The key technological task in the construction of underground buildings and structures is the development of a reliable waterproofing system. Currently, insufficient attention is paid to the issues of technological assurance of waterproofing reliability. This gives rise to a complex problem caused by accelerated deterioration of underground structures, deterioration of sanitary and other characteristics of underground exploited spaces. Complex and expensive restoration repairs need to be carried out, however their results are often unsatisfactory, as practice shows. The article reveals and analyzes technological vulnerabilities of the subsurface part of buildings and structures such as expansion and construction joints of cast-in-situ and prefabricated cast-in-situ structures as well as engineering communications input nodes in the subsurface part of a construction project. The main disadvantages of the existing structural and technological solutions to waterproof these elements have been identified, since they significantly reduce the technological reliability of the entire waterproofing system of the underground building or structure. Having employed industry inventive technologies, the authors suggested a few technical solutions allowing technological reliability of the revealed waterproofing system vulnerabilities to be enhanced. The novelty and practical applicability of the developed solutions are confirmed by patents. The developed solutions are planned to be implemented soon on an industrial scale at one of the enterprises of the Ural region, which expands its product range for reliable waterproofing of various buildings and structures.