The latest data extracted from the list of 647 manufacturers of windows and doors, 32 companies involved in the installation of assemblies and 113 glazing producers (the project was carried out by the specialized department of the Fereastra magazine) have made possible the development of a complex analysis - TOP 500 thermal insulating joinery manufacturers and TOP 100 insulating glass manufacturers - in which the turnovers reflect accurately the actual sales of joinery assemblies or thermal insulating glass. Thus, for the first time in comparison with the previous editions, the research shows more accurately the manner in which the main 500 companies, engaged in the production and installation of windows, doors and / or curtain walls, were influenced by the economic conditions specific to the recession period. Although in the last five years there have been significant changes in the market structure, the companies from the top - which outline basically the evolution of the windows segment - were characterized by stability and have tried to avoid the adverse effects of the economic crisis. If the structure of the top 500 thermal insulating joinery manufacturers is analysed by taking into account the year in which the companies were formed, it may be noted that a performance pole is attributed primarily to experienced companies which are clearly advantaged in terms of business stability. Thus, about 11% of last year’s window sales accomplished by companies in the industry represents the share of firms established in 1994 (representing 14% of the total of 500 companies). Nonetheless, the latter sum up together 14% of the total number of employees. Thus, the fact that only traditional companies have managed to occupy a place in the top 500 represents a certainty, especially because during the period 2008-2013 only 30 new significant businesses, which have as a primary activity the execution of thermal insulating joinery, were set up (all of them are included in the statistics).