The paper deals with the automation of calculation of building structures, in particular, multilayered structures. When designing monolithic reinforced concrete slabs in fixed formwork, it is necessary to perform very complex calculations, with many parameters being calculated, and, accordingly, it is necessary to exclude calculation errors. The proposed solution is a software module, which, firstly, solves this problem, and secondly, has a unique opportunity to select the calculation mode, which takes into account the relevant functional problem. The system of functional calculation tasks of building constructions is formed. A description of the software module design is given. Automation of calculations of reinforced concrete structures due to the use of the program module provides reduction of time expenses of their performance, reduces labour and financial expenses, considerably raises the quality of calculations.