding mix comprising lime and products of firing a clay-containing material, molding a body of building product from the mix, and treating the body in a humid medium or in a medium containing water vapor. The products of firing a clay-containing material include a mixture of first and second portions that have been heated to respective first and second temperatures that are different from one another, the two different temperatures being within the temperature range from a temperature of beginning of dehydration to at least a temperature of sinter of clay, so that the products of firing comprise both products of dehydration and products of amorphization of clay.