Reinforced plastics are widely used in various fields of technology for a wide variety of structures. They provide high strength at low density, resistance to aggressive media, low material intensity of production, high manufacturability, the ability to regulate heat and electrical conductivity over a wide range, the ability to repair without the use of special equipment, they perform in a broad range of temperatures and stresses. Reinforced polymer composites with the use of fiberglass-based textile materials as reinforcement are the most used due to their availability, low cost and high strength properties. This scientific paper presents the results of specimen tests with a substrate of various types of steel, adhesive compositions as bonding material, and fiberglass as reinforcing material. The influence of the properties of the substrate and coating materials, and the ratio of their thicknesses on the theoretical strength of the composite element was investigated. The results obtained will make it possible to clarify the design schemes and dependencies in the design and repair of structural elements with reinforced polymer coatings.