As a result of the dynamic development of technology, glass-aluminum facades are now widely used. Not only representative facades in city centers, but also small buildings, such as commercial and office buildings, are equipped with aesthetic glass facades. To properly fulfill the functions of a curtain wall (thermal protection, water tightness, etc.), glassaluminum systems must be properly designed and assembled. The aim of the article is to identify the most common errors made when implementing small investments on the basis of information about problems that emerge during assembly, as well as the reasons for complaints filed by investors. The most popular post-and-beam systems on small construction sites were analyzed. The data was obtained from companies operating in the northern part of the Silesian Voivodeship, dealing with the distribution and assembly of these systems. Scoring was made of the negative impact of the identified errors on the structure. It was found that the main problem in this issue is the lack of due diligence during assembly, in particular deviations from catalog recommendations.