The article presents a new methodology for the complex assessment of factors that restrict working conditions, which is based on matrix mechanisms of complex assessment, allowing to take into account heterogeneous complexity factors. As criteria for determining the cramped working conditions, the following are used: the mass and dimensions of the inventory, their number and the complexity of work to prepare the workplace for construction and installation work. The presented approach is able to take into account any factors‘ combination, which makes it possible to abandon the existing fixed number of coefficients. Illustrated examples are shown and that clearly demonstrates the methodology for assessing the complexity of construction and installation work. The proposed method can be used in the management of construction projects, to adjust the cost of work, etc. The screen forms of the software module created specifically to provide a comprehensive assessment of complexity factors are demonstrated.