# Structural Analysis of Factors Influencing the Costs of Facade System Implementation
## 1 Introduction  
External facades of buildings and other structures shape the image of every building, creating the architecture of cities. The dynamic development of technology, the discovery of new innovative building materials [1], as well as the ever-increasing technical, production, and execution capabilities have resulted in exterior walls with complex shapes and forms. Traditional concrete forms as a symbol of durability and stability have been replaced by lightweight enclosures--for example, in the form of aluminium-glass facades and ventilated facades [2]. Aluminium and glass facades are built from aluminium sections, and the spaces between the aluminium construction is filled with glass. Glass that is used in construction should meet the requirements of thermal protection, fire protection, burglary protection, protection against noise, and safety of use [3]. A solid building made in the form of aluminium-glass facades is an indispensable element of architecture for a modern city [4]. Also, ventilated facade systems have gained much attention. It is a cladding system, which incorporates the insulation layer, positioned usually on the external surface of the wall, the air cavity and the outer skin [5]. The air gap allows air to enter and flow through the facade. The external part of the ventilated facade is a panel suspended, glued, or screwed to the substructure. Ventilated facades allow for shaping external claddings from various materials, structures, textures, or colours. The panels can be made of many materials, including wood, fiber concrete, aluminium and ceramics. Due to their high aesthetics, ventilated facades are increasingly often used as external parts of newly built buildings,but they are also perfect for buildings undergoing renovations [2; 6]. This makes the ventilated facade an effective form of finishing the building--it adds prestige and distinguishes it from the environment. Descriptions and photos or characteristics of the discussed facade systems can be found in a number of publications [4; 7; 8]. The modern trend in the design of exterior facades as lightweight structures is primarily reflected in examples of public buildings, and constitutes the mainstay of urban architecture. The construction of skyscrapers and high-rise buildings are symbols of all larger metropolises. The external facades of such buildings are no longer just the outer cladding itself, but a combination of many interdisciplinary functions. They combine stability and reliability with aesthetics, usability [9], energy efficiency, and ecology [10]. All these aspects affect the quality of the assembly process, time of execution, and costs incurred [3]. These three elements determine the success of each construction project. Many studies presented in the literature concern the quality of construction projects [11], their costs [12; 13], and time schedule [14], as well as the maintenance of the existing buildings [15] and the opportunity to improve the energy efficiency of buildings [16]. Reliable cost estimation is one of the most important aspects of construction projects, both from the investor's and the contractor's point of view [17]. Estimating the costs of facade systems is time-consuming and complicated [3]. The calculation process is influenced by architectural, construction, and system data, as well as parameters related to production and the type of assembly. It is necessary to have an individual approach to each investment, starting from the analysis of design documentation and ending with the location of the construction project. The cost amount is influenced not only by the prices of individual facade elements, but additionally by the costs of their execution in the production plant and assembly on the construction site. In the case of facade system implementation, one should take into account indirect costs, widely understood, which are closely related to the specific location of the investment, the availability of land around the building, or the option of setting scaffolding or others factors [18].