Mizarstvo Košak d.o.o. was the first company in Slovenia to successfully obtain a certificate for wooden fire-proof windows (2017). Our fireproof windows have fire resistance of 60 minutes no. 1404-CPR-2863.

All details of the certificate obtained can be read on the website of the Slovenian National Building and Civil Engineering Institute: Inštitut za gradbeništvo ZAG Ljubljana.

The certificate applies to the following profiles:  profiles.


GLASS: Two-layer fire-proof glass EI60. By choosing glass, we have to decide for the most appropriate acoustic and thermal transmittance.
FRAMEWORK: It enables one-hand opening along the horizontal and vertical axis. We use the framework of a renowned German manufacturer.
WOOD: Three-layer laminated oak of the highest quality, without visible length joints of 95 mm thick, is used.
SURFACE TREATMENT: For surface treatment, we use the Remmers system, which, due to the four times application, provides the greatest protection against external factors. The customer can choose the colour according to our samples or the RAL colour scale.
SEAL: High quality plastic seals are installed in the windows. The characteristic of such seals is to remain flexible for a longer period of time than seals made on the basis of rubber.
GLASS BAR: The main task of the glass bar is the mechanical clamping of glass. The shape of the bars is selected by the customer and thus affects the appearance of the window.
1,1 W/m2K Ug
1,1 W/m2K Uf
1,4 W/m2K Uw
95 mm Thickness

Photo gallery from the fire- proof testing





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