The directions of energy and resource saving remain a priority in building science. This is especially concerns to the structural elements of mass production. These elements include large concrete blocks of basement walls (foundation blocks), theirs bearing capacity, even in high-rise building, is used only for 30–50 %. Therefore, starting with the widespread establishment in construction, various ways to improve their constructive forms were proposed to reduce their own weight and optimization. One of the most effective ways is cavity formation.