The adhesion of polyurethane thermal insulation to a waterproof outer casing of polyethylene in the construction of preinsulated bonded pipe systems used as a building material for directly buried hot water networks is investigated. In order to extend the life of pipes for hot water networks from standard 30 years to 50 years or more, it is proposed to use polyurea as a waterproof coating. It is proposed to determine the adhesion strength of thermal insulation with a waterproof outer casing for shear in the tangential direction at the edge "Waterproof outer casing of polyethylene - Polyurethane thermal insulation". Test results are presented. The results of calculations of the heat losses of the preinsulated pipe construction are presented. The testing results of the behaviour of polyurea coating in the ground are presented. Conclusions are drawn about the possibility of using polyurea as a waterproof coating for preinsulated bonded pipe systems for directly buried hot water networks.