One of the most important ways in improving the research's efficiency is an experiment's planning. The aim of the study is to identify and study various factors that can affect the productivity of brick layers during bricklaying of townhouses in Iraq. Visual observation, timing and photographs of the working day were carried out during eight working weeks. In the process of daily monitoring, causal relationships of the formation of downtime and overtime work of bricklayers were identified. The most significant factors are untimely delivery of materials and alteration of performed work. The data obtained are the basis for the development of a mathematical model of labor productivity indicators. An analysis of the data on the functioning of the construction technological system for erecting brick walls of buildings shows that its states can be modeled by regular Markov processes. The data obtained are the basis for the development of a mathematical model of labor productivity indicators. © Published under licence by IOP Publishing Ltd.